PeachParts Mercedes-Benz Forum - View Single Post - '95 606 blow back from intake valve #3 cylinder

GregMN · #9 06-03-2016, 08:34 AM

I had the same problem on one of my '96 W210's.

At about 330k, the soot from the egr system had built up on the valve stems so bad that at least 1 would not close completely when the engine was cold. It would be hard to start from cold and would pop combustion gasses back into the intake manifold until it warmed up, then the valve would seal for the rest of the day. It sounded like a really bad rod knock.

I scrapped what I could off the valve stem.
With the intake manifold off and the engine running, I used a spray bottle of MMO on the valve stems. Over the coarse of 30 minutes I sprayed 2oz to 3oz of it down the intake ports with the engine speed from idle to 4000rpm. After that treatment the severity of the problem decreased significantly. I have driven it another 20k, but it really needs a valve job and the car is just not worth the trouble or expense.

When I first got the car, I tied the intake flapper open at the EGR valve, but I never installed a blocking plate from the exhaust manifold. If I had done that, the problem may not have happened.

The car consumes a lot of oil if it is driven hard / fast. I believe that the oil is leaving via the valve guide seals. There is no blow by out the oil filler cap.