Bad head gasket?

[Don in VT]

Hi,

Having just gone through the trauma of a possible head gasket leak and finding out the system was OK I would follow VetteVet's recommendation and do the testing to see if there are exhaust gasses in the coolant. Most auto repair have the test kit and the test does work.


If you have any further question you can feel free to email me.

Best Regards and Merry Christmas,

Don

[sdycke]

IMHO after doing the combustion gas in coolant test a few hundred times in a shop enviroment, it is not 100% postive. Maybe 85? And is very sensitive to clean (!) and correct test methods. I remember many times getting heads back (esp Chrysler!) from the machine shop that found cracks, albiet very small ones, that the tester did not pick up but were still the cause of overheating.

[scottfab]

Originally Posted by hihok9

I have the chance to look at a 91 motor that after running for about 20 min starts to push bubbles into the radiator, guy says it's the head gasket... does this sound familiar to anyone, and how can I check to make sure it isn't something worse like a crack... what else should I look for, check, etc... thanks!

Hiho

Have you road tested it? What are the systemic symptoms?
Does it in fact over heat?
I've always seen a few small bubbles in the high reservoir
I don't know that I'd run any other test at all till I know there is a problem.
.

[Marc Haibeck]

Because of the wet liners, a pushed back head gasket on an LT5 will initially result in coolant filling the white overflow tank to the top. As the failure progresses, exhaust gas will appear as a stream of bubbles entering the tank at idle. It's easy to observe the bubbles because the tank is semi-transparent. Finally, if HC can be detected in the overflow tank at over 20 ppm, that's the definitive diagnosis. Fuel should never be found in the coolant, not even a trace at 2 ppm.

I don't recommend DexCool because it causes the head gasket to swell. In addition I recently read that one of the organic acids in the the anti corrosion package has been identified as the cause of the intake manifold gasket failures that are so common on GM 3.8 V6 and Northstar engines. The silicone sealing rings get soft. This suggests that DexCool should not be used with silicone coolant hoses.

[LGAFF]

Owner of the company is a Callaway Corvette owner....

http://www.blockchek.com/

[Hog]

Those testers work great IMO, really quick way to see if combustion gasses are getting into the coolant.

peace
Hog

[scottfab]

The FSM indicates 14.7 gts for the system cooling capacity.

[scottfab]

Originally Posted by Dynomite

Ha....OK....say.....does the 14.7 quarts include filling (2/3 full) the plastic coolant overflow container under the passenger headlight?
.....snip..
Cliff

No, I'm sure it doesn't and I've checked the FSM.
It says nothing about doing so. I never have. I think the most
I've put in there was maybe a quart. If one were to cram 3.3 qts
in there I bet it would be full. Filling your windshield wiper tank is
a good idea but filling the overflow? dunno about that.

[phrogs]

If this motor is still in a ZR-1 could it just be burping?

I have seen plenty of air make it to the overflow when the car is burping but who knows until you can get in and look around. Check the easy stuff, if it really has an issue there should be more evidence to be found.