Oil Leaking From Air Filter Housing

MBZ, 1980, 300 CD, 154K miles, well maintained.
Situation and Question, Assistance Please.
Facts:
Diesel.
I have just driven 2K miles last week with no oil leaks and normal add oil,
and another 300 miles yesterday.
Today I drove normally around town, parked the car temporarly. Upon moving the car I observed a oil leak where the car had been. A large amount on the concrete, a puddle about 5 inches in diameter and 1/16in deep. A lot !!
It appeares to be coming from the air filter housing, for that area showed evidence of wet oil under the breather housing and associated parts.
No other leaks observed under and around the engine.
All hoses from the air filter housing to the engine were secure.
Inspecting the air filter housing, inside, wet with oil residue but no puddles, and filter showing oil on the bottom of the filter and some oil blown on the paper filter itself but not a lot.
Any ideas why oil, a lot of oil, would leak from the air filter housing.
Thanks for any help. I am traveling away from home and have about 2k miles to drive on the Interstates, so I am concerned.
John

 

such problem can only be done by visual inspection. try checking the cylinder head cover gasket too and pull out the dipstick to check if it's from there.

the car should be on a lifter and the engine running at 2000 rpm if possible.