Recently I have had my car checked for a blown head gasket because I was encountering a white smoke from the exhaust pipe. I was told it is not the head gasket so I'd like ot know what could be causing the gray smoking. Could it be the valve seals? How much would it be to get a leakdown test on the car or a compression test? I got a quote on the valve stem seals for about 200.

 

Could be piston rings too.

You can get a compression tester from AutoZone or the like for $10-$20 and do the test yourself. FYI

 

How did they "check" for a blown head gasket? If it's blown internally between one of the combustion chambers and one of the coolant passages then it would be undetectable if they just looked at it. Check for oil/gas mixed with coolant in your overlfow tank.

If it's white/blue smoke it usually is oil burning, if it's black then it's a rich condition, and if it's white/white then it usually is coolant. Worn piston rings along with worn valve guides are usual suspects when burning oil.

Does it smoke all the time? Is your car low on coolant/oil?

 

Either valve seals or piston rings. Do a compression check and see if any of the cyls is lower than the rest. Then put some oil in the cylinders and recheck. If compression goes up, the rings are gone. If it stays the same level the valve seals on that cylinder.

 

:werd:

 

man it would be really expensive to get rings replaced wouldn't it? That sounds like a "while I'm in here I might as well rebuild it" kind of thing to me.

 

pretty much. It depends on the condition of your cylinder walls. If they're all gouged up, you'd need at least a hone. If they're worse, you might need to have them bored, which would mean new oversized pistons and rings. Just do the compression test and get back to us. No need to fear the worst just yet.

 

Well, on another note, how long could the car run in it's crappy condition?

 

You can try running a slightly heavier weight oil, and see if it helps. Of course it's recommended to get the problem taken care of as soon as possible, but there are countless cars on the road that burn oil(usually driving in front of me ), and keep on going for a long time.

 

You could try putting some of that additive in your oil as well that helps to give life back to your valve seals. Just an idea. Like inspyral said, check the compression first and go from there. It's the cheapest and easiest at this point.