[SoCal LS-L]

Originally Posted by Hocrest

I passed two of those tests with no signs of HC in the coolant when I had bad HG's. I had no exhaust/coolant crossover, nor did I have any oil/coolant crossover. It turns out that there was an external leak, with coolant escaping from the block between the exhaust manifold and oil pan.

True enough..... I was just assuming that if he had a coolant under his car he would have mentioned it (as an obvious culprit for overheating). If not, then HG causing coolant loss internally would definitely mix combustion gasses into the cooling system, as it would be leaking into the cylinders or oil where exhaust gasses could be forced in. Since there was no mention of coolant leaks under his car..... if he does have a HG issue, this is a good candidate for the block tester kit, if just to be sure before yanking the engine on his daily driver.