Coolant seal failure
 

Hi Folks, I think I have a bad coolant seal. Not sure how or why because the engine has not been overheated. Anyway, I've been trying to track down a small coolant leak. The car leaves a very small puddle of coolant on the undertray after it has gotten fully warm then cools down. It only loses maybe a 1/4 cup. I tightened the lower radiator hose which was a bit loose and changed out the pressure cap once I found that it had a 16 psi cap instead of the 13 psi cap.

These are the symptoms I'm getting now.
- small drop in coolant level after the engine is driven at full temp.
- trace white smoke after engine is fully warm.
- system does not seem to take up coolant from the overflow tank as it cools.
- trace champagne bubbles in the filler neck after the thermostat opens, increases with increased rpm.

I did a pressure test and it will hold about 14-15psi for a long time, at least when the engine is cold.

Anyway, that all sounds like a coolant seal to me. Anyone have other ideas?

Also, does anyone have the phone number or shop name for Lopie in Olympia?

Even without an overheat a coolant seal can fail. Yours doesn't sound that bad which would just indicate a small exhaust gas leak into the coolant. Are your plugs fouling at all? That's a definite sign... Your plugs can't burn off the coolant entering the combustion chambers and it fouls the plugs

is it condensation after using AC? But it does sound like a small coolant seal leak. :\

hate to say it but it does sound like a tiny coolant leak. could possibly be a "pinhole" leak, which is why there are only trace bubbles and small leakage, but all of the things you said soud eerily familiar (mine was FC).

^^Coolant leak/seal expert :lol:

The last engine that I had would overheat. It ended up being a coolant seal.

Yeah, it doesn't seem like it is very big but that would mean it just will get bigger over time. I haven't pulled the plugs to check on fouling, I'll try that. Although it runs GREAT and starts on first crank.

After doing a bit of checking today, I think that if it really does turn out to be a coolant seal failure, I'll probably have Jerry do the RR and see about getting a J-spec engine from Ray Crowe to put in. Ray said that he should have some in July. Then the only question would be to replace the turbos while i'm at it. :)

I would check out this I dont know if it works but I would give it a shot.
http://www.rotaryresurrection.com/3r..._seal_fix.html

I've had quite a few FDs, 21 to be specific. I'd really check all the hoses before pulling the motor for a rebuild. Remember there are quite a few coolant hoses on the FD. 2 for the turbos, 2 on the throttle body, heater hoses, AST hoses, radiator hoses. All or any of them can leak. The best clamps are the OEM clamps, worm drive clamps are OK for the radiator hoses but the small hoses really should have a stock style clamp. Also the steel hose nipples can corrode and allow a small leak.

Take it all apart and check every single hose. If coolant is hitting the belly pan you should be able to find the leak.

Good luck!

I've looked at that. My concern is that I'm afraid it would just clog up my rad and heater core. Even if it does work, it would be a temporary fix. If it does turn out to be a coolant seal, I think I'll just plan on biting the bullet and having the engine rebuilt/replaced.

Thanks, I'll do that. I did have a small coolant leak that I seem to have fixed (lower rad hose was loose). Since then I haven't noticed any more coolant on the undertray. Tomorrow though I'll drive it out to my office in Yelm. 30 miles each way and hopefully there will be little enough traffic that I can get it up to full temps. My biggest problem with cruising with the FD is just barely getting to 180 degrees.

BTW, the engine bay looks much better since I put in one of your battery trays that I bought used off a guy in Texas. Very nice.:)

Don't forget to check the water pump, it will do that too.

Dave,

What's the latest?

Thanks for asking.

I really don't know. I can't elicit any coolant leaks anymore. I changed some things, tightened hoses etc... and now I don't get leaks.

I still don't overheat. The overflow tank is staying at exactly the same level. I may be having the coolant level in the fill neck drop by about a 1/2 inch. I'm not noticing any white smoke.

So I don't know what the heck is going on. I tried to get the car nice and hot today. Only was able to get the temps up to about 92C on the PFC. Still, that should be plenty warm to circulate the coolant well. I'll try and drive the heck out of it tomorrow and see if I can get the temps nice and hot and then see what it does. I'm planning on going to the BSCC autocross on Sunday afternoon. Maybe if anyone is there that knows something about rotaries they can come and sniff my exhaust etc... :)

So, the bottom line is that if I do have a coolant seal leak, it must be a small one. I think I'll wait for it to be obvious before I decide to do a rebuild. In the mean time, I'm going to enjoy driving it and will get it tuned next month. I figure that if I have to rebuild the engine, I'm going to go with stock again anyway so the map should still be pretty close.

Stock ports FTW!

I'll demonstrate my ignorance by asking, what does the acronym "FTW" mean?

Dave, you are so close to me, I'm surprised you haven't seen me on the road anywhere.

i am guessing "for the win"

yep thats what it means

You ever drive Gravelly Lake? I saw a really clean black FD a few weeks ago. If you see me, you are fortunate. My car gets out of the garage around once a month if I am lucky. :lol:

I like how you can't get your car any hotter than 92c and I have a hard time keepin mine under 92c ;) That's a a FMIC does to your temps, oh and a constant "water injection" system also known as a bad coolant seal lol

Yeah, best to get that taken care of, i blew a coolant seal on my FD and it was like a fogger starting it up in the morning. It started out small like the issue you described, but a good couple of autox's later it would actually fill the chambers and seize the engine. I would probably plan on replacing it before the summer is over, but hope that it lasts longer :)

How much are you looking to pay for a JSpec engine? I'm just curious how much it costs, as my factory engine was around 5k to put in with labor.

90c is a normal temp for normal driving in the summer. Mine rarely see's over 85c with the big ass electric fan turning on at 84c

When you cold start in the morning does the exhaust smell like anything ?? Coolant leaks will have a sweet smell and white smoke. Have you looked into a dye test ? From what I understand a shop pours some sort of ultraviolet stuff in your coolant, lets it run through the whole engine and afterwards they can shine a light on it and any leak will glow. If the leak is internal this might not show up, idk I have never tried it.