intake manifold and plenum buildup on 300sdl - PeachParts Mercedes-Benz Forum

djrussell52 · #1 06-27-2010, 12:02 PM

I have a 300sdl with an oil (maybe diesel) leak from the intake manifold the result of a bad gasket. I removed the plenum and manifold to find a large amount of wet carbon/oil deposit in both units. The car is new to me (100k miles)and seems to have insufficient power as if the turbo is malfunctioning. The buildup begins at the wastegate. Is this normal, and if not, what is the likely culprit? I am also in the market for a good service manual. Any advice?
Thanks,
Murdoch

vstech · #2 06-27-2010, 12:26 PM

this is the result of the insipid egr function.
you need to remove your intake, and the crossover pipe, get all the gunk cleaned out, then disconnect the egr valve, and change the gasket that has a hole in it, to a copper or aluminum gasket that does not have a hole in it. get the exhaust out of the intake... of course only do this if your car is not emission inspected. most states do not inspect diesel vehicles. some do. be warned.

Bill Ladd · #3 06-27-2010, 01:30 PM

Do a search for "switchover valve" for your car. With the sludge buildup you're describing, that's a definite possibility for anemic power.

Tell us more about this car; your experience with diesels in general; what other diagnostics you may have performed; what lead you to suspect your turbo -- you know, the kind of stuff we would need to know to properly assess and advise you.

..and yes, do as VStech says to get rid of that damned egr. Both the 603s I've had apart looked like someone dropped a box of melted black crayons mixed with bunker fuel in the intake!!

edit: "overboost solenoid" also.