What's the piece on the oil filler cap and what is its purpose?

Picture insn,t that clear. But if you are talking about the round filter at right

angle to the cap. It,s a after market filter that is trying to filter grank case

pressure and fumes. Not very well!!!! I had one like it ,it blew oil mist all over the

top of the engine. If you are looking to vent and filter the crankcase go to a VW

shop and get a remote one there. Vent from PCV valve into remote ,vent it into top

of air cleaner. Oh yes don,t forget to remove the guts from the PCV.

Dave

FYI... Dave, that won't work on this engine. This is a 1.8, and it doesn't have a PCV valve.

Okay, right now I have a tube running from the oil filler to the air cleaner on my single carb setup. should I do the same thing with duals (about to switch)? just have the blowoff go to one or both carbs?
thanks guys...

If you're going to have a stock heat setup, its not a good idea to vent into the engine bay like the picture shown. All them bad oil vapors you're trying to avoid just get sucked through the engine and pumped into the cab. I'd run it to a real vent tank or rebreather tank and run the air vent for that out of the engine bay, preferably under.

That depends on the filler cap. The 1.8L has a different oil filler assembly because of the L-jet injection. This is a 1.8L filler cap, so it has a very large hole on it to hook to the air intake tube. It also doesn't have a PCV valve or head breather tubes.

If you have a 1.7 or 2.0, you have a different filler cap assembly, and Dave's directions are spot on.

this is what I ordered. How do you suggest I hook it up? one tube coming from the oil filler cap into this box and then vent out the engine tin? seems a little funky...
The guy at CB performance suggested running tubes from the valve covers and then into the air cleaners (drill a hole).
Suggestions?

Find a filler neck with the PCV valve. It will replace the one for the L-Jet. Hook it to the breather box,and use the two tubes provided in the valve covers.