so my 1980 280se (w126) has been suing tons of oil (i drove to and back from ocean shore, a 380 mile trip, round trip, and had to put 3 quarts in to keep her happy)

i was poking around, just checking her out, and opened my air filter cover, and found where my oil has been going, there is LOTS in there, everything in there is coasted, as well as about 1/16th inch sitting on the bottom.

i've been told it could be either a leak or it could be coming up directly to the air filter from some sort of breather hose that putting oil in there. any guesses or solutions?

i don't have a shop manual yet (working on it!!!!), so pics are great!

Mercedes vents the excess pressure built up under the valve covers into the air filter elements. The pressure is from the piston compressions, through worn or cracked valve stem seals which creates an oil vapor under the valve cover. There is a baffle in the valve cover, where the vent tube connects it to the air filter, that tries to recover the oil, but when the pressure is high enough, oil will make its way to the air filter housing.

but three quarts over less than 500 miles? how do i reduce/ solve this?

I don't think all the 3 quarts of oil wound up in the filter housing, but the first step would be to get the valve stem seals inspected and replaced if necessary. Then there's the matter of checking for other oil leaks (any oil in the parking place?) either through gravity or out the tailpipe.

i don't see any other leaks, but i don't have a parking spot, unfortunately, she's limited to street parking at my apartment

Once it is warm, and you are sitting at a stop sign/red light for a min, and then take off, do you see blue smoke? (you might not see it from inside). If I saw that, I would suspect valve stem seals.

Of course, a professional opinions that are in the flesh, are better than my armchair prognostications.

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09 Jetta TDI
1985 300D

i only see smoke when i REALLY punch it. (on the freeway, haven't paid a lot of attention to rpms on that one)

but, if the oil's filled my air filter, it's gonna be in my fuel anyway, therefor burning either way, right?

bengerman, if the valve stem seals are worn oil is leaking into the combustion chambers/cylinders and being burned while you drive ... that's creating the blue smoke from the exhaust pipe. As mentioned your engine likely needs new valve stem seals. How do the spark plugs look? Unless you are an experienced DIY mechanic it's probably a good idea to take your car to a reputable MB-trained tech for a diagnosis and repair estimate.

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Fred Hoelzle

This sounds like excessive blow by at the piston rings. Worn valve seals can be detected if you pull out the spark plugs and the white porcelain appears to be dark only on one side. This is oil coming into the combustion chamber with the intake charge. Worn piston rings will produce a lot of positive crankcase pressure (blow by) from compression bypassing the piston rings and usually results in a lot of oil accumulating in your air filter assy. Remove the breather hose and accelerate the engine a couple of times with a warm motor. If you see excessive smoke comming out worn or a cracked piston ring may be the problem. Sometimes old cars from the "70s or "80s with high milage will get carbon stuck rings. Ive used marine products like OMC Engine Tuner or Valve Tech (products for decarbonizing 2 stroke out board boat engines) to soak the rings overnight. Just pull out the spark plugs and spray that stuff in each cylinder untill it overflows and let it sit overnight. The main ingredient is Butylcellusolve and it dissolves carbon. The next day spin the motor to blow out the excess and put in a new set of spark plugs. I did this to a 86 BMW 635csi and saved the owner a engine rebuild. It made me look real good too because the owner was my boss at the time and the owner of the shop. He couldnt believe an $8 can of this cleaner stopped his blowby by free up the rings!

is this stuff like the seafoam i've been reading about?

All that sounds very excessive. I think you have a plugged vent.

The engine crank case needs to equlize the pressure between the atmosphere and the oil pan while the engine is turning. the pistons create vacume when cycling.

There are things you can try to diagnose your problem to evaluate and be a little informed before going to the shop.

Unhook the hose that comes from the valve cover or crankcase. Start the car look for smoke at the line, feel the end while the car is running should be pressure or vacume change the RPM and note what happens.

If your car has a pcv valve, check it to see it is free(sounds like a ball in a can when shook lightly, if not wash it in gas and try again or buy a new one) a egr valve depending on the engine style, can cause excessive crank case pressure. A plugged vacum line or vent can cause excessive crank case pressure. Valve guides dont cause high crank case pressure unless they are extremely worn like changing spark plugs every month to keep the car running.

You can also take off the oil cap on the valve cover and put your hand over the hole. Run the engine rpm up a little and you should feel slight vacum. If you feel pressure(Bad) or see lots of oil smoke coming out of the hole this is very likely ring blow bye and the above responses are likely. Im a optomist first.