Thank you for the note, Klaus. In the past few weeks I searched quite a bit regarding this. Here are few things I found:


850 Oil Trap Box 850
posted by benglar on Sun Apr 20 23:02 CST 2003
..............Diagnosing a clogged oil trap box is easy: remove the oil filler cap and pull a vacuum through the 3/8" diameter black plastic vacuum hose leading to the flame trap (use a tool, not your mouth: oil vapors are bad for you). Air should flow freely through the hose. Any resistance at all indicates a clogged oil trap.............
-- Bruce / '82 244 (315k miles!), '86 745, '87 760Ti, '94 854


Oil separator, hose, flame trap 850 1990
posted by someone claiming to be Dmitri on Fri Sep 19 05:30 CST 2003
I just followed Haynes. The hardest part was to unbolt the last bolt (passenger side) that holds the intake manifold, you need a ring wrench for that. A little trick Haynes doesn't mention: when putting the manifold back (with a new gasket), start with the bolts from the middle - this way the gasket cannot be jammed. If you have enough time and confidence and don't break plastic parts around the fan, it is not so hard a job.
Yes, this hose is a part of exhaust recirculation.
Dmitri


1994 850 at repair shop...need advice 850
posted by Rule 308 on Tue Apr 26 09:17 CST 2005
5 hours is about right to change out the oil trap box.............. At 50.00 in parts it sounds a little on the light side, I alway replace the long breather hose that goes from the intake hose at the back of the motor all the way around the block to the front edge of them motor at the oil trap box. That hose is about 40-50 bucks by itself. With any luck this will fix your oil leak. When this box plugs up and does not allow the motor to vent properly it does not "break" seals but it does cause the pressure to build to the point where it blows past them. The idea is to stuff in a new box which will allow the motor to breathe properly and you will no longer have that pressure blowing past your seals. There are so many nooks and crannies on those engine blocks that it could easily take a week or more for it to quit dripping oil so do not expect it to be fixed immediately. Give it a week or so to evaluate it.
Mark