83 300SD, oil in air filter-blowby?????!?

[RG5384]

This car runs absolutely great, starts right up, has good power, good idle, a/c works great. I could go on and on, however, i noticed that the air filter needs changing again and it is only about 1 month old. When i bought the car, i replaced the air filter because the old one had oil in it, i cleaned all the oil up and put in the new filter. I just checked it tonight and it needs a new one again. There was also a small amount of oil in the air filter housing as well. NOt a whole lot but enough to dirty several paper towels. I don't notice any excessive smoking etc, and i only notice white smoke on initial start up, and only brownish smoke on hard acceleration. I don't drive the car hard(hardly ever over 3k rpm) and the engine has about 150k on it(odometer konked at 125). Do i need to worry about the oil in the air filter or will this car go a long way more(like 100k more)? if there isn't any blue smoke do you think it even is blow by? I want this car to last a long time running how it is. Thanks
R

[h2odiesel]

If you want your SD to run like it should and last a long time you NEED to run it hard once in a while. A diesel run at low rpms on short trips builds up carbon deposits that will stick rings, clog up prechambers and coke up injectors. After a while you will notice increased blow by. Get it up to operating temp (20 minutes running under load) and put the hammer down > 4000rpm for sustained intervals under load. (classic Italian tune up!) Do this a few times a week and with regular oil changes (with good diesel oil, Delo, Delvac, or Mobil1) and good clean fuel and you'll be back to normal in 7 to 10 thousand miles. A shot of straight Diesel Purge wouldn't hurt either.

Bob D.

[can-do]

Greetings RG,

To save me time in writing this over again, do a search on vacuum pumps or by me in general and read my post about how oil ended up in my air filter housing. If compression is good then the only few items that can wet down your air filter are either worn valve stem seals, a faulty diaphragm in your vacuum pump sucking engine oil into your filter housing or worn valve guides. The Italian tune-up isn't a fix for real problems, but basically just get's rid of accumulated crude in your engine. If your problem is consistant then your solution needs to involve getting your hands dirty not mashing the diesel pedal to the floor.


Charles

[h2odiesel]

Charles,

I don't want to start an argument with you, just share hard won information with others. Although a bad vacuum diaphragm in some MBs can push oil into the air filter, an 83SD has a different style pump and vents into the timing chain vault. Worn guides produce no blow by as that section on the valve train is not subjected to compression or combustion pressures. The most likely source for blow by and oil in the air filter(The updated flat style breather hose can help) in this case is worn or stuck rings. At only 150 k mi I don't think wear is a problem. A 617.XX Diesel that is rarely operated above 3000 rpms will have excessive carbon deposits and likely stuck rings. Short of pulling it apart and cleaning things manually the only way to safely remove carbon build up is to operate the engine the way it was designed to operate. That means getting the entire engine not just the coolant up to optimum temperatures, and running near max rpm under load for sustained time periods. No harm will come to an MB diesel engine that is otherwise sound and it is very beneficial. I'll go further and say it is necessary if you want a happy diesel. Check your valve lash and chain stretch and let them run up there, they'll thank you for it!

Bob D.
73 220D 270k mi
83 300SD 255k mi
84 300SD 284k mi