I've owned my '79 240D for over two years now... and this problem started happening a couple of weeks ago: even after a short trip, there is a large puddle of engine oil on the ground, as soon as 10-15 minutes after parking the car (and the oil keeps dripping, at a decreasing speed for several hours).
I immediately found out that the oil was dripping down from the small holes on the bottom of the air filter housing, that is, coming out of the manifold intake underneath the air filter housing and being pushed through the air filter (which gets totally soaked with oil), then accumulating there and leaking out of the tiny holes.
First thing I did was to clean out the filter housing and put in a new air filter, thinking that perhaps the old filter had been clogged and thus causing the problem. No use: that same evening, same puddle of oil near the front right wheel. Next I tried changing the engine oil (perhaps the old oil was causing the problem, I thought) and, again, replacing the oil-soaked air filter with a new one. All the same, no use: the problem, apparently, is getting even worse with time.
Yesterday I took the car on a 100-mile trip on the highway. I stopped a couple of times for just a few minutes and each time there soon was a H-U-G-E puddle of oil underneath the car. After the trip I had to add
1 quart of oil to bring the level back to where it was before taking the trip.
Some time before this problem occurred, I had done a valve clearance adjustment - could there be any connection? Also, I had replaced the old air filter (a model that fit very loose) with a new one that fit more tightly (the filters I put in after that have been of the tighter kind).
The car performs great, is very powerful and sounds good...
What is going on?
Rino