I've recently purchased a 1988 260E with 138k in overall great condition except for the horrific oil consumption. It only seems to affect the number six spark plug. The other five looked perfect whereas six was totally fouled with sludge. I guess what i'd really like to know is why the other five cylinders show no sign of oiling at least on the plugs, whereas number six burns it like mad. The only time I see any smoke is when i've coasted for some distance then come to a stop. Smoke just pours out for a few seconds then tapers off. At a quart+ for each tank of gas i'm amazed that it doesn't smoke like a crop duster all the time. I feel fairly confident I can replace the seals or even remove the head to have the guides replaced but I hate to spend money when I don't have to.

Perhaps one of the vacuum lines drawing oil thru a busted diaphragm somewhere? There are only two vacuum lines that I can see tapped directly into #6 cyl. at the intake manifold but neither run back to the engine so i'm at a loss for where it could draw oil into just that one cylinder besides the valve guides/seals.

Any tips greatly appreciated.

 

sounds more like valve stamp seals this engines are bulit profe enginesthats a first answer,secondly can you see any smoke when reving the car on statonery let me no ,,,,,,,,,MB TEC BEEN WITH MB 16YRS TILL PRESENT NAZ

 

Doesn't do it when stationary just after coasting for some distance. According to Alldata and Mitchell the only fluid that could be drawn into the #6 cylinder via the intake manifold would be tranny fluid from a busted vacuum diaphragm in the vacuum control module. I've checked and no fluid is being pulled in from any vacuum line. I'm not using tranny fluid at all but the oil is disappearing somewhere at an alarming rate.

I'll be installing new valve stem seals very soon. If that doesn't fix it i'm gonna borrow a boroscope and inspect the cylinder walls before removing the head and having the valve guides themselves replaced by a competent head shop. One would think that if the oil ring or piston wall was damaged it would smoke all the time not just after coasting for some distance.

Even with all the problems I love the way the car handles and drives. Very stout and competent a real pleasure to be in. The only car i've ever owned that didn't rock back and forth when i'm tapping my foot to the music.