I just picked up a 1996 3.8L automatic Camaro and I have an issue. It's loosing coolant into the oil and quickly overheating. Now, if you remove the radiator cap and crank it over, with each revolution of the motor, coolant blows out of the radiator, which indicates that the cooling system is getting pressurized from somewhere. There is no smoke blowing out the tail pipe and it runs good, so I don't think it's the head gasket. I got the bright idea to do a compression test on it, but after burning two hours, I have the plugs removed, one cylinder tested, a mountain of frustration, and I am missing some skin. I swear to God, I have never considered pulling an engine to change the spark plugs until today.

The previous owner told me that a mechanic said it was the intake gasket, but people lie all the time.

So, is there any way for the cooling system to be pressurized if the intake gasket fails?

 

LOL! Wait until you try to put them back in!! If you are pressurizing the system that fast, I am guessing a head gasket. I don't think that there is a way for a leaking intake gasket to pressurize the cooling system. I may be wrong.

 

Oh, I can imagine how much suckage is going to be involved in putting em back in. No water in the exhaust pipe, no steam, all spark plugs are the same color, no coolant blowing out the spark plug holes when cranked. All signs are pointing to anything but a head gasket.

Also, I got to looking around the intake and I am finding all kinds of corrosion from coolant. The only mystery is how the pressure is getting to the coolant.

 

Ok I'll bit, if the pressure is not coming from a head gasket where is it coming from? An intake has no traped pressure. The water pump does a nice job moving coolant but it will not build pressure anymore then a fan will build pressure. If the car has been leaking coolant into the oil the head gasket thing is moot because the motor will not last much longer. There is a chemical reaction between antifreeze and bearing babbit. Once the bearings start flaking apart it will send metal all thru your oiling system.

Look on the bright side you most likely won't have to put those plus back in with the motor in.

Do you have a compressor? You could do a leak down test. Get an adapter and put shop air into the cyclinder and see if it build pressure.

 

Not to hijack the thread, but how long does it take that chemical reaction to occur?

 

It has to do with the concentration. The more antifreeze the faster it goes. I have know guys that repaired head gaskets only to have bearing failed 3 months later. I can only assume the antifreeze got it started. I have also had customers that came in with a knock in the motor and did not even know they had a bad intake gasket.

 

I have been a mechanic long enough to know that the breakdown takes a while, even with the damn Dexcool that GM uses. Besides, do you really think that someone would be refilling with antifreeze? It was pure water that I saw.

Only thing I can think of is blow by, pressurizing the crankcase, thus forcing the water into the radiator. I know exactly how unlikely that is, but it shows 0 signs of a head gasket. Yes, I have a compressor.

 

That kind of back pressure would push oil out ever gasket and seal on the motor. YOu could just remove the oil cap or a valve cover and see if it still builds pressure. IF your motor has that much back pressure you will need to fix that before the car would be road worthy anyway.

We just had another post about it but the first sign that a head gasket is blown is the pressurized coolant. The other signs will follow in weeks to come.

 

You are probably right and there is no way in hell I am going to be able to compression test all of the cylinders, there just isn't enough room. Since the heads are basically ready to be pulled once the intake is off, and how cheap they are, I will just go ahead and rebuild the upper part of the engine.

 

Well, I got 4 out of 6 tested.

1. = 150PSI
5. = 140PSI
2. = 180PSI
4. = 90PSI.

I think I got my answer on cylinder #4.