First I will say up-front: I am no genius when it comes to cars. Some of you may then say, "then why the hell do you have a high performance vehicle?!" Answer: Because I wanted one!

I have a 1993 (built 05/92) FD.

Now: I keep having to add coolant to my reservoir, every few weeks the "add coolant" light blares on after starting the car in the morning. There are no visible leakstains on my driveway, but I have noticed there is a "pressure" crack on the plastic coolant reservoir feeder tube by the starboard headlight. As if someone forced the cap on without holding their thumb underneath before doing so. Anyone who's ever put that cap (with dipstick) on knows what I'm talking about.

My hypothesis: When the engine gets hot, I.E. lots of turbo using, the coolant gets hot in the reservoir and bubbles up out of the crack near the top of the reservoir feeder tube.

I'm hoping that's all it is, and that I can just get a new reservoir tank and dipstick (which itself is a bit corroded).

Either way, can anyone give any other hypotheses as to what might be going on (again with no visible *exterior* leaks) and even if my guess isn't right, I still want to get a new reservoir tank and don't know where to look.

Thanks!

 

Let me try and break this to you nicely:

Your engine is probably on its last legs. Do you get white smoke out the tailpipe, especially paying attention when your engine is warm, then shut off for a few minutes, then restarted? When the coolant seals go (as they often do when the engine gets higher mileage), the coolant will leak into the engine and burn.

In a nutshell, the combustion chamber has 3 major kinds of internal seals:
1) Oil seal (o-rings)
2) Coolant seal (o-rings)
3) Apex seals (metal spring loaded seals)

Coolant seals will give symptoms including:
- exhaust gas bubbles in the coolant (run a champagne bubble test or have a shop test for exhaust in the coolant)
- coolant leaking into the engine chambers when the engine is stopped (leading to a puff of white smoke when it's restarted). Pressure testing the cooling system can find this
- needing to add coolant
- no visible leaks in the system

Have it checked out by a competent rotary shop. Search this forum for info (read the newbie thread at the top of this forum) about coolant seal failure.

http://www.scuderiaciriani.com/rx7/o-ring_failure.html

Dave

PS: I hope you got many nice, trouble-free miles out of the car already. If you just bought it this way at full price, the seller probably knew it had an impending engine rebuild coming and shafted you.

 

this is a good news, bad news situation

good news, your hypothesis could be correct.... its possible but ive never heard of that happening myself... it should be relatively cheap to fix if its just the coolant flowing from the crack.

bad news, your coolant o-rings are cooked causing coolant to leak into the combustion chamber... which means rebuild and $$$$$$

how many miles are on your engine? do you notice white smoke on startup? have you had your coolant system pressue checked? (id advise having that done soon)

 

damn.... posted too late

 

Some smoke on cold startup (heard that's somewhat normal if you haven't modified your ECU), nothing I've noticed on warm startup -- but will double check that now. A small "splurt" of smoke would only be noticeable with a friend standing behind me, so I will get on that.

bought the car last April with 73k miles, now have 84k. So yes -- got half a spring, a full summer, a full fall and half this winter so far trouble-free. Thanks Dave for inquiring...

Is it true Mazda Trix isn't open on the weekends?

I've called to have service scheduled with them in the past, only to get the runaround and lots of "call back in a couple of weeks".

I know these engines only tend to get ~120k if you're lucky, my car should have at least another 20k on it, no?

If not, how much exactly is "$$$$$$", NightStalker?

Thanks for the quick responses!

 

"I know these engines only tend to get ~120k if you're lucky, my car should have at least another 20k on it, no?"

No. 120k is very very lucky. 60-80k is probably average. Rebuild will run you around $3k if you have a Mazda reman swapped in without major upgrades or maintenance done while they're working. Although there are many things worth doing that push the price up some more (hose job, coolant hoses, injector cleaning, etc).

Dave

 

Well, there's only 2 ways for coolant to go - it will leak out or be burned.

The fact that there's a crack in the overflow tank is a red flag. The overflow system HAS to be air tight. As the coolant expands as it warms, the extra coolant is bled into the overflow tank by the radiator cap. As it cools, the engine sucks coolant back in from the overflow tank and into the engine. If there's a pinhole leak in the hose going to the overflow tank, the cap is left off, or there's a hole or crack on the tank, the vacuum won't hold, the extra coolant stays in the tank and the engine sucks air back in. The extra coolant could sneakily leak out of the crack onto the tire while you're driving, so you'd never see it going.

Anyhow, all I'm saying is check the easy stuff first. It's more common to have general cooling system woes than a cooked coolant seal.

Dale

 

if the line has a leak in it like dale said it will leak and not suk up coolant on cooldown. the hole in the resvivor is not that big a deal unless it is below the normal coolant level of the resivor tank. i would also look into the pressure cap on the ast. if the vac side fails and does not seal you will not draw any coolant back into the engine after cooldown. take it somewhere to get checked. the cap and system. will take like 30 min

 

So back to one of my original questions: Where can I get a new reservoir? I've looked all over the place online and can't find it. It looks like it's two pieces of white plastic. The actual tank itself and the feeder tube leading to it that gets the black cap with dipstick put on it....

 

by the way, the crack is at the very top of the feeder tube, just under where the cap goes on. If you don't put your fingers under it before putting on the cap, it's easy to see how the tube could break...

 

Ray Crowe at Malloy Mazda (1-888-533-3400) is the man to talk to for OEM parts. Or if you want to get a used one check the 3rd gen parts for sale section.

 

If that's your only crack in the overflow tank then that probably isn't the source of the leak. Since you have to keep adding coolant to the resevoir then it sounds like coolant is getting sucked out of the overflow tank when the engine cools which is how it should work. There are about 9+? coolant hoses under the hood that could be leaking if you still have the stock ones. In particular check out the two going from and to the turbos and the three under the upper intake manifold. All of those hoses have failed on me causing the symptoms you have described where your car eats coolant over time.
I would definitely check your overflow tank with an exhaust sniffer as well as do the champagne test to see if you might have an o-ring failure. When a coolant o-ring starts to fail high pressure exhaust gases with trace amounts of oil will enter the cooling system which can make your dipstick look corroded with black goo.

 

Just talked to a fellow over at a place here in SoCal called "MazdaTrix", he confirms everything mgoddard said -- I'm taking it in Friday to see what he thinks after a thorough checkup.

MazdaTrix is highly reputable...but wish me luck that they don't try to "force" a reman on me!

 

sounds like the same problem with mine at the moment..i need to refill the expansion tank once a week or so..no black gue or sludge though. Ive never heard the coolant buzzer either.

Im hoping it is something simple like a split hose or tank.

Thats a thought..have you checked your ast tank or the other similar looking tank (by the ac compressor)

i think these are well known for splitting at the seams being as they are made out of bloody cheap plastic.

 

so we're all clear, I'm talking about the "overflow tank"... I was not clear about that initially, except in saying the "reservoir by the starboard headlight".

wish me luck Friday as I go to have it checked...

I had an issue with my turbos several months ago, could hear them firing but they weren't giving me any power...full power loss after 3000 rpms...thought I was gonna have to replace them initially, but after looking under the hood realized an air connector had come loose -- simple retighten and no money to fix it.

Then I had a clutch line failure...thought initially I might have to pay lots for a clutch replacement...turned out to be the rubber hose to the master cylinder from the DOT3 reservoir...$20 fix for a braided reinforced cable (rather than the el-cheapo rubber it came with).

Hopefully my coolant issue is a similarly easily fixed problem!!!

 

Tanks:

http://www.mazdatrix.com/b8.htm

OEM: http://www.mazdatrix.com/getprice.as...m=15-35XB-N3A1
Aluminum: http://www.mazdatrix.com/getprice.asp?partnum=AST-ALUM

If thats leaking SUPER easy fix. It would take you 30-45min max to replace that. I think its only one bolt too and some easily removed hoses.

 

It does sound to me like a coolant seal has pooped itself in the motor, which sucks, and I'm sure has happened to most of us. With that said, here is what happened to me one day. I was swapping in a Fluidyne radiator and with everything hooked up, the car started, it would get hot, and puke the coolant out of the tank, and you could hear it boiling. When I diagnosed it, it appeared that the AST lines were backwards. That thing acts like a one way valve, and it was just dumping hot coolant into the puke tank. Easy switch and it was fixed. Good luck man. Just sharing my experience.
Mike

 

I also see steam illuminated by my starboard headlight at night when stopped (and no, I have ruled out the 'exhaust from other cars' possibility) -- if I get out I can smell coolant vapors -- I really do think it's evaporating from the crack in the plastic white overflow tank feeder tube under the plastic cap.

 

I have a similar problem, but I notice I have a small leak only on cold startup. Any suggestions.

 

EVLFD - you see the steam in your right headlight too at night? It *looks* really cool but I know it's not supposed to be there!

 

you know what, i never noticed any steam before. Maybe its because i have never checked for any. Is it a lot of steam? My problem is that I have to add coolant every 3-4 weeks. I just want to know why I have a coolant leak on cold startup.

 

I always assumed the steam illuminated by the headlight was from exhaust from other cars in traffic...until I noticed it being first at a stop light and AFTER being cognascent of the recent neverending coolant adding...

 

Just so you don't get off on the wrong track...(the overflow resivoir next to the passenger headlight) is NOT pressureized. There is a tube that comes out of the top of the tank and dumps to the ground, the crack in the top is of no consequense to the problem your speaking of. Where you need to be concerned is checking the system at the AST or filler cap (cold motor only for both of these) and see if there is need for coolant. You can also remove the filler cap (next to air pump) when the motor is cold. Start the car up and as it warms watch for air bubbles in the fill neck. If you don't see any then have the system pressure tested, a pin hole leak can cause you allot of grief and over heat a motor if not corrected. The steam seen around the headlight could be either from hot coolant going into the overflow tank and escaping from the crack in the resivoir, or from a pin hole leak in one of the hoses on that side of the car and that's the easyiest place for it to escape. Wish you luck, Jack

 

speaking of steam...STEAMPOWERED sucks and I hope the video game industry doesn't completely turn to online requirements even for single player games. Sorry, I know that's off topic but couldn't help but "bee eye tee sea aitch".

 

i had a real wierd coolant leak on my FD shortly after i purchased it, there is a sensor on the coolant housing with the cap that looks like a radiator cap.

the sensor is plastic and you had to look at it real carefully just after cutting the car off to see the coolant seeping from around the treads. I removed the sensor, and put gasket sealer around the treads and it stopped the leak...........

I try replacing the AST tank and then do a pressure check on the cooling system before going through the expense of replacing an engine