PeachParts Mercedes-Benz Forum - View Single Post - 1992 300D consuming a quart of oil every 60 miles

Maxbumpo · #15 06-17-2015, 09:15 AM

Valve stem seals are NOT your problem, if your engine went from consuming 1 qt per 2500 miles to 1 qt per 60 miles.

Let's think about this a little bit. Your engine is turbocharged. The turbocharger increases the air pressure in the combustion chamber above atmospheric pressure. Air will constantly be trying to escape from the combustion chamber, including going UP the valve stems. The only forces causing oil to flow DOWN the valve stems are gravity and wicking. Trust me, there is NO way that you can consume a qt of oil in 60 miles via the valve stems.

I think there are two other likely possibilities, already mentioned. The turbocharger, or a head gasket failure at the oil passage by the #1 cylinder. You need to pull the intake cross-over pipe to see if oil is flowing down that from the turbo, and also check the exhaust piping down-stream of the turbo. If there is no indication of oil in either place, then you need to find a way to test for the head gasket failure.