could someone explain/define what blowby is and how to test for it? from reading here it sounds like something that could be the cause of my oil leaking but i have no problems starting the car on the first crank, no unusual black smoke and no loss of power. thanks for the help.

What model and year do you have? It's always helpful to us to have that information in order to be of assitance.

Blowby is basically compression leaking past the rings. This will build pressure in the crankcase and allows combustion by products to contaminate the oil quickly.

In some cars the blowby will indeed cause oil leaks due to the nature of that particular crankcase ventilation system.

sorry..its an '84 300D turbo

sco b,

The five cylinder 617 engines have an oil separator in the air cleaner that is prone to dribbling oil on the driveway whenever the engine gets tired and starts experiencing blowby. The blowby seems to push more oil through the separator than it can handle. Is the engine using a considerable amount of oil?

If the engine is not using lots of oil, I would wash the engine real well and see if you can determine if the oil is indeed coming from the return pipe to the crankcase from the air cleaner.

Another thing that could cause this is the air cleaner mounts breaking, or the air cleaner not being installed into the return pipe properly.

Good luck,

My car has a 617 engine with a little bit of blowby. The engine likes to dribble on the street in front of my house, but it runs great so it is not a big problem. What I do to combat to dripping is clean the air filter enclosure. About once every two or three weeks I remove the air filter and wipe all of the oil away. This seems to curb the dripping to some extent.

If your engine starts right up and has sufficient power it will probably continue to run for some time.

__________________
Ben

The MBs:
1976 300D (W115) - 330K and still going (sort of)
1991 300D 2.5 Turbo - Sold at 221K
1983 280SEL - Sold at 206K
1981 300SD - Sold at 232K

i finally got to the bottom of my leak. as far as i know, it was not the blow by problem and i'm relieved. there was some gasket that needed replacing and they found a leaky fuel hose. grand total of 99$. i think i finally found an honest shop that happens to be around the corner of my house.

thanks for your help.