1998 MGM. I've heard head gaskets are very very uncommon on our cars. I had an intake leaking into the valley and was told here and other places it was likely a failing intake. So I changed the intake. It's more responsive but I'm still getting white smoke although the leaking coolant into the valley seems to have stopped. Is there anywhere else this could be leaking into the cylinders?

I have white frosted spark plugs on at least cylinders 1 and 4, didn't pull the others although I probably should have. Starting the car with the coolant cap off does not perturb it like exhaust gas was getting in, and the oil does not have water in it or viceaversa.

Thanks!

Do you have low compression/power, overheat, or any other issues other than the smoke?

The power seems alright. I don't have a good compression tester and the harbor freight one I do have doesn't have the right adapter. Any advice for compression testing it right?

Is it smoke or steam? Steam is usually less and dissipates, smoke is usually more dense and hangs around. Does it happen no matter what, right after starting, or do you have to get up to temp, then it always happens, or only after idling for awhile and giving it gas (taking off from a stop light, for example)?

Are you needing to add coolant? How is oil consumption?

Most chain FLAPS will have a compression tester in their Loan-a-Tool program.

Did you ever change out the intake gaskets? To me it sounds like you're burning coolant. If the exhaust is a thick white, smells like burning sweet, and your coolant levels are dropping, your car is definitely eating it up as a snack. From what I know, '98 MGM uses a single exhaust, so unbolting the Y-pipe and checking which side the white smoke comes out can help narrow it down.

I had this problem last summer with some mostly disintegrated gaskets (and part of an intake manifold port). Replaced the gaskets and remedied the intake with some RTV. Hasn't leaked since.

What replacement intake did you use?

If you have nPI heads (standard on your car) and you used a PI intake, you quite possibly have a leak between the head's water passages and the end cylinders (1,4,5,8).