Diagnostic Challenge: bad head gasket

To begin I confess that I am sooo lazy, always looking for the easy way out...

Blown head gaskets in an early stage can be hard to identify. There is one scenario I have encountered over the years where it takes quite some time and effort to identify the affected area.

Apart from overheating under very specific conditions you may sometimes even find signs of chocolate shake in the engine oil. But that's it. No pressure rise in the expansion tank or radiator can be detected, no hard start/misfire after cold soak, no combustion gas detector alarm...

Only pressurizing the cooling system over night will show the refrigerant's intrusion into a cylinder(s).This takes a long time to manifest itself. Under this condition obviously refrigerant ends up in the oil but no pressure rise in the cooling system is detected with the engine running (not sure how it is possible as the combustion pressure is considerably higher, but so it happens).

I'd like to know what your diagnostic approach looks like in these cases. The main idea is to shorten diag time and still be accurate. I would really be ashamed to pull the wrong head on a V engine.

Thank you

Aw man, when I opened this thread I was really hoping you had some cool new way to check for head gaskets. :silly:

Apart from overheating under very specific conditions you may sometimes even find signs of chocolate shake in the engine oil. But that's it. No pressure rise in the expansion tank or radiator can be detected, no hard start/misfire after cold soak, no combustion gas detector alarm...

Been here too many times. I usually don't even find visible evidence of coolant in the oil.

One idea I had was to take an oil sample and send it out for testing. Blackstone or the like. The idea being that if they find coolant in the oil, it's game over. Biggest problem is testing turn around time. Cost is another. There's also other ways coolant gets into the crankcase, like recent engine work. Plus, if the customer just had an oil change, all the evidence may be gone.

I'd like to know what your diagnostic approach looks like in these cases. The main idea is to shorten diag time and still be accurate.

The only other test I have to offer is a leak down test on a suspect cylinder with the engine scalding hot. Hopefully, Mode $06 or misfire counts are there to put you on the scent of a suspect cylinder. Once you drove the vehicle like you stole it, you rip the spark plug out and get a leak down tester installed. If you're lucky, you get bubbles in the cooling system. :silly: If not, you probably burned your hands for nothing.

This has worked a couple times for me on those vehicles that I KNEW had a popped head gasket, but wouldn't fail under another conditions. Obviously, it's impractical on some engine designs. And, like most other head gasket tests, just because it passes doesn't mean the engine is fine.

I would really be ashamed to pull the wrong head on a V engine.

As a side topic, I'd like to hear from the community. Are you pulling individual heads on a V-engine for mechanical repairs?

Sorry to disappoint you....

Tyler wrote:

As a side topic, I'd like to hear from the community. Are you pulling individual heads on a V-engine for mechanical repairs?

Well, Mexico speaking.....

Though it's not recomendable in any way regarding overheating issues there are times where customers venture for the eventually cheapest option....

If there was a bank specific valve train/lifter/rocker issue I don't see a real problem.

Down here the whole warranty situation is completely different than in the U.S. and this definitely ia a mayor factor.....

For a valve train problem, yes, I'll pull one head. For a head gasket, no way Jose. (Get it? Mexico?)

Noah wrote:

(Get it? Mexico?)

Got it, Houston