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hydrocarbon in the coolant v/s pressure test

To cut my long story short, I had a overheated Honda Civic 95, that had its "Check Engine" light come on and also some *white smoke* from under the hood. I got the car checked at one car place, lets call this place A, and they checked for Hydrocarbons in the coolant and the number (i am not sure whay the number is) was really high and they came to conclusion that my head gasket needs to be replaced and they also found that my radiator needs to be replaced. Now, since they did not have expertise to change the head gasket, they waved me good bye suggesting that I should go somewhere else and find some help. That really got me concerned and I got to another car place, lets call this Place B.

Place B opened my cars hood and said, this needs radiator change. And I agreed. And told him about *diagnoses* from Place A. Place B said, we do not care what Place A says, All I see is a radiator change and I will start with that. Once I am done with that I will test to see if we need a gasket change or not. I said fine....

We did a radiator change, thermostat and stuff and was told that I am all set. I said, well so we do not need gasket change. Place B said NO. We don't. Place B added, that we did a pressure test on the engine it passed it. So, you are all set...

I am not sure what to make of it....

I guess the bug question in my mind is What test is more conclusive (hydrocarbon in the coolant v/s pressure test)? If anyone can help me with it, that be great....

Reply to
Vishal Pahuja
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Have never heard of detecting hydrocarbons in the coolant as a test for a leaking head gasket. Although it sounds plausable... it also sounds rather exotic... and would require some highly specialized costly gear. I think the old fashioned method... of pressurizing the system... and watching for leak-down is good. I would be satisfied with that diagnostic if your confident it was performed correctly.

Professor

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Reply to
Professor

The hydrocarbon test is more conclusive, but can be more sensitive than you really want. It tells you, yes, combustion gasses got into the coolant. Whether that happened only when the engine overheated or is happening on a continuing basis is an open question.

I am assuming the pressure test is the cooling system pressure, which only tells whether 15 psi holds okay. It is possible that combustion chamber pressures will force gasses past a weakened head gasket and lead to gradually progressive problems.

I think this is now in your hands. Both shops have done a competent job, with the first being a little more willing than the second to recommend work that may not be necessary and the second more willing to run the risk of seeing the car come back. My recommendation - after a week of driving, presuming there aren't any signs of overheating in the meantime and the idle doesn't start hunting, take the car back and ask them to check and make sure there isn't a bubble in the cooling system. It's easy to check (just a couple of minutes) and will tell the story. If there's a bubble the leakage that put the HCs in the coolant to begin with is acting up and you will need a head gasket before you can have confidence in your car again. If not, the head just lifted a bit with the heat (the same forces that cause head warping with more serious overheating) and you are okay.

Mike

Reply to
Michael Pardee

a block test or hydrocarbon test is cheap and easy, i have the kit,

50 bucks off the tool truck. only problem is, when a coolant service is done is the funnell always clean? i've seen techs use them for oil and the for coolant without cleaning. I prefer to use the cylinder leakdown test for head gasket issues. Chip
Reply to
chip

good point about cleanliness. in theory, hydrocarbon is the definitive test as some gaskets only leak when hot & under load, but as you say, that test is easily munged by bad workshop practice.

Reply to
jim beam

Yeah, I had that once when the drunken mechanic poured a quart of oil into the radiator and didn't tell me.

J.

Reply to
JXStern

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