Please help diagnose a coolant leak

[pgorelik]

Greetings,

I am new to the site and am hoping that you guys can help me troubleshoot a coolant problem.

I have a 2.8L multiport FI in a 1988 Chevy Celebrity. The car has 230,000 miles on it and is beginning to have all sorts of problems. It has been leaking oil, and a few months ago I noticed a coolant leak. My suspicion was that the head gasket was failing, so without further diagnosing I took some time and replaced the head, intake manifold, plenum and all the other corresponding gaskets myself. After firing up the car I was dismayed to find out that the oil was still leaking, though now I think it's coming from the oil sensor switch, which ought to be an easy fix.

My bigger concern is the coolant leak. I did not notice it in the first 1000 miles since the gasket replacement, but suddenly it became very apparent. I lose about 1 gal of water (use to be antifreeze, but I thought there was no sense in polluting the roads) per 100 miles. The strange part is that there are NO OBVIOUS LEAKS or puddles under the car. I thought it was the heater core, but I would imagine after adding several gallons of water over a couple weeks it would show up somewhere. All I see is the dropping level in the radiator.

I've checked the manual and all the normal common sense areas. The hoses and metal pipes are old, but don't seem to leak. The heat works, the radiator is new, thermostat and seal are good, etc. Is it possible that I have a legitimate head gasket problem this time and am actually burning off all this coolant? I took all the precautions in doing the original gasket job: new stretch-to-torque bolts, proper 2 step tightening procedure, etc.

Any advice on this matter will be greatly appreciated.

Thanks.

[pocket-rocket]

Does it steam more then normal coming out of the tail pipe in the morning? If you go to Autozone and rent a cooling system pressure tester, that might help you find the leak easier. I've pumped 16lbs systems up to 20-25 lbs and audibly heard where it was leaking. Some might say "you shouldn't pump it up that high", but if you think about it, there is no reason why it shouldn't hold if it's a good system.

[pgorelik]

Thanks Pocket-Rocket,

No, it does not steam any more than normal, but it hasn't gotten very cold outside yet. I'll be really concerned if I can't fix this problem when winter comes and I have essentially pure water in my cooling system. I will give the pressure tester a go and see what that turns up.

One thing I did not mention in the original question is that I don't think the coolant is leaking into the crankcase. The oil looks fine (not frothy) and its level does not change other than the relatively slow oil leak I mentioned before.

[RedZMonte]

if you where leaking coolant into the oil you would tell right away.. the oil would look like chocolate milk and nasty.. if your where burning the coolant you would have a very noticable white cloud of smoke out the tailpipe. if it where leaking that much you should be able to see a puddle. it could only be a few things..

When you repalced the gaskets, radiator ect, i assume you had to drain the coolant right?

Sounds to me like when the coolant was added you had massive air pockets in the engine/cooling system and they are slowly bleeding out. my buddys vette was doing something simmilar untill we got all the air out, the coolant flow the the heads was hooked up wrong when he got it back from a performance shop. hooked up the coolant feed to the heads correctly and it kept taking more and more coolant, finally it "burped" the air bubbles out and now its at a normal level...

hows the engine temps? do you have a temp guage?

S

[pgorelik]

I thought it was air pockets bleeding out at first too, but after I went through the first gallon of extra coolant I began to suspect that it was something worse. Fortunately I have since rented a coolant system tester. I pumped it up to 15 PSI and heard an audible hiss and saw a puddle forming beneath the car. A very obvious pin hole in the heater hose. Should be a pretty easy fix as long as there aren't any other leaks.

Thanks for the advice! Hopefully this will take care of it.

[pocket-rocket]

Good to hear since it is a simple fix