Hi guys,

I think I have a blown coolant seal. I would like to have the confirmation.

Since I bought my FD last year I noticed that I have a coolant leak. I refill rarely but I need to every once in a while. The car never overheats, it runs great and it's easy to start. There is no white smoke at startup. I looked for a leak somewhere when the car was idling and warm but was not able to locate it. I could see some coolant on the front passager side under the air box and on the radiator (aluminium radiator btw). So I searched the forum and find that it was probably related to exhaust going into the coolant that overflow the tank.

I have performed the bubble test. I started the car when cold with the filler cap removed. No bubble until the termostat opened. Then bubble started with a continous flow. I guess this is the famous coolant seal problem.

Is there any other possibilities? BTW the AST is removed.

Thanks

 

Sounds like you just have a leak. If it was overflowing out of the "overflow" tank you would see it on the ground beneath the pass side air duct for the oil cooler. Replace all hoses and clamps. It is cheap and easy.

 

when in doubt, compression test

 

I think you mean pressure test

 

Actually my car is running great (except for this problem). If I have a blown coolant seal will I increase the damage by performing a pressure test?

My intend is to rebuild the engine next winter if I have to. I would like to enjoy the car this summer and not aggravate the problem.

Thanks

 

doh! thats right. In any case, i think the coolant pressure test is only up to 16 PSI or whatever your coolant system cap is rated at, and usually its 13.3 PSI or 16 if you upgraded your cap. Just dont hook it up to an air compressor and go full bore on it. As long as you keep it within the standard PSI range for your coolant system you shouldn't have to worry about much of anything i shouldnt think.

 

Good. I'm going to test it.

And what about the bubbles that I see when the thermostat opens? Could they be produced by a potential leak?

 

i would check for leaks, does not sound like a blown coolent seal to me. if the rad is stock like factory stock i would replace it.

 

i had a blown coolent seal a month ago. if it's bad enough (once it's cracked.. it will get worse pretty quickly).. the coolent will literally gush out as you crank over. the fact that you are still able to do the champagne (bubble) test and run your car means that you are ok so far... either case there's not much you can do. gl man.

 

Sounds like you may just have a bad hose/ hose connection past the thermostat. If the bubble don't start till after the thermostat opens them it is not an internal typical coolant seal failure... Otherwise it would bubble immediately and really would spit coolant over the engine bay with the cap off immediately as you turn the key.

With visible coolant on engine components I would also suspect a back hose or hose connection. Rent a coolant pressure tester like suggested above from a local auto parts store and see if you can find the leak... Sounds like a simple fix really...

 

Which cap is supposed to be on the filler neck when the AST is removed? Does the stock one located at the AST is fine or I need a FC cap?

Thanks

 

I would not drive the car in the summer heat with a coolant leak. if your intent is to rebuild just do it now it will cost u less by not damaging things further. if it overheats you may not be able to salvage anything in the motor.

Jeff

 

Here we go again with the same problem.

It's been a year since the last post. Here is an update. Last year I found a leak. I fixed it and I replaced the radiator cap. I drove the car the rest of summer without adding coolant until last month. The low level buzzer started again. I replaced the radiator hoses two weeks ago because I didn't trust the old one. Since then I'm looking for another leak.

I bought a pressure tester. I tested the radiator cap. It losts about 1 psi in 15min. Is this ok?

I also pressurized the coolant system. It losts about 4 psi in 2 hours. Is this ok? There is no trace of leak under the car. I inspected the engine bay many times and I can't find any leak.

I removed the leading spark plugs and cranked the engine after two hours of pressurized system. No coolant exits the spark plug holes.

Now I'm completely lost. The car doesn't overheat, doesn't smoke, doesn't leak, drives well, starts well, has good power... but lost coolant pressure and I need to add a bit of coolant everytime I drive it.

The overflow level seems to always be at 5 bars over the full mark. The level never seems to move.

I'm at a point that I don't care to rebuild the engine but I want to know for sure if it's the damn engine the problem before rebuilding it.

Thanks guys!

 

Check the AST.

thewird

 

My car doesn't have the AST. I'll post a video of the champagne test soon.

I have another question. Can the pressure drops if there is air traps in the system?

 

do you have a heater, have you check the heater core? i bought my car from someone that was having the same problem, he even took it to a rotary shop and they told him blown seals, well turn out to be that the heather core was leaking.

 

Here is the video of the champagne test I took tonight. Note that I don't think the cooling system was correctly bled at this point.

Don't hesitate to share your opinion.

http://www.youtube.com/watch?v=GvyPCx57ptg

 

Yes I have a heater core. I double and triple checked the carpet at the passager kick panel. The carpet is not wet and it doesn't smell coolant inside the car. Is it the way you checked it?

 

I doubt it's a coolant seal. When I blew a coolant seal the engine would run fine until it warmed up enough that the cooling system pressure released coolant into the combustion chamber of the rear rotor. Then of course it would run like trash. Once it cooled off it could be restarted.

Have you checked the turbo water hoses? You may have a leak there. If it's leaking onto the hot turbos then it will evaporate quickly. Do you see any steam when the engine is hot?

 

Oh btw the video was taken when the engine was at normal operating temperature (thermostat opened).

Yea I checked the turbo hoses and they are not leaking. There is no steam when the engine is hot.

I'm starting to think that the system is just not bled correctly since I flushed the coolant not too long ago. How many cool-hot-cool cycles does it take to bleed the system correctly?

 

the carpet on my case wasnt wet because there is a thick foam and rubber padding on the carpet, i remove the seat and all the trim on the passanger side and thats when i found the coolant under the passanger side, funny thing is i didnt smell it. also my winshield use to get sweaty after i drove the car for a while specially on really cold days, i guess the steam from the leak was making my winshield sweat.

 

these are my thoughts.

Coolant seal failures are usually pretty easy to pick out. Does the exhaust smell sweet? If not, then that's one good thing.

Also, when you're doing the champagne test, give the throttle a little blip, or whatever you're comfortable with. If it is a coolant seal failure, you should notice the bubbles get significantly larger. (see videos on youtube.)

Then the other thing to think about, you say the car has never over heated. As far as I know, the only other way to damage the coolant seals are due to corrosion or oxidation which will occur if regular coolant flushes are not performed. (once a year, minimum).

You don't have wet plugs when you turn over and pull them.. that's good!

Have you EVER noticed or seen coolant in the bay (I noticed in the original post you saw some on the rad but I mean recently?)

It also seems as though the system is not fully burped. Fill it, squeeze rad hoses, unhook the tb line, add more.. you'd be surprised how much more you can get in. Then drive it, let it cool off, top off. After 3 times, it should almost 100% be good, especially with the ast deleted.

Also, I'm not sure what you mean with your overflow tank.. whats going on exactly?

And one more question, how much coolant loss are you noticing after you've burped the system completely? I'm thinking if it's just a small amount, it could just be going to the overflow tank, and then the line that connects the overflow to the rad may be damaged.

I'm sure you've seen this 1 000 000 times but just in case:

 

Thanks for the great answer Mitchocalypse.

I'm starting to think that my problem is related to my radiator cap. Here is what I have done lately.

I noticed a coolant leak on the upper radiator hose about a month ago. It was the second leak at that location in two years. I decided to replace the silicone radiator hoses by stock hoses with stock clamps. During the process of replacing the hoses I tested the radiator cap. It held 13 psi so I reused it. I bought the cap last summer. I drove the car this way and I noticed that coolant was missing. I tried to bleed the system correctly but the low level buzzer keeps buzzing. I retested the cap. Surprise... it opens at 11 psi now.

I bought a jobber 13 psi cap this weekend. Same problem. I tested the brand new cap. It opened at 20 psi and would not hold pressure. Tomorrow I will order an OEM one and I will let you know how it is going.

 

okay get that cap on. I don't know if you are aware in whats done to delete the ast (not treating you like an idiot or anything) But I think it's entirely crucial you understand the cooling system. In the diagram I posted, where the air separator tank is, is essentially where your overflow tank is. Obviously the system needs to break the 13 psi in order to push coolant into the overflow though.

At 11 psi, more coolant should go into your overflow tank, possibly overflowing it (while operating) making you lose some coolant without you noticing?

I guess it's a possibility. I just like to play around with ideas in my head. The cooling system seems all too intuitive.




In all honesty, it doesn't sound like a seal..

 

I bought a new OEM cap (for 1987 FC, ast removed) and installed it. Still have the problem. When I drive the car on the highway, no problem. When I exit the highway and have to make stops at red light the low level buzzer turns on. When I leave the red light the low level buzzer stops.

It seems to be related to the engine rpm.

Also after a 20 minutes drive the overflow level increases of 7 bars on the overflow gauge. See pics in attachment.

Another test I have done. I put the pressure tester with no pressure instead of the radiator cap when the engine was cool. I started the engine and no spike happened on the pressure tester which makes me think that the coolant seals are fine but the overflow level when hot makes me think otherwise. On the pressure tester I noticed a bit of vacuum.