Failed the leak down test?

[wayne-o]

My front cylinder failed the leak down test with air coming out of the timming plug. What do I do next?

[RUBONE]

wayn-o,
It is possible that your head gasket is blown between the return oil hole and the combustion chamber allowing oil to be sucked in as the piston goes past it and creating the white smoke situation. Either it is blown, or your rings are broken, which should not happen unless there is some other issue going on like a piston trying to stick, etc. You will have to pull the head and inspect that gasket. If it is not blown then pull the cylinder. No other choices at this point. If it is just the gasket it is pretty straightforward. Just make sure you have good flat surfaces and enough room in the head for the cylinder to seat into it. If it is blown the compression can go down the oil return passage and directly into the crankcase. If the rings are broken squirting oil into the cylinder will momentarily stop the leakage in most cases. It will not usually stop the head gasket leak, so is a tool to narrow things down.
Good luck
Robbie

[wayne-o]

Ok, but this test was done with the piston at top dead center, so the rings were not low enough for air to come out of the head gasket, Right? if so then it must be the rings

[RUBONE]

Wayne-o,
Perhaps you need to see a sectional diagram of your engine. At top dead center your rings are still more than 1/4 inch below the top of the cylinder, and well below the joint for the head gasket. I'll just leave it at that!
Robbie

[wayne-o]

Yea I see that now, sorry I'm new to this. I guess I should pull the head and see what it is then