I have a 1981 300d with a newer motor.The motor was replaced in the late 1990's with a MB reman.I looked down into the intake and noticed that it was filled with sludge and oil.The motor only has about 100k miles on it so it seems to early to have blowby so what could cause all this oil to be in the intake?
I removed the whole air cleaner asm and the intake manifold and cleaned it.Inside the head the same sludge was coating the intake valves/chamber.I cleaned that out as best as I could but have never seen so much sludge in an engine.The car drives great and does not smoke the egr is disabled (for testing of course).I would like to know what causes this so I do not have to clean the intake out again.

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• 1989 Jeep cherokee 4x4 110k (sold)
• 1988 Porsche 924S 90k totaled
• 1988 VW Sirocco 16v 110k? (needs work)
• 1985 Volvo 745 Turbo 225k
• 1981 Mercedes 300D "Olga" 205k 100k on Mercedes factory reman motor

The EGR causes this. It feeds soot/oil laden exhaust gasses back into the intake. Disable it and enjoy a clean air intake. The euro models don't even have one. I disabled mine over 50k ago.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

ALL engines have blowby, its never too early for it.

Thanks for the info.
Its hard to believe a faulty egr would cause so much gunk in the intake.
The intake is now clean and the egr disabled.
What would be a good way to clean the sludge out of the head? Carburetor cleaner is the only thing I can think of.Would this be ok to use since it is a diesel?

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• 1989 Jeep cherokee 4x4 110k (sold)
• 1988 Porsche 924S 90k totaled
• 1988 VW Sirocco 16v 110k? (needs work)
• 1985 Volvo 745 Turbo 225k
• 1981 Mercedes 300D "Olga" 205k 100k on Mercedes factory reman motor

dont use the carb cleaner you can have a issue with a run away diesel. You have take a squirt bottle that can give a very fine mist and with the air filer top off shot some water into the intake but rev the engine. Shot same amounts of water into the intake dont drown it because you can hydrolock the engine. Use this technique at your own risk.

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1981 300d

without taking off the head you are just sending that crap into your cylinders to burn and stick to your pistons, pc's etc..

blowby and the turbo both send oil into your intake. The soot from egr accumulates in the oil from these culprits

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Its only 6 17mm bolts, remove the manifold and clean it off the engine.

"pawoSD" in post #2 is correct.





Have a great day.

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With the EGR working properly (or as designed anyway), a thick, sticky, spongey, buildup will coat the intake manifold and ports.
Still, with the EGR totally blocked off a dark oily coating will cover things after a few thousand miles, but it's not bad.

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1982 300CD Petrol/Black Leather

This really shouldn't hurt the engine any. I got my 240D about a month ago and it ports the engine blow by into the intake so it was pretty well coated in oil. While I was replacing the exhaust I took the intake manifold off and cleaned it, it's not hard to get off if you have a pretty good arm.