My 780 has a large stove pipe in stead of an oil filler cap. Inside the metal pipe is some plastic mesh looking stuff which appears to collect oil before it goes to the throttle body. I cannot find a PCV nipple/screen. Doesn't this car need one? Is the mesh supposed to be replaced/cleaned once in a while? It looks brittle and extremely dirty. BTW, I believe there is too much crankcase pressure: rear main, front main, and small cam cover on back of motor are all leaking.
Thanks,
Klaus
--
95 854T, 88 780, 88 245, 01 A4 Audi

No-one else has responded so I'll have a crack at it. But it will be assuming that the pcv system in your B280 is similar to a B28 (Haynes says it is, but that doesn't neccessarily mean it is so).
There should be a plastic oil filler cap about 3" long. There should also be one or two vent pipes coming from the cap: one to the air inlet tubing between the throttle body and the the air filter, and possibly another smaller one going to a nipple somewhere. On the B28 the mesh inside the oil filler neck which you spoke about is retained inside the filler cap. It is held there by a perforated plastic disc which clips into the lower end of the cap.

Don't bother trying to clean the mesh. Buy a stainless steel kitchen pot scourer from your local supermarket. Get a big one. Gently push it into the filler cap. Trim off any surplus. Replace the perforated disc to keep it in place. Again, I'm assuming your B280 has a similar system to a B28.

Sorry, I've been absent from the board for a few days. Steve is correct, the "Flame Trap" on a B280 is the mesh inside the oil filler cap. I was able to re-use the one that came in my car, but I spent a decent amount of time cleaning it out. I also cleaned the 1" hose that goes from the cap to the intake manifold. This should help aleviate the high crankcase pressure.

God bless,
Fitz Fitzgerald.
--
'87 Blue 240 Wagon, 247k miles.
'88 Black 780, PRV-6, 145k miles.