Unusual Coolant Problem (I'm actively searching!)
 

My car:

'94 R2 with a Fluidyne radiator and stock AST.

The symptoms:

I'm driving home last night and the coolant buzzer goes off. I add coolant at the filler neck and then at the reservoir. Apparently I mis-read the reservoir stick because the coolant just overflows onto my garage floor (is this normal?).

Well, this morning I go to work and the buzzer and comes on again (after a couple of minutes). I turn around and check the filler neck and it was low again! I add more coolant at the neck and notice the coolant is dripping out from the reservoir.

WAIT, THERE'S MORE!!!

Since the temps are normal, I drive to work, and the temp level seems fine. After about 30 minutes, I'm almost at work and am sitting at a red light. The buzzer comes on again! Only now, the temp indicator is DIPPING LOWER! To below the "C" mark while at idle, and then goes back up to "normal" again.

The light turns green, I continue to work (a block away) and the buzzer goes off. I pull into the parking lot and the buzzer comes on again. I shut the car off and there's coolant dripping from the reservoir.

So, what do you guys (and gals) think? My car does smoke during a cold start, but stops after a few minutes.

Thanks for the help.

it could be that when on low coolant the sensor wont be in the coolant therefore cant read properly make shore you didn't switch the ast cap and the neck (engine) cap.

The filler neck cap is labeled "Filler," and the AST cap say "...DO NOT OPEN...", so I don't think they're switched. Thanks.

As far as the temp guage going to cold, I don't know. But I do know that I had the same problem with the coolant going to the overflow and not getting drawn back into the radiator. You need to check a couple of things.
1> make sure that the hose going from the AST to the overflow is good and has no holes. Even a pinhole is enought to break the siphon needed to pull the coolant back into the system as it cools.

2>check the surface where the cap on the AST seals to the AST itself. I nick or a piece of dirt or something in there will not allow the cap to seal properly and will thus not allow coolant to be drawn back to the AST from the overflow.

Both of these things will allow the coolant to be expelled to the overflow, but will not allow it to be drawn back to the radiator as everything cools down thus resulting in an accumulation of coolant in the overflow and a shortage of coolant in the radiator / engine.

Hope this helps.

Sounds like it could either be a bad or poor-sealing cap (letting coolant into the reservoir at too low a pressure), or it could be the dreaded O-ring problem. Both have similar symptoms.

If either the cap on the AST doesn't seal, or combustion pressure is getting into the cooling system, then you get what you are seeing: not enough coolant in the engine, and too much in the reservoir, plus loss of coolant from the engine while you are driving.

The ONLY way for coolant to come out the overflow bottle when filling at the filler neck is if the AST cap is not sealing.

Thanks guys. I'll check the AST cap when I get off of work.

SPURVO, by "overflow bottle," you mean the coolant reservoir behind the passenger side headlight right?

Is there a procedure to get the AST cap to seal properly other than "turn clockwise as tight as possible"?

I had the same problem, with the Pettit AST, due to the cap not sealing properly, and some air getting into the system, also if you've just changed the Coolant in your system, I had issues like that with the stock ast when I did my radiator hoses, sometimes air gets trapped and it slowly works its way out, not healthy for the car, but as long as you don't see the water temp shoot through the roof, probhably okay as long as you get all the air out soon, and get the system to stabelize...

check the filler neck for bubbles at a cold startup. if there are bubbles coming out you could be in for a rebuild. couldn't hurt to pressure test it too.

I would agree that you probably have cap issues - make sure you check them both. I had a problem with coolant not being drawn back into the engine - coolant buzzer came on every morning but the overflow was full. I replaced the filler cap and the problem was solved. Hopefully it is that simple for you.

Replace the water level sensor, thats what cured my headache.

Check the gasket on the AST cap.

Well, I checked both the AST and filler caps and didn't see anything obvious. So I added some water and drove home with the stupid buzzer coming on intermittenly.

I got home and the coolant reservoir (overflow bottle?) is dripping. I checked the bottle and there appears to be a crack in the rubber sleeve where the tube connects to the bottle. Could this be the cause?

Thanks for all the help!!!

This problem is pretty common on this forum. It is either what others have said. I had this problem and I did everything. Replace all my caps, overflow tank, radiator, hoses, and none of it was it. Then I decided to do the final thing and did an engine rebuild and what do I see, my o-ring was toasted. If you've done everything, just hope that your engine isn't toasted. If it is, it'll be a good time to get it ported. :)

I have the same problem, I installed a new koyo radiator and alum ast. I also put on a greddy filler cap and still have overflow issues. Sometimes I drive around the neighborhood for a half hour before it happens. Not reliable, next step new engine with porting and 3mm apex seals. I just bought this car 4 months ago with 63,000 mi on it- suprised me. Too bad I love my car so much!

cold, make sure coolant is not above the dip stick mark for full.

engine warm, pressure test system ... look for leaks.

disconnect hose at ast, and make sure u can slowly suck fluid up hose from o'flow tank.

cap with spring goes on ast

I took it to the dealer to check for leaks this morning. The service manager called me back and told me I needed a new engine!

Is he BS-ing me? The car only smokes for a couple of minutes on a cold start, and the smoke doesn't have that "sweet" smell.

I doubt he is BS-ing you. You're car is showing a lot of signs of O-ring failure. Take it to another reputable place that you trust and get a second opinion. Don't just have it "checked for leaks." Have it Pressure Tested... This will give you undeniable proof one way or the other.

If the O-rings are shot, and you don't have the $$$ for a rebuild, you can look into a block welding system like CRC (lots of threads on that).

Sorry bud, it's not sounding good,
Rob

Yes, could be. If the crack allows the tube to pull air back into cooling system after shutting down & cooling off.

The cooling system should create a vacuum to draw the coolant back. It could be pulling air as well, displacing the coolant. You keep refilling and eventually overflow.

Don't get your hopes up, though.

Here's a related question:

For all of you that had these symptoms, how long did your car go on before your engine completely failed? How much mileage passed from the appearance of the symptoms to the engine failing and what is your driving style?

I'm like a lot of people here, I upgraded to a Fluidyne radiator, Samco silicon radiator hoses, aluminum AST, and Greddy filler cap, and still I see my coolant going down by a half cup every time I drive it. My temps on my DEFI water temp gauge vary while driving from 178F to 200F, with temps rising steadily during stop and go traffic. If I keep my air con on, it keeps the temps stable at 180F. I've tried everything to try to bulletproof the cooling system but I am at the end of all possible problems, other than O-ring failure. My car pulls strong still, BUT it does smoke a little for 3 minutes in the morning start only. How long do you think I have? How long was it for you before the engine died?

Assuming I need a rebuild, any recommendations?

I've heard good things and bad things about almost every engine builder, even Pineapple Racing.

Hayes Rotary build an engine for my '91 FC and I was very happy with their work. However, their reputation on this forum is spotty also.

I'd like to find a local shop.

By local, I mean in the Seattle, WA area.

Hey, thanks again for the help.

I did the "champagne bubble" test and didn't see any bubbles. The coolant was burping and overflowing the filler neck though.

Is the "champagne bubble" test conclusive? I mean if the results are good (no bubbles), then the O-Rings are OK right?

For bubble test, I cut the top off of a sprite bottle, where the threaded cap mount fits pretty nicely into the filler neck. This will catch the overflow while the engine is running so you can look for the bubbles

Hashiriya, I drove my car for three months with the failed O-ring. Drove it hard and often. It ran fine and started fine every day. Just lost 8-10 oz coolant EVERY time I drove it (exhaust gases pushing coolant out the overflow (yes, the one behind the pass headlight))

dtn, you might try going over to Bothell Import on Bothell-Everett highway and have Steve Hayes go over the car. They can put it on a lift, pressurize the cooling system, and they have an exhaust gas sniffer that can check the coolant for unburned hydrocarbons, which is probably the definitive O-ring failure test. Just call Bothell Import (425-481-3210), talk to Nate (he's the manager), tell him your car (there's been three of them in there over the last month alone), and set up an appointment.

This is such a common problem that when I need a rebuild, I want to do something to prevent it. I've read about aftermarket o-rings, metal o-ring shields, modifying the coolant passages, etc.

Anyone have any success with any of these methods to help remedy this engineering blunder? This a bigger design error than the infamous AST, IMO of course