Oil in the intake... - PeachParts Mercedes-Benz Forum

Endust · #1 12-10-2002, 09:07 AM

Hi all! I have an 81 300D non-turbo with an appetite for oil. Trying to chase down the leak I noticed a large volume of wet oil in the intake. I have the egr disconnected so its not getting sucked in through there. I pulled off the vent hose on top the air cleaner and let it puff onto my hand and theres not much there in the way of oil. I have a nearly constant wisp of bluse smoke when the engine is hot or cold but its not very much. I have heard the the vac pump can leak oil into the intake but i dont see any hoses running from the pump to the intake on my car. Any ideas?? I go through about a quart per 600 miles.

#2 12-10-2002, 11:28 AM

Lots of times there is some oil in the air filter housing. Did you replace the air filter recently? IF so did it get gunked up before 5000 miles. You may want to change the filter and then monitor the oil quantity on the filter. IF it fills up with oil within 300 miles. You got a problem.

Are you dripping oil from the car when it is running or not running. If it is dripping while it is running from the passanger side of the engine it may be the air filter drain pipe o ring that is leaking. Repace that o ring and possibly the drain pipe and make sure that it is fastened securely to the engine. Use lock washers on that fastener as the vibration can shake it loose.

As far as troubleshooting the oil that may be present in the intake I dont have any info.

But I do know that a siginificant amount of oil can be lost through the drain pipe.

Good luck

bob c

samiam4 · #3 12-10-2002, 08:14 PM

It's not uncomon to have some oil in the intake.

A 1981 will have the piere(??) style pump-not a diaphram. What your reading about oil failures of vacuum pumps is primarly diaphram pumps. Low vacuum on these is sometimes the check valve. Later 1986+ cars they tend to be grenades.
How many miles? Does it start well cold? Does it run smoothly? W123's can have quite a bit of oil leakage without getting any on the ground- does your car leak any oil.
How full do you fill the engine with oil? MB wants it in the middle of the range. "full" is actually overfilling. What type of oil do you use?
Wear limit is 300miles/quart.

Michael McGuire and fellow 1981 300d owner

Endust · #4 12-10-2002, 08:38 PM

starts right up without even when cold. The motor has 50k on a total rebuild(done by preivious owner who was a mb mech). No smoke visible while driving(in the day time). I do leave a dime size drop per day on the ground but cant find the source. The whole underside of the pass side of the engine is wet with oil. I ordered a new pan gasket today and thats going in this weekend. The wet oil all seems to be above the pan though so Im thinking perhaps the tube The Bob spoke of could be leaking. Even with the oil on the motor I still feel like im using a lot of oil. Thats why the wet intake had me worried. Is the oil drain tube from the air cleaner easy to spot?

#5 12-11-2002, 06:11 PM

It sounds like the air cleaner o ring and pipe might be the problem

The area of oil saturation is the same. I would definately change at least the o ring and make sure that the pipe is FIRMLY fastened to bracket. Ust two lock washer, one on the bolt and the other on the nut.

The problem is that the pipe is loosing oil when you are driving it. That is why you dont have a lot of oil loss on the driveway.

So Here is what to do. Change the o ring, maybe even the pipe, and replace the air filter and monitor what happens. Dont bother with the oil pan gasket yet. See if this easier remedy works first. I have been where you have been but I had a turbo and the drain pipe and air cleaner pipe were leaking. Your should be alot easier to deal with.

BOB C

samiam4 · #6 12-11-2002, 08:20 PM

It's easy to do on a non-turbo. I think you might have to loosen the a/c line & motormount bolt(only one). 3 6mm nuts in the airfilter housing, one 10mm holding the tube in place.

Remove and replace with two new o-rings. Make sure the oring grooves are clean.

You really shouldn't have much blowby on an engine with 50k. If I were in a bad mood, I'd suggest bore/piston clearance was done incorrectly by the machineshop.

Definately make sure you have NO oil leaks first. the 1983 with 150k that I drive uses virtually no oil in 3,000 miles. My 81 with 320,000 miles is in the 600/quart club.

Michael