Cooling System

Last updated: March 23, 2003

Radiator Cap

Date: Tue, 21 Sep 1999 15:20:25 -0700
From: "Ulen, Robert S" (

The early 93's came with 1.3 bar caps. Then Mazda had a recall on the cooling system because it was suspected of leaking coolant and starting engine bay fires. The recall had some cooling system components replaced to withstand more heat, plus the pressure cap was changed to a 0.9 bar cap.

I have also seen FDs with 1.1 bar caps, so don't know when these where used - maybe between the original 1.3 and the 0.9 recall caps.

Anyway, I believe that 1.3 bar is too much pressure for the FDs cooling system, and if anyone is using one, they should replace it. It may also mean that the cooling system recall has not been done on the car yet. If you suspect the recall has not been done, call Mazda Customer Service at 1-800-222-5500 and give them the VIN of the car. They can tell you if and when the recall(s) where done.

The only draw back of the lower pressure cap is that if you run the car hard, it may want to boil over. You should use at least 40 % ethylene glycol (antifreeze) with distilled water and a bottle of Redline water-wetter to ensure good cooling system performance. If your antifreeze ratio is too low, you are also decreasing the boiling temperature of the coolant, but getting slightly better heat transfer to the coolant.


Date: Thu, 20 Nov 1997 01:24:40 -0800 (PST)
From: NetBlazer

Public service announcment

If you happen to be running a radiator pressure cap that says .9 on it, you will want to upgrade it to one that says 1.1 (this is bar BTW, and is equiv to 13psi cap, and 16psi cap)

I have seen quite a few .9 caps, and only a couple 1.1, and am not sure when Mazda switched.. (coolant recall?)


Date: Thu, 20 Nov 1997 07:51:00 -0600
From: "Westbrook, Chuck"

The caps were changed from 1.1 to .9 when Mazda did the coolant recall. This is also the reason people started hearing percolating noises in their cooling systems after turning off the engines. The lower pressure allows the coolant to boil at a lower temperature, and the turbo area is very hot. I never had this percolator sound until after the coolant recall.


Date: Fri, 30 Apr 1999 07:30:08 PDT
From: "Firas Arabo"

I would agree with Kyle on going with the stock t-stat next time around. According to Peter, for optimal performance the ECU wants to see a water temp reading of no less than 180. Below that point, the computer is still is warm up/protective mode. Solenoids, secondary butterflies and injectors all work as if the car was still cold. This is especially a problem on the highway since temps will drop below the 180 mark and get pretty close to 170. The difference in the minimum running temperature on the highway at around 70 mph is only about 10 degrees, and as it turns out, that's 10 degrees too cold.

Air Separation Tank (AST)


Date: Fri, 26 Mar 1999 11:31:12 -0500

Since the AST issue has surfaced again, I am re-posting an AST article I wrote last year. I have had no problems with about 4 track events so far.

The air-separation tank is in parallel with the radiator. Once the thermostat opens, the hot coolant bypasses the radiator to pass through the tank, and is returned, hot, to the waterpump inlet to re-enter the engine housing ports.

Its purpose is first to collect air/vapor in an upper, stagnant chamber. Then by thermal expansion of the fluid and gas, it purges the collected air into the vented overflow bottle by way of a 3rd hose that ends in the bottle below the coolant level. Air bubbles rise to the top and vent to the atmosphere. Upon cooling-contraction, coolant from the bottle is pulled back into the system. A probable source of the air is a little leakage, from the combustion chambers, by the o-rings.... mabe at cold start.

The coolant that flows to the separation tank comes from the top of the thermostat housing, where a mini chamber is cast into the housing. The entry into this chamber can be seen after removing the fill cap as a 10mm hole. The only chamber exit is the hose to the separation tank. The purpose of the mini-chamber is to encourage any air that is passing below, from the open thermostat to the radiator, to rise up and be sent ( with coolant ) through the small bypass line to the separation tank.

Problems With Tank Removal/Bypass line:

IMO, simple removal of the tank and splicing the lines is not recomended for two reasons: First, it provides a bypass to the radiator that is not cooled. But more importantly, it encourages any air that may collect at the top of the housing to be pushed through the engine passages when the thermostat is open. Remember that air movement to the separation tank was the primary function of the mini-chamber at the top of the thermostat housing.

A Simple Fix:

I removed the tank and installed the new cap assembly at the thermostat housing as others have done. But I also plugged the old connections (2) at the nipples and removed the hoses. This eliminated the bypass, and created a modest stagnant chamber at the top of the thermostat housing to purge out air as before with the tank. It appears to work fine, perhaps this will satisfy both pro-tank and anti-tank groups. As a final touch, I may insert an aluminum baffle to help minimize turbulance in the 'new' chamber. With this mod, the original cast mini-chamber traps coolant, so make sure it has some antifreeze for winter climates. Ideally, a small hole in the bottom of the mini-chamber would solve this little problem and add to the effective mini-AST volume.


From: Jose L. Corraliza []
Sent: Monday, March 27, 2000 7:11 AM

According to Dave (at KD Rotary), the stock AST has different chambers and baffles which serve to separate the air from the coolant.

The aluminum ASTs are, in essence, a tin can with 3 nipples welded on to it. Sure they don't split, but they don't remove the air from the system as well as the stock tanks.


Date: Sat, 22 May 1999 00:33:54 -0500
From: "Steve Wynveen" (

> The cap on the filler neck should not be a pressure cap. The overflow
> function is handled at the AST and thus needs to be a pressure cap.
> Pressure caps in both places is fine, but a normal cap on the AST woulda
> mean excessive boiling.

Let me set the record straight here. Cooling systems are a specialty area of mine, and I am quite positive that the following is correct:

In the strictest sense, both caps are "pressure caps" in that they hold pressure in the system once it warms up. However, only the cap on the AST is a pressure relief cap - the traditional type of radiator cap. You'll notice the large spring that relives pressure, and the small disk in the center that opens under vacuum to return coolant. The cap on the filler neck part of the water pump/thermostat housing only acts to seal that opening of the cooling system.

When ever your engine is running and the thermostat is open, there is coolant moving through the AST. A small volume of coolant is tapped off just past the thermostat and goes to the AST. Here it becomes nearly stagnant, and any entrained air AND vapor bubbles rise up to the surface. Coolant is then returned to the radiator, right next to the lower radiator hose outlet (leading to the water pump inlet). Coolant that flows through the AST bypasses the radiator, but that is the only way to get coolant into the AST in the first place(there is the same large pressure drop across the AST as the radiator).

The AST also acts a bit as a surge tank for the cooling system. When the water pump accelerates (with the engine), there is a certain amount of lag in getting the water flowing, due to its mass (needs to increase momentum). This can cause the water pump to cavitate because it is trying to suck water from a restrictive source - the radiator. Instead, it is able to draw down coolant from the AST, which in turn can draw in from the atmosphere (through the weakly sprung vacuum relief disk on the pressure cap). Actually, the AST draws from the overflow tank, but in this transient surge role, it really doesn't care, it just wants an easy path to get any fluid at atmospheric pressure.

There is no need to replace the cap that goes on the water pump unless the cap's rubber gasket goes bad. Also, most decent garages can test pressure caps with a special pressure cap pump, but replacing an old one is not a bad idea either.

Chris Hoke: sounds like your dealer put the caps on in the wrong spots. The cap with the pressure number and spring loaded plunger should be on the AST (the black tank by the intercooler - just to make sure there's no confusion in what the AST is). The cap with only a rubber gasket on the back side goes on the engine.

yes I am sure. I read the detail on the caps, plus just ordered replacement caps for both from Mazda Comp. Of course both need to be pressure caps, when block pressure get to point X it overflows coolant to the swirl tank (round cap with black top). this is the presurized overflow. this cap is normally higher pressure than the filler neck cap to allow water with air bubble to overflow to the swirl tank where the air separates from the coolant. A line at the bottom of this tank goes to the radiator to return coolant to the eng/rad when pressure drops a little. If the swirl tank is full and pressure exceeds it cap rating, the cap allow overflow to the NON pressurized overflow tank (a 3 part system. Cooling in the block causing suction is supposed to draw coolant back from the overflow tank to swirl tank to block when operating properly.


From: les (

While the elimination of the AST will simplify the under hood plumbing, I think you still need to worry about how the system will get rid of gasses in the system. Notice I said gasses, not air.

It is my impression that the reason Mazda went to the effort of making a fancy separation tank is because there is a chance that even 'good' engines can leak tiny amounts of exhaust into the coolant. Especially as the engine ages, and as the engine components expand and contract at different rates because of the different metals ( AL and iron ). When you have pockets of gas in the coolant, there can be hot spots that don't get the best cooling, and that can exasperate the situation.


From: Shane Baker (

The gasses are formed as a result of localized boiling, especially around the spark plugs. At least, this is what the guy who used to be on this list (and maybe still is) that designs engine cooling systems for a living told me.

The other thing that the AST does that I never hear mentioned (I wish I could remember where I read this) is act as a resevoir for the water pump to draw from to avoid cavitation since the radiator offers enough restriction to essentially starve the water pump in some conditions. I read it fairly recently, so I should be able to it.


From: Steve Cirian

Dom wrote:

>Well so far we have two failures of "bullet proof" aftermarket ASTs, an
>entire batch of incorrectly fabbed aftermarket ASTs, and countless OEM AST

The failure of the aftermarket ones is worrisome, but I think we can ignore the incorrectly fabbed ones (provided a person didn't get one of these...) in determining if an AST should be used. And I think we can ignore the OEM failures, since my personal debate was elimination vs an aftermarket one (see previous comment on worries about aftermarket ones) .

>I have yet to hear of complications arising from AST removal.

I have gotten a couple of responses that say that one issue is that they need to burp it regularly, especially at track events. This is not a complication in the sense of a failure, but is still not a "perfect" solution. Plus if there are gas bubbles in the coolant, you could get cavitation in the water pump. (that point assumes that the ASTs really do eliminate all the gasses.)


From: Dave McAnaney (

I was running my car for years with the original TriPoint AST with no problems. Being an engineer, I felt that the RX-7 designers put the AST there for a reason, so I did not eliminte it.

When I upgraded my intake and intercooler to the M2 large about a year ago, I lost the mounting point for the AST and relocated it next to the intake. Bad move - the new location was lower than the original mounting location and air pooled in the filler neck instead of the AST, causing the low coolant buzzer to go off numerous times at the track. I was constantly "burping" the system to no avail and noticing the 'sloshing water' sound in the heater core at startup.

So, I followed the majority and elminated the AST. This worked fine on the street, but once I ran on the track again I got the low coolant buzzer and 'puking coolant' out the overflow. Again, I burped the system numerous times but could not get the air out of the system. I started thinking that I may have the dreaded failing o-rings, but I did not have the other symptoms (white smoke on startup, rough idle, oil in the coolant, etc.).

I decided to un-eliminate the AST and mount it in front of the water pump at the same height as the filler cap. So far, so good. Although I have not driven the car on the track since reinstalling the AST, I have not noticed any sloshing water sounds at startup and the coolant level seems to be leveling-off. We'll see in a couple weeks at the heat of Thunderhill.

After going though all this turmoil, I have a rough theory on what's been happening in my case. As the engine ages, greater and greater amounts of air is 'blown-by' the coolant o-rings and into the coolant system, especially under sustained boost (e.g. track events). Once the engine is up-to-temp, it no longer expells any coolant or air into the overflow, so this air either settles in a high area (AST, filler neck) or gets recirculated through the system. The filler neck area can only hold a small amount of air before the trapped air is fed back into the coolant system, especially under high-rpm conditions. The AST provides a larger area out of the main coolant flow for this air to surface. Once the car is shut-off, any air trapped in the cooling system rises to the surface. If this air happens to be away from the filler neck or AST, it will remain in the cooling system and not be expelled the next time the engine is warmed-up. The AST provides an area for this air to pool to be expelled during the next warm-up cycle. [/opinion]


From: Eull, Timothy R. (

It's interesting that you should post your question at this time. I live here in Phoenix AZ and recently attended Sevenstock in Irvine CA. Prior to my departure, I installed aftermarket water and oil temp gauges (water temp plumbed on the "flat" area of the filler neck, and oil plumbed via a threaded banjo bolt just under my filter).

Anyway, on the way to the event I saw operating temps (freeway cruising at 80 mph) in the 210 to 220 range and a spike near 240F going up a hill into Palm Springs (ambient ~105F). Anyway, the entire time my stock gauge did not budge from the "middle" reading.

Once I arrived at Sevenstock several people saw that I had installed the M2 AST removal kit and expressed concern that my system might have air bubbles. Indeed it did. Unfortunately when it came to proper burping and filling of the system (including removal of the manifold hose and topping that off as well) I was totally in the dark. Also, the folks from Pettit strongly discouraged use of the elimination kit for the very reason you suggested (eliminating the system's ability to bleed air from the system).

Anyway, after winning a TriPoint AST at the event, I installed it that night in the parking garage of my hotel with the few crude tools I had brought with me, properly filled and burped the system, and headed for home the following day. On average the gauge readings I observed were 10 degrees cooler, given similar conditions, than the trip out.

Does this mean that the car will run cooler on average with the AST versus without? I'm not sure. The AST definitely gives you additional coolant capacity, but I've got to believe that a properly filled and bled system that eliminates as much air as possible will probably work just as well. My operating environment is one of the most extreme in the U.S.! For now, I'll stick with the aftermarket AST.


Date: Fri, 20 Jul 2001 07:57:46 -0600
From: dbeale (
Subject: Re: (rx7) Re: [3] Super duty AST tanks, making a new batch.

I have a Tri-point AST. It was mounted on the bracket on the PFS intercooler (which certainly looked like it blocked a lot of the air flow through that). It also had to have very long lines going to and from it.

Last month I installed the efini "Y" pipe, and removed the air pump (as I have no catalytic converters). I used the Greedy pulley kit to get the belt length issue resolved. I moved the AST to where the air pump was, and fabricated an aluminum bracket (off the air pump mounting holes). I put a hole every 1/4" or so up the bracket so I could mount it as high as possible. The lines to/from the AST are now very short. The PFS intercooler now has a clear cavity behind it (room for fans/a fan). The AST works very well in this position (the filler neck on the engine is now always almost completely full of coolant).

I think this is the best/most effective mod. (or series of mods.) I've ever done to the car. I also fab'd an aluminum bracket to support the plastic air tank on top of the engine (mostly for looks - it was supported by the "Y" pipe output plastic pipe support - I removed that ugly heavy part).


Date: Fri, 20 Jul 2001 10:42:43 -0700
From: "Mike Putnam" (
Subject: (rx7) Re: [3] Super duty AST tanks, making a new batch.

Yeiks! The AST vs. non-AST debate is beginning to look like the venerable synthetic vs. nonsynthetic oil debate. No real hard data and no likelihood of ever getting any. Just lots of anecdotal evidedence and opinions. So, here is my opinion with absolutely nothing to back it up. 8-)

First, water (or coolant in this case but lets stick with water) has air dissolved in it. You can't see it, but its there. For example a glass of water sitting on your kitchen counter contains approximately 2% air by volume. If you heat up this glass of water to lets say just below boiling about half of that air comes out of solution in the form of tiny bubbles. Pressure changes act in a similar, but opposite way - higher pressure more dissolved air, lower pressure less dissolved air. But, since on the third gen there is only a 13psi difference between a pressurized coolant system and an unpressurized system this effect is small compared to the large temperature differences experienced by the cooling system.

Well, lets get to the meat of this editorial, my guess is that the AST was not put there to remove pockets of air that remain in the system after filling it (which, in my experience, it doesn't do), but it was put there to reduce the concentration of dissolved air in the coolant. How does it do this? Remember, in the previous paragraph when water is heated (for example, as it passes through the engine) dissolve air comes out of solution as tiny air bubbles which are so small they are swept along with the flow. With an AST, these tiny air bubbles are removed before the coolant goes to the radiator. Without the AST the coolant and air bubbles go into the radiator, the fluid is cooled, and some of the tiny bubbles are reabsorbed into solution before going back into the engine, starting the process all over again. In any case, without the AST after shutdown when the engine cools all the tiny bubbles go back into solution.

So, as I see it there may be two concenquences with removing the AST and having a high level of dissolved air in your cooling system. The first one is corrosion. Air has oxygen in it, dissolved oxygen, especially at elevated temperatures, is very corrosive. Sure, your antifreeze keeps this in check for the most part, but only if you religiously change it once a year. Lowering the level of dissolved oxygen certainly could help reduce the amount of corrosion in the cooling system over the life of the engine. The second problem with air dissolved in the coolant is efficiency. Remember, as the coolant is heated by the engine the dissolved air comes out of solution in the form of tiny air bubbles. This air bubble/coolant mixture is not as efficient at removing heat as a purely liquid coolant mixture.

In conclusion, IMHO, eliminating the AST may result in a slightly increased rate of corrosion in the cooling system and a slight decrease in cooling efficiency. Since, most people will not keep their cars long enough to notice the former and a cooling system in good shape has enough excess cooling capacity to negate the latter, eliminating the AST will not have any immediate adverse effects on a well maintained cooling system. But, if you don't religiously maintain your cooling system, need every last percentage of cooling capacity you can get, or intend on keeping your car forever, it may be a good idea to keep the AST (but, certainly not the stock AST).


from les (

Stock OEM Ast's have no baffles either. I've sawed one apart before.

from les (

I don't think localized boiling would be it. Boiling water makes water vapor(steam), not air. High school physics. As soon as the water vapor (steam) cools, it collapses right back to liquid again, leaving no bubbles. When the engine cools, there would be no bubbles because of any kind of boiling.

I agree with another poster, there is trace combustion gas leakage past the O rings. The AST is designed to purge that ongoing process.


From: tworx7s (

> If there is air in the system, and the AST has been eliminated, how does
> the air get out?  Do you now have to periodically burp the system as a
> maintenance item (as you do after flushing or filling)?

Simply put one of those vent-lever caps on the remaining filler neck, instead of the generic non-thermo cap, which is basically just a lid. You can then use the vent lever to "burp" the system, but if you follow the proper procedure for filling the cooling system in the first place, you shouldn't get enough air in the system to cause potential danger. It would essentially become like any other system. HOWEVER, if you race your car and it repeatedly heeats up and cools down, you will find you'll need to burp it more often... there, there now, that's a GOOD baby :-)


from Max Cooper (

> look very sturdy and well made.  But the hoses running to / from would be
> the weak link.

The plugs you use to eliminate the AST are points of failure themselves. I popped two of those HELP! brand rubber caps before I switched to short sections of hose with bolts clamped in the ends. They are ugly, but they work. I am looking at some caps from McMaster-Carr or perhaps installing a hose from nipple to nipple with a flow restrictor in the middle.

I agree that the simplification is nice.

> Any feedback on how people are faring after doing the elimination?  Some
> people have been running w/o the AST for years now.

I lost a motor last year, but I do not think it was related to the AST elimination in any way. The new motor has been fine for >10,000 miles with no AST.

I do wonder sometimes why the car had one in stock form. Mazda did a lot of work to eliminate weight and unnecessary parts. They even moved the coils so the spark plug wires could be short and thus light. If the AST wasn't good for something, it would not have been there. My car seems to be fine without it, but these thoughts do nag me sometimes.

> If there is air in the system, and the AST has been eliminated, how does
> the air get out?  Do you now have to periodically burp the system as a
> maintenance item (as you do after flushing or filling)?

The car should be able to expell excess gas through the overflow tank. I do not ever have to burp the coolant. It has been more than 8,000 miles since I opened the filler cap.


from dbeale (

MC> I do wonder sometimes why the car had one in stock form. Mazda did a lot of
MC> work to eliminate weight and unnecessary parts. They even moved the coils so
MC> the spark plug wires could be short and thus light. If the AST wasn't good
MC> for something, it would not have been there. My car seems to be fine without
MC> it, but these thoughts do nag me sometimes.

Those who have removed it, do still have one, sort of. The space on the engine filler neck becomes the AST. Rather small, but perhaps ok.


From: Shane Baker (

> I don't think localized boiling would be it.
> Boiling water makes water vapor(steam), not air.
> High school physics.
> As soon as the water vapor (steam) cools, it collapses
> right back to liquid again, leaving no bubbles.
> When the engine cools, there would be no bubbles because
> of any kind of boiling.
> I agree with another poster, there is trace combustion gas
> leakage past the O rings. The AST is designed to purge
> that ongoing process.

You may agree with that person if you like, I'm going to stick with the person who designs cooling systems for a living :) I'm sure many of you know whom I am talking about, I just don't like to bring innocent bystanders into a thread that they didn't ask to be in.

Not another 'high school physics' debate... please... I give up :). (Sorry, just kidding, really... it just seems that somehow it is always me who is on the receiving end, whether it be someone trying to convince me that tire traction has nothing to do with contact patch size or whatever... it's kind of funny that it always happens to me).

Anyway, what you said about the steam makes sense, however, the cooling system is not filled with pure water. The chemical interactions that might take place at high temperatures with ethylene glycol and water and the various metals and whatever else might be in there are not necessarily going to revert at cooler temperatures. I'm not saying that I know what these interactions are or that they even happen, just that it's easy to suppose that they might. If nothing else, I can say that water is self ionizing and produces hydrogen ions (and hydroxide), some of which would have to produce a hydrogen gas. I am willing to go out on a limb and say, with absolution, that this is not the gas that we are trying to eliminate (I'm not a chemist, but I recall that this is not a 'popular' reaction... good thing or we'd be in trouble) and I'm only mentioning because it suggests that, while high school physics provide a valuable foundation, they are pretty much never adequate for completely explaining the real world... and it's pretty much the only thing that I know on the subject to make that point :). Like you said, we're concerned about 'gases', not 'air'. The question is, what does a boiling ethylene glycol/water/whatever solution produce? I'm not trying to condescend or anything, just further the discussion.

The exhaust gas theory is interesting, and there may be some merrit to it, I don't know.

According to 'cooling system guy', the orifice sizing of the AST is as important if not more important (I'm recalling from memory, don't blame him if I screw it up :) than the AST tank size. The orifice sizing will control the flow through the AST to both keep the fluid relatively stagnant in the tank but also (probably more importantly) to keep too much fluid from going through it because it is basically a route for coolant to travel that bypasses the radiator.

I tried to find that text that I read suggesting that the AST actually helps stop cavitation under some circumstances, but I didn't. I'll keep looking though.


Date: Wed, 28 Jan 98 19:21:00 -0500
From: Brooks Weisblat

>As I recall some of you have put Pettit Racing aluminum coolant air
>separator tank kit on your FD. Does it really help prevent coolant
>leaking? Please let me know.

I have the pettit coolant tank.....hasn't leaked yet! and I can't see it exploding since its aluminum and not plastic with a seam like the stocker...


Date: Wed, 24 Mar 1999 09:11:07 -0500
From: "Schloesser, Eric"

I purchased the Pettit AST and it came with new clamps, a new cap, and the tank.

I then needed additional hardware, (1-10mm bolt & 2-10mm nuts) and a mounting bracket.

The welds on the tank looked OK, definitely hand welded. The finish was very nice.

When I dropped it in, the mounting tab that was welded to the tank was 1" too low and about 1/2" off toward the firewall. Since it was 8:30 on a Wednesday night I ran up to get the hardware, hacksawed, drilled, and bench ground a 1/8" thick aluminum piece that I found in the garage.

Fortunately I anticipated such an event, so I was up to the fabrication work and the holes & slot lined up the first time. This really was not a big deal but ANY other after market whatever that I have installed has ALWAYS had an installation sheet to warn of these things.

I understand that Pettit possibly switched vendors, or the FAB house accidentally grabbed the wrong revision drawing, but that doesn't help someone who is hacksawing a chunk of aluminum in their garage at 9:00 on a Wednesday!


Other people said as well that Pettit has fixed some of the mounting issues as well as the requirements for "extra" parts or fabbing your own bracket. I would call them and ask for clarification on it. --Steve


Date: Tue, 03 Aug 1999 19:41:44 -0400
From: Sandy Linthicum (

I and many others have used the Pettit AST tank for years without problems. Std radiator cap works with it or you can use the fancy vented/locking cap it comes with.

The only negative is the bitching about its cost - as is clear from the recent posts nothing is really as simple as it seems and if your cooling system screws up it costs you the engine.

My opinion, the AST performs an important function on the FD and should not be eliminated. Others with equiv. experience to me have have eliminated it and have a different opinion. Take your choice.


Date: Mon, 22 Mar 1999 11:30:39 -0800
From: Mark A

Replacing the stock AST is a wise move. I was always planning on doing so but never got around to it until it was too late.

One morning I startup my 7 only to hear the coolant buzzer go off. Popped open the hood and saw coolant all over the AST. I ended up replacing my stock tank with Tri-points aluminum tank. I found Tri-points to look better than Pettits. Tri-points also uses the stock (they include a new one) AST cap instead of that standard radiator type cap. No bracket needs to be fabricated as with Pettit's. Tri-points bolts right up at the same stock location. The only thing you will need that was not included (at least with mine) is a small nut to put on the existing bolt.

One thing that was fixed by changing the leaky AST to Tri-points is the "water rushing" noise that I used to hear under the passenger side dash whenever I started up my 7 or sometime during idle was gone.


Date: Fri, 26 Mar 1999 08:05:10 -0700
From: David Beale

I just got my aluminum AST from Tripoint. It comes with the Mazda pressure release (with the spring - .9 bar) cap. Wish I knew that, could have saved the $28 Can. for the new cap I just bought. The tank is black anodized, and looks very similar to the Pettit unit in shape and size. Very well made, nice heavy mounting tab, comes with 3 ss hose clamps. Don't plan soon on building these yourself. The cap flange is intricately machined, and is actually better made than the original Mazda one. The welds on the three spigots are first rate. I've never seen the stock components under my hood (PFS intercooler and cold air intake were on the car when I got it), but the tank has a 1/8" rod sticking out the bottom. I presume this is inserted into a grommet or something on the stock intercooler parts? My only concern is the nylon fitting on the overflow spigot. The hole in it is only about 1/8". If I ever boil the coolant that sucker is going to be "tested".


Date: Wed, 7 Apr 1999 16:53:40 -0700
From: "Ulen, Robert S"

I talked to Mark at TriPoint Engineering about the caps that come on their AST. The stock 3rd gen pressure cap (Mazda P/N: N3A1-15-205A) without "ears" will work, as well as an older style cap (Mazda P/N: D316-15-205) with "ears". Both are 0.9 Kg/cm (12.8 psi), stock rated caps (do NOT put a higher pressure cap than that on).

TriPoint usually sends their AST with the "eared" cap because its a little easier to take on and off, but apparently you can have them put either on it for you. Also, when you go to replace it (in about 1 yr), you now have two factory caps to choose from, from your "friendly" Mazduh dealer.


Date: Thu, 8 Apr 1999 08:13:02 -0600
From: dbeale (

My Tripoint AST came with the "uneared" cap (must have met up with Mike Tyson).

A word of warning for those with the PFS intercooler, who have ordered the Tripoint AST. It doesn't quite fit properly. If you still want to install it, you have two choices:

1.Drill a new hole in the PFS intercooler AST mounting tab (you have to move the hole closer to the tube the tab is welded to).

2.Raise the AST so its tab rests above the PFS tab. Then make a U shaped piece to join the two (it sits over the two tabs, and when you drill holes in the right places in it you can bolt the two tabs together using the U shaped piece).

I'm using the second method, as I believe having the tank higher is a GOOD THING. This will force the "bubble" of air in the system to migrate to the AST, where it will always be forced into the overflow tank. BTW, I did check to see if the hood will clear it - it will.


Date: Thu, 8 Apr 1999 11:29:52 EDT

I also had some fit difficulties w/ the PFS IC, but by slotting the hole (in the AST, not the IC) about 3/16" in towards the body of the AST, it fit like a charm. The AST wedges tightly against the IC discharge pipe.


Ken posts regarding problems some of the older Tri-Point ASTs. Anything you buy now should have these issues fixed. Scott (Robert S. Ulen) posts further down on measurements he made on his AST. --Steve

Date: Tue, 3 Aug 1999 22:45:21 EDT

A growing body of evidence points to problems with some but not all Tri-Point Air Separator Tanks (AST's). Specifically, the dimensions of the cap housing on some Tri-Point's AST's do not meet SAE standards. This can result in the AST's cap not relieving the cooling system's pressure at the cap rating. (In my case, the pressure was not relieved by a 13-lb cap until 20-22 PSI was reached.)

One way to determine if your Tri-Point AST meets the SAE standard is to measure the distance from the top lip of the cap housing to the top of the inner hole. The SAE standard for this distance is a range of 15.53 to 16.03 mm. (My Tri-Point AST measured 14 mm). To make the measurement, put a straightedge across the top of the cap housing and drop a piece of paper down until it reaches the top of the lower hole. Then mark the paper, remove it from the cap housing and measure the distance. It will take just a few minutes to do this. For a reference point, this distance in the OEM AST measures 16 mm.

The second way to evaluate your Tri-Point AST is to conduct an actual pressure test on your cooling system. The pressure tester would be mounted on the Filler Cap housing to determine the pressure at which the AST cap activates. This, however, is not the best of tests because some caps have been shown to provide relief at the rated pressure even with a non-SAE compliant AST. Call these the "forgiving" caps. Therefore, this pressure test would only show that the AST only functions with the cap presently in use. Replacing the cap could result in the purchase of an unforgiving cap and over-pressurization of your cooling system.


Date: Tue, 3 Aug 1999 10:37:24 -0700
From: "Ulen, Robert S" (

I wanted to email you guys, and let you know what I have found so far about my TriPoint AST. It seems like the 3 of us are the most involved with this possible overpressure issue. This really concerned me, so I jumped right in to find out what is happening with my car's cooling system. The last thing I need is a failed O-ring, or some serious problem associated with coolant overpressure.

Last night, I did very careful and many measurements (for technique and repeatability) of my stock AST and the TriPoint AST. This is what I found:

Stock AST

- ----------------

TriPoint AST (mine)

- ----------------------------

Measurements of Stock 0.9 Mazda Pressure Cap (no ears, no markings, almost new)

- ---------------------------------------------------------------------------------------------------------------------------


- ------------------

This analysis says that the stock cap and the TriPoint AST should work fine together. The "pre-load" of the spring plunger is the same, which means it should relieve at its rated pressure (13 psi). The "pre-load" is a very important aspect of the integrated design. If the pre-load is more, then the required pressure to move the plunger off the seat would be higher because of more force required to move the spring.

Ken, BTW in one of your posts, you mentioned something about a "thermally activated spring". Actually, the spring is just a spring, and it is not thermally controlled like a thermostat. The plunger only moves due to pressure, and is solely dependent on the pre-load of the plunger spring, and the spring constant (which in linear in this case).

Dave, in your post to me, you said your original pressure cap had the black sticker, and had "1.3" printed on the top. Wow - that is a 18.5 psi cap. It sounds like you car has not had the coolant safety recall. If the top fitting on your filler neck is black nylon material, and not aluminum it definitely has not been done. Call Mazda Customer Service (1-800-222-5500), and give them your VIN off your car. They can tell you if their records show the recall or not.

Anyway, tonight I am borrowing a coolant system pressure tester. My plan is to install the tester/gauge on the filler neck, then start the car and record system pressure vs. coolant temperature. After the engine is totally hot, I plan on monitoring the pressure while the coolant goes through its fluctuations (195 to 230 deg F) during various fan running scenarios. Then, after I shut down the engine, I will monitor coolant temp (hot soak to approx. 245) and pressure during cooldown.

Ken, if you actually measured 14.0 mm as the neck depth on your TriPoint AST, then I would say you got a bad one. I talked to Guy at TriPoint yesterday, and asked him what the design dimension for the neck depth was. He said that the neck part of their AST is designed and manufactured by a reputable radiator manufacture. If this is the case, then I would assume that some knowledgeable engineering was put into the neck design. Based on the measurements I did on my TriPoint AST, it looks like the dimensions are very close to the SAE specs that Ken gave in one of his posts. Anyway, TriPoint seems to be looking into this issue, and it maybe entirely possible that they got a bad batch of neck made by their supplier.

I will try to pass on the pressure vs temp measurement I plan on doing tonight. That will be the true test on the function of my AST. Hope this information help get this issue resolved.


Date: Wed, 18 Aug 1999 15:53:41 -0700
From: "Ulen, Robert S" (

using TriPoint AST with OEM 0.9 Pressure Cap

I finally had a chance to conduct what I call "dynamic" pressure testing on the coolant system with the TriPoint AST using the supplied OEM Mazda 0.9 kg/cm^2 (12.8 psi) pressure relief cap. I did this by installing a temporary coolant line (replacing the stock one) between the filler neck nipple and the AST nipple. In this line was installed a calibrated pressure gauge that was "T'"-ed into the temporary line. This allowed me to monitor the pressure in the coolant system as it heated up, went through various fan operation modes, and during engine hot-soak and cooldown. Coolant temperature and pressure data was measured and recorded during these tests.

The basic results are as follows:

During warmup, the coolant pressure increased relatively rapidly upto approx. 15.4 psi maximum as the coolant expanded. Coolant pressure remained at 15.2 ~15.4 psi until the cooling fans ran for the first time @ 210 deg F (parking lights where on).

Warmup Graph

When the fans came on, the coolant pressure would drop to approx. 6 psi at fan shutoff at ~195 deg F. Note: the temperature monitor was a Type 'K' thermocouple mounted on the filler neck housing near the ECU and fan switch sensors.

Parking lights where turned off to allow the coolant temperature to go to ~228 deg F until the fans ran again. This caused the pressure cap to vent alittle more coolant since the system had not been this hot yet. Vent pressure was 15.3 psi. When the fans would run, the coolant pressure would cycle between 15.0 and 8.5 psi.

Parking lights where again turned on to bring the fan cycling back down to between 210 and 195 deg F. This caused the coolant pressure to cycle between 8.0 and 3.2 psi. This make sense, because more coolant was vented when allowed to go to ~228 in the previous step. Once coolant has left the system, it can not return until the cooling system cools enough to cause a vacuum and pull coolant back from the overflow tank. This starts to occur hours after engine shutdown as seen during the hot-soak and cooldown portion of the test.

At one point, I enabled the A/C which caused the fans to run continuously and bring the coolant temperature down to ~192 deg F. This caused the coolant pressure to dip to a low 2.3 psi. Note: feel the pressure in your AST hose sometime after the car has been hot (city driving for awhile) and fans have ran awhile with A/C on. The hose will have little pressure in it.

Fan Ops Diagram

After the fan operations test, I shut the car down when it just reached 228 deg F to get a max "hot soak". I was expecting the coolant pressure to go back up to 15.4 psi and vent some more for the first 20 minutes or so, but surprisingly the pressure started dropping almost instantly. Reason for this is because the overall "bulk" temperature of the system must drop, even though the filler neck area of the engine was increasing. Good news, is that the cooling system is not under full pressure during a hot soak.

Cooldown Chart


The TriPoint AST vents slightly higher than the rated 0.9 (12.8 psi) cap, but not too far off. If it was more than 16 psi I would get concerned. I did some more measurements of the TriPoint AST, and found that the "effective pressure area" (area that the pressure of the coolant pushes on the cap spring valve) is approx. 18 % smaller than the stock AST. This causes more pressure to be required to produce the same force on the valve spring. Note, my TP AST had a 15.5 mm seat-to-seat dimension, which is within SAE specs. Both the seat-to-seat dimension (determines relief valve pre-load) and the effective pressure area play a very important role in what pressure the cap will relieve pressure. BTW, 12.8 psi X 1.18 (18% increase) = 15.1 psi (close to what I saw). I also did "static" pressure tests with air on the TP AST before doing the "dynamic" pressure tests, that basically gave me the same ~15.0 psi vent measurement.

Running the dynamic tests also showed some interesting facts that the coolant pressure in an FD (or any car with electric fans only) will have large coolant pressure fluctuations as the bulk temperature of the coolant system changes due to fan operations.


From: Hoskinson, Jeff/EXEUG3 (
Date: Friday, September 17, 1999 2:25 PM

Well, I finally bought an AST, based purely on the wisdom of the list. I ended up buying one from from Perfomance Warehouse. I received it on Tuesday or so. My first impression was, it looked OK, quality was OK, but there were things to be desired.


  1. The nipples on the AST did not have any barbs on them. If yours don't have barbs the hoses can pop off, overtightening clamps just helps cut the hose.

  2. The filler neck has "arc" marks from welding all over it.

  3. The filler neck is not in the center of the tank.

  4. The long discussed dimension from the top of the filler neck to the inside bottom is 19.5mm. I have read that the SAE spec is 15.53-16.03mm, so it isn't in spec.

  5. I could polish this thing with a Hershey bar and get it better looking.


It has a nicely CNC'd filler neck. It could be highly polished. The weld look OK. It would probably work OK if the filler neck dimension was in spec.

So I wrote Mr. Irvine, and he said that I was the first to complain (maybe I am ultra picky, maybe I got a bad one?). He also said that his was better quality than his competitors. He would charge me a 30% "restocking fee" if I wanted to return it.

Any suggestions? So I am thinking of getting the "new and improved" Tri-Point one now. I will sell this AST to anyone for $70, it is all Al, sorta polished.


Date: Tue, 08 Feb 2000 15:51:28 -0800
From: Hernan Hernandez (

SR Motorsports offers two radiators, the Mazdacomp which is 50% ($617) larger and their own version which is 100% larger ($695).


Date: Tue, 8 Feb 2000 15:37:51 -0600
From: "Brad.Barber" (

Ray had these proprietary radiators built to his specs. The quality is the same as the Mazda Comp units, but the core is a full 2" compared to the 1 3/8" Mazda Comp piece.

The radiator is the thickest core unit on the market. For full efficiency, be sure to block any openings in your ducting to force all the air through the radiator. Many people overlook this simple trick.


Date: Thu, 30 Mar 2000 22:41:25 -0700 (MST)

There's been some interest in info about the SR Ultimate radiator, here's my $.02, I put mine in about 3 weeks ago.

Absolutely no fitment problems with the radiator itself, other than bending the radiator support tabs below (really its no big deal, took 2 mins with a pair of pliers). Very easy to install, took me 2.5 hrs (and I'm not a fast mechanic) including removal of the old radiator. Overall, I'm very impressed with the quality of the radiator.

The only place I had slight fitment problems are the I/C and intake. I have the M2 intake and the M2 large I/C. The intake is pretty easy, you just have to bend one of the tabs at the bottom so it goes around the fan bracket instead of inside it.

The IC is a bit tougher. It's not the I/C that causes the problem but rather the ducting. With the increased depth on the bigger rad., the ducting stuck up too far to allow the hood to close properly. I ended up trimming the duct to allow it to press downward against the I/C when the hood closes. That, and I now carry my hood prop rod in my trunk:-).

I don't know if this would also apply to the medium I/C, but I would think so since they are such similar designs. If I made it sound complicated, I didn't mean to, it really wasn't that bad.

I've got some pics of all this stuff on my site. Let me know if there are any other Q's.


Date: Mon, 3 Apr 2000 18:59:01 -0400
From: "kevin kelleher" (

I recall someone noted the extra 1 inch thickness offset went up, not down. Fine for the SR hood-hugger IC, but not so good for other brand large stock mounts, esp the ducting.

PF says healthy stock rad is adequate ..... mabe in perfect shape. The original mazda comp was 1.38 vs 1 inch stock core, but was narrower and had less height, so core volume was only about 25% bigger.

What is needed is 1.38 to 1.5 inch core, with front area same as stock, and all offset downward. Any bigger is overkill, imho.


Date: Sat, 11 Sep 1999 09:34:39 -0500
From: brad barber (

For you folks looking for replacement radiators... Ray Lochhead at SR Motorsports ( has the MCP unit listed at $615. You might want to check that out.

I got mine from MCP direct and had no fitment problems other than a little snip of the side piece. It was so trivial, I wouldn't call it a problem.


Date: Thu, 7 Jan 1999 19:07:51 -0500
From: Wael El-Dasher (

Pettit Racing will have a 50% larger radiator for sale in a few weeks, it will also cost less than the current 33% larger unit. Jeff informed me the 50% unit will retail for $600. Those interested should reserve one now before all will be spoken for.


Sandy lists places to get aluminum radiators. --Steve

Date: Tue, 27 Jan 98 07:09:52 -0500
From: "Linthicum, Sandy" (

>I am looking for a racing aluminum radiator for my FD.
>I know Pettit Racing sells it, but it's too expensive for me.

Mazda Competition, Griffen Radiator (on WWW) and Fluidyne (on WWW). None are inexpensive (ie. all are over $500). On the other hand, an engine rebuild is far more costly. Best intermediate step is a separate water temp guage which tells you actual operating temp (critical at road race type track events).


Date: Fri, 1 May 1998 02:28:20 -0700 (PDT)
From: NetBlazer (

Sandy was nice enough to instruct Mazda Comp to ship his $500+ radiator to me...I think I will just have to keep it :)

Actually he had it sent to me so I could verify that my ducting would in fact work with it.

I was a little dismayed to see that it is an almost exact copy of the stock radiator. I was hoping they had increased the width of the radiator, taking up the space normally occupied by foam, with core space. What they did was replace the foam with a piece of aluminum. Its possible they had a reason for this, and will find out in the morning, as I am planning on fitting it in the car then.

I did pull my stock radiator out of storage, unbolt the fans, and got out the dial calipers. The stock core is just about 1" thick, and the Mazda Comp radiator core is 1.5" thick. The end tanks are physically 2" thick, where the stock end tanks are 2" thick only at the crimp locations, and about 1.6" thick elsewhere.

I personally will most likely have my own radiator fabricated which can take advantage of the lack of an A/C condensor, PS lines, etc, but would suggest that most people use the Mazda Comp one, as it's definately a large step in the right direction.


Date: Fri, 23 Apr 1999 17:40:58 -0400 (EDT)
From: Wael El-Dasher

The Derrick Sport radiator from Cork Sport is just as good as the Mazda-comp but costs less. I haven't recieved mine yet, but I've been told it should bolt right up.


Date: Thu, 24 Jun 1999 09:42:52 -0400
From: "Ryan Schlagheck" (

The newer MazdaComp radiator, from Anthony Woodford Racing, has contoured endplates that tend to follow the edges of the frame rails better than the previous model(s).

Despite the new design, I still put in vertical ducts on either side of the radiator. This effectively keeps all intake air going through the radiator, instead of leaking around the edges. It also helps to get some of that foam weatherstrip from a home store and seal up the areas that the vertical ducts (mine are plastic - so not rattling against the radiator or chassis) don't seal.

I went a bit more extreme though, and removed the PS and AC equipment, so no condenser and PS coil in front of the radiator. I have a big hole in the engine bay that allows me to see the steering rack and road beneath the car. The hot air from the MazdaComp radiator spills into this area and exits the car.

Cooling temps with this setup is 185-195, and at WOT climbs to 210 or so. I ran up to 210 degrees on the dyno, w/ a small low-CFM fan blowing into the front of the car. Pressing the AC button on the dash still activates the fans, so temps go right back down to 195 at idle or in traffic too. Temps were measured using an Autometer electrical H2O gauge.


Date: Sun, 02 Apr 2000 19:46:37 -0700
From: Max Cooper (

I went to the International Auto Salon at the Fairplex in Pomona, CA today. This event is a big car show with lots of both cars and vendors. I was very impressed with the range of products and vendors.

* FLUIDYNE - a new radiator for the FD is listed as being scheduled for release in April 2000 in their catalog and price list. An FC radiator is listed in the catalog for July 2000 release. I wish I would have talked to them now, oops!


Date: Mon, 3 Apr 2000 21:47:29 EDT

I just called Fluidyne and they will have a drop in radiator ready for 3rd gens by the end of the month. List price will be about $530.00. I asked about a possible group buy and he seemed to like the idea. Just another option. Their number is 800-685-0123.


Date: Wed, 26 Mar 2003 09:50:06 -0500
From: "Paul Winter" (

Here is some actual rad data from a comparison I did a couple years ago

Stock rad - plastic end tanks, 1" thick, 54 core rows with 105 fins/foot of core

MazdaSpeed - all aluminum, 1 1/2" thick, 54 core rows, 110 fins/foot of core

Koyo - all aluminum, 2" thick, 64 core rows, 112 fins/foot of core

From the above it should be clear that moderate improvments will occur when going to the MazdaSpeed unit, everything else kept equal. Increasing thickness of a rad helps but there are diminishing returns for increasing thickness same as there are for increasing thickness of an IC or any other exchanger. More core rows is better and a combo of more core row and thickness is better yet. That's why the Koyo will cool the best. Fit issues need to be considered- the 2" thick Koyo can cause issues with fans and other stuff plus what has already been noted. The MazdaSpeed should always be considered as a stock replacement because it gets rid of the issue of failure of plastic end tanks- plastic isn't really a suitable material for end tanks any more than it is for ICs- its only justification is that it is cheap. The MazdaSpeed is prettier and a better fit.

But don't expect a rad to be a miracle cure for track use- it is not as many of us know from experience. As W notes, sealing is more important. The 3rd gen motor with thermostat in place is flow limited for cooling. Drilling a few holes in the t-stat, an old trick, works well and allows me to keep my T-78 running 15 lbs boost and an 8500 rpm shift point at 205 degrees or less on even sweltering summer days on track. 190-200 is more usual. Mine is a TRACK ONLY vehicle (fuel cell, full cage, etc) so if you want to consider this for a street machine that sees a lot of track use, note the following. Warmup time is increased a lot

In cold weather, operating temps may be so low that you will need to block some airflow to the rad (I cannot get over 165 in winter track sessions otherwise)

Kiss emissions control goodbye. The real reason for the 3rd gen operating temps on a stock vehicle has to be emissions- no sane engine maker goes to 226 fan temps unless forced to. Cooler motors emit more unburned HC, all else equal (which it rarely is)

Contrary to what has often been said, lower temp thermostats cannot and do not reduce operating temps by the fact that they open at a lower temp. Once a t-stat opens, that's the end of its contribution to temp control which is a warmup function, not an in use, regulating one. Some low temp thermostats I've seen have a larger volume opening (height of opening and cross section) so allow more flow - that is very probably the reason why some see reduced temps with them in use.

(My car) also has the CWC oil coolers and, as reported by others, oil temps track water temps with that setup.


Date: Tue, 4 Apr 2000 14:48:44 -0400
From: "Buras, Keith" (

Below is a quote I received last night from for a stock replacement radiator for my 93 Auto.

I was asking for a possible upgrade, but all they had was the stock replacement. The part number is 2067 and the cost is $149.34 shipped to your door. Keep in mind this quote is for an auto, but they probably have one for the manual as well.

If you get a used one, have it cleaned thoroughly.

>Hello there, and thank you for shopping with the #1 radiator store on the net. 
>We are committed to delivering 100% fit, form and function 100% of the time.
>Here at Radiator Wholesalers we believe in giving our customers the BEST
>quality at the absolute lowest possible price, 100% of the time.  We
>appreciate your business and hope that one of our 35,000 O.E.M. style
>radiators in stock will meet or exceed your demand. And remember all of our
>cont. U.S. only) .
>I have the stock replacement radiator for your car for only $149.34.  Ask for 
>part # p 2067 when ordering.
>And remember this radiator quoted above comes with a LIFETIME WARRANTY and
>is SHIPPED FREE of charge to your door. Also no tax if you are out of
>Thanks again, and we look forward to doing business,
>RADIATOR WHOLESALERS               For orders & questions call
>1-916-362-4444                                Or
>1-916-RADIATOR                 e-mail us:


Date: Mon, 14 Feb 2000 20:41:59 -0800
From: Stephen Weckesser (

The AT Cooler was integrated into the radiator on my 93 auto. I installed the Shane Radiator and an aftermarket AT cooler.

Radiator Hoses

Date: Mon, 23 Feb 98 17:43 PST

For anyone interested in replacing worn, aged, and/or petrified radiator hoses, I have come across the following.

Pegasus Racing (800.688.6946) stocks SAMCO Silicon Radiator hoses for 3rd Gen RX-7s. The 2 hose set is a direct replacment for the upper and lower large radiator hoses. Cost is $155.00 for both. The Pegasus part # is:


The catalog describes them as "Bright Blue silicon rubber construction with 3-ply reinforcement...." Temperature rating is -50degrees C to +200 degrees C.


Date: Mon, 12 Mar 2001 09:51:26 -0800
From: "Hedwig Poon" (

Got mine from Summit Racing. It's a Goodridge/Samco silicone upper/lower rad hose set:


Cost me $156. Mine's blue but I think it also came in yellow and red. Last I've heard Goodridge/Samco is stopping production due to the dwindling market for these things. BTW, my Summit part# is:



Date: Thu, 11 Feb 1999 07:35:15 -0600
From: "Steve Wynveen" (

I'm about to order up the parts to replace all the pressurized coolant hoses in the system. The only ones I'm not sure of are the two for the turbocharger. I couldn't see these from the top and didn't have the time or facilities to jack the car up (its still in storage). How hard are these two to replace, and how much of the engine needs to be torn apart to get to them?

I counted 13 hoses total. If I've missed any, let me know. I might have the in & out mixed up, but that doesn't really matter.

N3A1-15-186A    Upper radiator
N3A1-15-185A    Lower radiator
N3A1-15-183A    AST in
N3A1-15-184A    AST out
N3A1-13-681      Throttle body in
N3A1-13-691      Throttle body out
N3A1-13-692A    Throttle body out to water pump housing
N3A1-13-53X      Turbocharger in
N3A1-13-54X      Turbocharger out
FD01-61-211A    Heater core in
FD01-61-214B    Heater core in
FD01-61-212A    Heater core out
FD01-61-213B    Heater core out


Date: Wed, 17 May 2000 17:30:46 -0500
From: MT Sales (

I don't know of anyone that offers a kit in the sense of getting a discounted, bulk price, but you can easily see (and order) all of the hoses off the mazdatrix website .


Date: Tue, 28 Mar 2000 22:40:04 -0500
From: Gordon Monsen (

While I have yet to ascertain the real reliability of them, the Coolfex hose system is constructued from seamless corrugated copper tubing designed to withstand high vibration, high pressure use.

The exterior is chrome plated and it has aluminum end covers finished in aluminum or chrome, black or gold. there is a lifetime wrranty, though i haven't read it. 2 foot hose with chrome covers costs $170 and for 3 foot length, $205.

They also offer a variety of heater hoses of the same construction and finishes. I'm installing the radiator hose right now and will be installing any others that I can soon. Their number is 203-265-3617.

Turbo Coolant Hoses

Date: Thu, 13 Apr 2000 11:04:45 -0700
From: "Diep, Anh T" (

Basically this is the hose that runs from the water pump that supplies coolant for the turbos. It is well known for splitting and desperately needs to be changed. Especially on high mileage 93 cars such as mine. 94K and going.

Mine cracked and made a big coolant explosion after I turned off the car in January.

So for all you who haven't changed it yet. Now you know where it is. Go change it before you pop.

You have to remove Air Pump to get to it.

Picture of where the hose is.

(Ed.'s note: I linked to his web site so the picture shows up inline here. Here is the original link: ).


Date: Sun, 9 May 1999 07:04:07 -0700 (PDT)
From: khoi ta (

I used purosil 10mm silicone hoses for the feed and return from the turbos. also on the throttle and under the throttle body feeding to the thermostat. I have this on since June 98 and it seems to be fine; no hardening or cracking or swelling. The OEM I had on the turbos had swollen up to three times its size and was ready to burst. I'll see if the silicone line will hold up.


Date: Thu, 13 Jan 2000 17:43:55 -0500
From: Wael El-Dasher (

> I contacted Pegasus and they only
> have kits for the 2nd gen turbo.

Here is the info on the 3rd gen coolant hose kit:

Goodridge silicone radiator hose p/n GS53-Y

The Y in the part number is Yellow so substitute the Y with R for red...etc. Summit Racing should be able to get them for you. I bought mine from a local speedshop, B&B Performance (203)481-0366


Date: Wed, 05 Feb 2003 09:38:24 -0500
Subject: Re: (rx7) [3] Replacing Turbo cooling hoses

I replaced the turbo cooling hoses three years ago with Teflon Hose Assemblies w/Stainless Steel Braided Covers, still holding strong! Here is my post from what seems like centuries ago:

Due to the many requests pertaining to the Teflon Hose Assemblies with Stainless Steel Braided Covers, the supplier and part numbers are as follows:

McMaster-Carr: (330)995-550 or

Hose #52515k24 $4.53 per footClamp #54195k14 $4.40 per pack of 10 (marine grade)

Approximately one foot of hose is needed, but order 1.5 feet (little extra in case you screw up the first hose like I did). Trace the new hose along your bloating hose and cut the new hose about a half-inch shorter than OE hose. If one cuts the new hose to the same length as the OE, you will NOT have enough space/room to manuver in place. Trust me, this was the most difficult part of the job, real PITA. Before installing the hose, place the hose clamps on the hose. This will save allot of skin! Trying to maneuver the clamps in place in the when the hose is mounted is extremely difficult. Just to be safe, install four clamps per hose. I found my first time through (note I said first) that a clamp was over-tightened(oops). Once the engine got up to temp the metal expanded (popping the clamp) thus spraying coolant on the turbos. Being more careful the second time, all went well.

Water Pump

Date: Wed, 7 Jun 2000 03:13:45 +0200
From: "Bernd Kluesener" (

Here is a universal fit electric water pump:


From: Steve Cirian
Date: June 07, 2000

>I agree with Gary.  Maybe not a significant loss, but via the laws of
>thermodynamics, going from mechanical to electrical and then back to
>mechanical will definitely be less eficient than just staying mechanical.  

Agreed in terms of entropy, but in the real world it might depend more on how each was implemented. i.e.- maybe the alternator has less friction and power loss than the mechanically-driven pump. (i.e.- poorly designed mechanically-driven pump). Also, for the mechanically-driven pump you are adding an additional pulley, and more friction, plus a longer belt (i.e.- more rotating mass (kind of)).

An electrical pump would be able to be driven at a constant speed instead of varying with engine RPMs. Therefore it would require the same energy regardless of engine speed, whereas the mechnical one would rise in speed as RPMs rise and thus induce greater power loss to overcome friction and to pump more water. (I know you would probably want to pump more water at higher RPMs, but you may not need to do it at a 1:1 ratio as forced by the mechanical drive. Does anyone know if the electrical pumps can vary their RPMs, and is it tied to a heat sensor of some sort?)

Also, if the electrical pump is mounted remotely, you would have moved some heat away from the engine. This would help engine efficiency.

>If all the racers do use it, and it is for HP as opposed to some other
>performance/protection reason, then it could be something like the battery
>and the alternator are sharing the load, so that a charged battery before
>a race acts as a power supply during the race (assuming a race is short
>enough that the pump won't drain the battery and the alternator[/engine]
>will have to work to recharge it).

The drag race engines probably use a magneto. (Or am I really dating myself here?) But I am not sure if that powers anything except the ignition. The accessories could all be driven from a battery. Almost any battery should have enough juice to power the water pump, fuel pump, etc. for about 4 seconds :-)


water pump removal/replacement procedures.


Date: Mon, 11 Oct 1999 22:13:00 -0400
From: "Rob Robinette" (

See for the water pump replacement how-to.


Date: Fri, 8 Oct 1999 16:46:14 -0500
From: Steve Stover (
Subject: (rx7) [3] Coolant Leak - Waterpump? Update

The seal between the engine and water pump is shot, as is the pump mechanism. Only had about 25k miles on it - the pump was supposedly replaced around 15k miles, about 40k miles now.

There is a kit that replaces the front water pump seal and the pump mechanism, not the whole housing. Comes with the lower radiator hose, pump, gasket, and coolant sensor. The Mazda parts person seemed upset that I knew about such a thing without them having diagnosed a warranty repair. Info below:

Part No. N3Z1-15-S20
Bin      159
List     $145.81
Net      $116.65


Date: Tue, 14 Jul 1998 10:18:00 -0500
From: "Westbrook, Chuck"

You should be running a coolant mixture of 1 part antifreeze to 2 parts distilled water plus a whole bottle of RED LINE WATER WETTER.

If your engine compartment is dirty then it should be completely GUNKed when only warm and then washed down with soap and then rinsed. A clean engine is a cooler engine.

If you have used tap water in the engine for extended periods of time; then flush the cooling system first with aluminum safe cleaner, then distilled water, then add the mixture.

My temps have been about 195 in steady traffic and up to 210 in stop and go with the AC on during these hot days. The orig thermostat is still in.


Date: Wed, 24 Mar 1999 23:04:28 -0600
From: "Steve Wynveen"

I'd highly recommend Havoline's Extended Life antifreeze/coolant (orange colored). This stuff is the way to go, and nothing compares to it. It is a patent protected, silicate free formula. What this gets you is no silicate "slime" in your cooling system, longer water pump seal life, the best corrosion protection there is, and 5 year coolant life. GM puts it in nearly all their new cars, and can justify the increased coolant price from water pump warranty reduction alone.

If you do any racing or autocrossing, you probably want to run a mix to get you to the freeze protection you require in your area. Extra antifreeze reduces the heat capacity of the mixture. Otherwise, 50/50 mix should be just fine, unless your cooing system is in very bad shape.


Date: Mon, 27 Mar 2000 18:56:52 -0500
From: Wael El-Dasher (

> When attending the Rotary seminar given by Dave at KD Rotary here in PA this
> past weekend.  He specifically mentioned not to use Dexcool (orange colored)
> coolant.  I forget the reason, may have been that it was bad for the
> o-rings.

He had an engine failure and found it attacked the O-rings, chewed them and left alot of white crustation. I can't remember the mileage it took before he tore the engine apart, but I recall he said it was within a period of 1 year or so. The best source of coarse is Dave himself. Stop by their site and drop him a line.

He said it works great in piston engines as the gaskets have shown to negative reaction to it and he was able to see a few degrees drop in temp, but in rotary engines, the O-rings are too fragile and sensative. Now please remember that this is Dave's opinion and several factors could have resulted in the failure, ie it is not a scientific experiment, but due to this he urged us to stay away from Dexcool.

Before the subject comes up, I will go ahead and mention he found no difference (atleast on the street) using Redline Water Wetter. His comments were, it didn't help but didn't hurt anything either. His advice on lowering engine temps is to bore out the cooling passages in the housings, the idea is to keep it rough (ie don't go for a polished finish) to increase the surface area the coolant is in contact with the housing. He found this yields 8 to 10 degree difference. Of coarse there is also the obvious fact that aftermarket radiators are the best cooling mod...


Date: Mon, 27 Mar 2000 21:21:42 EST

Thanks for the heads-up Wael, but I'm still left wondering which type of "orange coolant" was used in this engine.

I made sure to use the Havoline Dex-Cool since it is a proven coolant and very safe on gaskets, etc...

BUT I have heard of such problems with the Prestone long-life coolant, also orange. Maybe I'll be my own "guinea pig" since my FD just turned 85k on the original motor... and the orange coolant has already been in there two years with no abnormalities noted.


Date: Tue, 28 Mar 2000 16:53:15 -0800
From: "Ulen, Robert S" (

With the recent comments about the use of Dex-Cool antifreeze in the rotary possibly causing damage, I decided to give Dave at KD Rotary a call to get the "straight story". Dave was kind of the instigator of this information during a tech seminar at KD Rotary just recently. Dave was pleasant to talk to, and was willing to share the whole story with me. This is a summary of what he had to say concerning the Dex-Cool.

The product in question was Havoline's Dex-Cool. It was not Prestone's Extended Life antifreeze. Both are orange in color, and both are phosphate and silicate free. Beyond that, who knows the "secret" chemical composition of each. Its unknown what Prestone Extended will do in a rotary. I've had it in my Toyota pickup (V6) for about a year, and the guts of the radiator still look new (looking in the filler neck).

Dave said he has rebuilt hundreds, if not a thousand of rotary engines over the years, and has come across three separate instances where the innards of the engines where coated with a "white powdery coating". It seems to cake up at places like seams on hose connections, etc. Also, the O-rings in these engines where "chewed up". Hard to say if it was a chemical degradation (doubt it), or erosion from the "white crude" being in the coolant. In one instant, the motor was one he had rebuilt, then had to tear down again about a year later, so he say the "before" and "after" results of the use of Dex-Cool.

We tried to come up with theories why it only seems to occur when used in a rotary engine. One comment was that every rotary engine on cold startup will leak a small amount of combustion gas into the coolant system to some degree. Its possible that the buildup of hydrocarbons in the coolant may have some bearing. Also, especially in the [3], there is some hot localized heat due to the turbo charger cooling loop. Plus, its unknown if water-wetter was used, and if that had any bearing.

My theory is, if this is occurring in your rotary you should be able to open the coolant system filler cap when the engine is stone cold, and see the white crud inside the walls of the coolant passages.

Safety Note: Only open the filler cap when engine is completely cold. I don't want anyone burned up on my account.


From: dave@KDR

Hey are the three following reasons and opinions for what they are worth...

The first time we had rebuilt an 87 Tll...the customer installed at home with our help and we watched him fill it with dexcool (havoline) and distilled water...six months later at the drags on a stock engine he spiked at 18 lbs and blew we tore down for him and the engine coolant ports were completely corroded...and the coolant seals showed really excessive corrosion...we were very suprised..he flushed the heater and rad...went back to prestone..

The second was a Hayes rebuilt that came to us with 8 K on it..the 3mm were done poorly and the engine failed..when we tore it down it was the same...the Hayes coolant seals were pitted terrible and the white powder all over the aluminum rotor housings...we asked the cust and he said he used dexcool and distilled water...

The third was 93 that the customer changed to dexcool at 55K miles...the engine had coolant seal failure at was the same as the other three as the coolant seals were destroyed...the engine in this one was never beat..older gentleman who maintained it religously and never over heated...all highway now what...

While we believe dexcool is a great product we believe they may be several reasons for this issue that is not prevelant in piston engines...(I ran dexcool in my 626 with never an issue...191K)... my opinions are this...

  1. Maybe the dexcool is very sensitive to the old antifreeze in system...maybe some chemical reaction if not flushed completely???

  2. The rotary by nature pushes some hydrocarbons into the coolant system on cold starts...cannot help it...they all do it..thats one reason for the ast tank and why everyones overflow bottle gets that ugly black stuff on the dipstick eventually...regardless maybe the dexcool mixed with hydocarbons causing a caustic reaction???

  3. The one main thing I have noticed is that they are all turbo the coolant takes much more extreme abuse from heat and turbos???maybe with all three issues combined it causes what we have seen...

Hope this helps...holler if any issues or questions...thanks a mill..dave@KDR


Date: Sun, 2 Apr 2000 23:42:41 -0500
From: "Steve Wynveen" (

I'm cc'ing the list on this to spread around what I know. I haven't been following the list very closely for the last few months, but thanks for prompting me on this issue. I won't get too in depth right now, but the ONLY problem with Dex-cool is that it can cause some silicone seals to take an accelerated compression set. The effect is further accelerated with high heat (roughly, 280 degF is a point to begin worrying). This comes straight from an applications engineer at Texaco (actually Equilon, the joint venture of Texaco & Shell, I believe). This is the one and only negative side effect of Dex-cool. FYI - there are 20 Million GM vehicles on the road with factory fills of Dex-cool and silicone seals in the cooling system.

All ethylene glycol coolants cause silicone rubber to take a compression set. All silicones are porous, and the coolant gets into the pours, somehow reducing the rubber's resilience. Texaco's recent research suggests that there is some sort of protection mechanism of silicone by silicates in conventional coolants (Dex-cool is silicate free). However, one thing to keep in mind is that most Japanese coolants are very low/no silicate formulations, so the factory fill may have been a no silicate coolant to start with.

Now the key questions we need to answer: are the inner coolant seals indeed silicone rubber? Mazda USA tells me it is proprietary and won't say (side note - I believe they did tell me that they are coated with Teflon, at least on a 3rd gen. I called last summer and don't remember the conversation precisely anymore). Of those that say, yes they are silicone, what evidence do they have? Second - is the Mazda factory fill a low or no silicate coolant?

I'll tell you that I worry way to much about my car, and loose too much sleep over my worries. Even though my car shows no signs of leaking o-rings, I still got a cooling system pressure tester for the weekend and tested my car. As expected, it held pressure great for over 15 mins, no leaks (although my cap is a bit weak - only holds about 10 psi). I've had Dex-cool in my car for 11,000 miles (since July '98), with no Water Wetter (which has a lot of silicates, defeating the purpose of Dex-cool. For those that insist on using it, I'd try Diesel Water Wetter with has no silicates). The one thing that worries me, is that I'd bet the inner o-rings live in metal that routinely gets over 280 degF.

Even though I will be sacrificing some aluminum protection and heat transfer, I'm switching back to conventional coolant - for now. My contact at Equilon graciously offered to put some of the said seals in their internal test if I'd send him one or two. Also, in about a month, we will have a machine at work that can test polymers and tell you what they are made of, including surface coatings. So, I need 2 - 3 new Mazda inner coolant seals. I think they are around $18 ea. from a dealer. It would sure be nice if someone out there would offer to take care of this and send them to me. Since buying a tow vehicle to support my racing addiction, I can barely afford a glass of water. The part number should be N326-10-B71A. TIA!


Date: Thu, 6 Apr 2000 17:26:59 -0700
From: "Ulen, Robert S" (

As far as ethylene glycol (EG) interaction with silicon o-rings, I would bet there is no concern here. Almost every modern engine in the world today has some type of rubber parts (o-rings, hoses, etc.), so I'm confident that EG is safe for these materials.

Recommendation is to not use propylene glycol antifreezes. There boiling point is lower than EG at the same temp and pressure. They may be fine for a low performance car, but not for the rotary. There is no known antifreeze that I know of where you can run an unpressurized system. If someone could invent that, they could get rich fast, since keeping a cooling system under pressure requires alot more design and materials effort than not.

IMHO, the best thing to do for a rotary is change the coolant *every* year. The rotary engine has lots more combustion blow-by (even with new o-rings) than a boinger, and this tends to "poison" the coolant at a high rate. Plus, the way the engine is designed, it is a virtual "electrolysis monster", meaning there are alot of iron/aluminum contact areas in the rotor housings/end and center housings. As the coolant degrades with combustion poisoning, heat and age, these areas tend to corrode first.


(what type to use)

Use distilled water. Regular tap water contains a lot of minerals that can build up over time.


Date: Thu, 15 Mar 2001 18:28:30 -0400
Subject: (rx7) (all) Chemical Treating of Tap Water 101

Tap water is supposed to be treated at our local water distribution site because there are lots of compounds/contaminants in it. Even after treatment it is prone to contamination. There was a documentary some time ago where high contents of lead was found in tap born water in the U.S and this was found to be caused by old galvanized piping that everyone used back in those days. Children were turning up sick with lead poisoning ...some were found with brain damage while others became *slow* ....that's why they changed ( or should have by now) to plastic water lines. There are lots of other contaminants usually referred to as HARDNESS ... the popular ones are Calcium (Ca++) and Magnesium (Mg++) but these can be chemically treated out. I wouldn't worry about any Ca++ and Mg++ less than 100 mg/l.


Test the tap water before attempting to treat it so that you know where you started from and you'd then have an idea of how much treatment is required.


Over treatment with Sodium Bicarbonate will cause Carbonate and Bi-carbonate contamination which is more difficult to treat. That is why treatments should be done in small quantities ie .25 lbs/barrel or .25 lbs of chemical per barrel water which can be equated to grams/gallon with 1 Oilfield bbl = 42 gallons ( not 55 gallon US drum)

Here ya go a nutshell ! ...

TEST 1 - Total Hardness testing (Calcium and Magnesium):-

You need :

  1. Versenate solution: 1 mL = 400 ppm Ca ++
  2. Hardness buffer
  3. Hardness indicator
  4. Distilled water
  5. Serological pipettes: one 10 mL and one 5 mL
  6. Titrating dish
  7. Volumetric pipettes: one 1 mL, one 2-mL, one 5 mL


  1. Pipette 1.0 mL of tap water into a titrating dish.
  2. Dilute to 50 mL with deionized water or distilled water.
  3. Add three drops of hardness buffer and two drops of hardness indicator.
  4. Titrate drop by drop with versenate solution (400) by swirling contents of while dripping versenate into the titrating dish until color of indicator changes from wine redd'ish to blue.

Calculation of Total Hardness:-

                            (cc's of standard versenate used)  x  400
Total hardness as Calcium = -----------------------------------------
                                      cc's of tap water used

TEST 2 - Determining Ca ++

You need to get the following items:

  1. Pipette: 1 mL
  2. Graduated cylinder: 5 mL
  3. Calcium indicator or Hydroxy Naphthol Blue ( chemical supply shop)
  4. Sulphuric Acid or NaOH solution: 1N ( drug store)
  5. 5 mL serological pipette
  6. Versenate solution: 1 mL = 400 mg/L Ca ++ (chemical supply shop)
  7. Titrating dish or beaker ( ceramic, glass if not plastic )
  8. Measuring scoop


  1. Pipette 1 to 2 mL of tap water into a titrating dish or beaker.
  2. Dilute with 25 to 50 mL of distilled water.
  3. Add 3 mL of Sulphuric Acid 1N (NaOH).
  4. Add one scoop of calcium indicator Hydroxy Naphthol Blue

    **If they try to sell you hardness indicator or buffer do not it..get the Hydroxy Naphthol Blue.

    If Ca ++ is present, the solution will turn pink.

  5. Titrate or drip drop by drop into sample with versenate solution to a violet colored. That's the end point.


               (cc's of standard Versenate used  X 400 ) 
Ca++ in mg/L = -----------------------------------------
                      ccs of tap water tested

eg. If you used 1 cc of tap water to test and If it took 1.8 cc's of versenate to turn the solution from pink to purple/violet then:- (1.8x400)/1 = 720 mg/L of Calcium

**Determining Magnesium is done from the results of the Calcium testing

TEST 3 - Magnesium Procedure

The total cc's of standard versenate solution used for total Hardness test minus total cc's of standard versenate used in the determination of calcium, times 243 = the mg/L magnesium.

Calculation of Mg++ = (total cc's Versenate from hardness - total cc's Versenate from hardness Ca++) x 243

Aftermarket Temperature Gauge Readings

Mike Avila did a survey of people who have temperature gauges. This shows the temperatures seen with various cooling system mods. April 28, 2000.

    Observed Temperatures            
Ambient Temp   At idle   Cruise   Med. Traffic   Hard Driving   Mix (W/C)   Sensor Location   Mods
70-80   195   185   205   237   60/40   Water pump   Radiator, IC, intake, single turbo
60-70   210   195   220   NA   50/50   T'stat housing   Radiator, IC, CWC oil coolers
60-70   210   180   190   220   60/40   T'stat housing   None
60-70   200   190   200   230   100/0   T'stat housing   Radiator, IC, radiator ducting, street port
70-80   210   190   210   230   70/30   T'stat housing   None
60-70   200   180   200   NA   80/20   Stock location   Radiator, IC, intake
Average:   205   188   205   229.25            

Stock Temperature Gauge Interpreter

Editor's note: Mike Putnam and Derek Vanditmars have instruction up on the San Diego club's web site on how to linearize the temp gauge. The rest of the posts in this section probably do not need to be read, since they are sort of the history leading up to this, and Mike's page does a great job of explaining everything. --Steve

Date: Wed, 24 May 2000 08:01:36 PDT
From: "Mike Putnam" (

The instruction on how to linearize the third generation RX-7 temperature gauge is available at:


From: "Drew" (
Subject: [3] Cooling Gauge Translator
Date: Sun, 16 Jan 2000 08:49:41 -0800

For those of you who don't know:

The FD cooling gauge is an idiot light with a needle. It doesn't move until it is too late. The rotary o-ring seals are very heat sensitive, will shred and require an engine rebuild. Accidental overheating is the #1 cause for FD engine failure.

Matt Severson programmed an inline interpreter. This gauge will actually move in relation to the engine temperature! On start up the needle will sweep the entire range so you know the gauge is working.

There are two reading settings:

  1. Where the needle will see H and C to be the entire range of temperatures likely to be seen by an engine. Something like Cold = 0C and Hot=150C. This means that the needle would normally read in the lower 1/3 of the swept area.

  2. The needle will see the center of the swept area to be normal operating temperature. Which means the needle would ride in the middle, but would actually MOVE when it gets hot or cold.


  • The use of the stock sender and gauge is retained.
  • A small box (about half the size of a pack of cigarettes) has two connectors that plugs in line on the interior wiring harness.
  • Easy install or removal.
  • Cost: $50 to $100 per unit. Depends on a reasonable volume of several dozen units. OR expect a cost of $150 per unit. Still worth it in my book, big time.


    We need the connectors from Sumitomo:

    Does somebody have a resource for this? Sumitomo sells in blocks of several thousand. But they do send out free samples in the 100-200 quantity range. Matt has the p/n number, but he can't seem to get them to send the correct samples.


    From: Max Cooper (

    Could one of these alternatives work?

    1. Require the purchaser to splice the wires together instead of using a connector. This has been okay with people for O2 sensor displays, ignition amplifiers, and turbo-timer alarm mods. Would it work for the gauge?

    2. Does Mazda sell the connectors as part of a sub-harness?

    3. Form a partnership with a vendor to get capital to buy the connectors, which has the added benefit of letting them handle the sales, too.


    Date: 16 Jan 00 16:51:08 EST
    From: Matthew Severson (

    Drew the part numbers are as follows:

    Male connector
    Female connector

    The connectors are 14-way, so I need 14 terminals for each female and male connector.

    I'll try and get the web page back up. Something simple, and I'll send you the address when I've got it up and running.

    ps. Yes, it will control the fans by turning them on @ 198 degrees F. I will incorparate the fan control as an option only, b/c it makes the circuit a little more complex. It will turn the fans on @ Medium speed.



    > 1) Require the purchaser to splice the wires together instead of using a
    > connector.

    Yes, but the PnP concept would be so much better. It doesn't cost much more, just the connectors are hard to get. They have to be very available, but I just don't know how to get them. Probably a quarter per peice.

    > 2) Does Mazda sell the connectors as part of a sub-harness?

    No. AFWCT.

    AFAIK Pettit and Tri-Point have both known about this project. But they don't come forward, I suspect they are not really interested.

    I'm thinking total production is about 25 units and not much more.


    Date: 16 Jan 00 20:43:02 EST From: Matthew Severson (

    here is a webpage i threw together...

    kind of rough... but oh well.


    From: "Drew" (
    Date: Mon, 17 Jan 2000 08:42:54 -0800

    Gotten about 5 more requests for info.

    I thinking a total production run of 100 will sell without a problem, with 25 being the absolute minimum.

    Suggestions for your webpage:

    Remove the link for Chart1 as you have it displayed on the referring page.

    Not that I want to steal your thunder. I just want the product and think it will be good for the whole.

    How much does it cost for a printed circuit board?
    How much does it cost for a connector set?

    Some people want to buy the minimum order from Sumitomo and just chalk up the excess to overhead. Would this be reasonable?

    One last thing: What makes you think you are an "amature" programmer. You stuff looks damn good to me...and I'm a programmer (or at least used to be).


    Date: Sun, 02 Apr 100 15:42:22 -0700
    From: "Andrew R. Ghali" (

    Sorry, no response yet. Thanks for pinging me, I should have followed up sooner. I'll try something different. Which connector is this in the schematics so can find it myself? I see the signal winding it's way through C1-04, X-14, X15, X-18, and C1-01 - X-14 is the only 14 pin connector, so that must be it?


    Date: Mon, 3 Apr 2000 20:21:57 -0700
    From: "Derek Vanditmars" (

    This is to the person (Umesh?) who works one floor above Sumitomo's USA office.

    The person you want to talk to is Mr. Jim Greenwalt, Components & Parts.

    I got the "Connectors for Automobiles" catalog the other day from these guys, and the cover letter indicated that this should be my first contact to call.

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