meternerd

I found the hose on the bottom of this thing disconnected...looks like for a long time. Re-connected it and performace seems MUCH better. What is it, and would a disconnected hose cause lowered performance and occasional Codes? Looked in my Bentley's manual and nothing found. Connects to side of Y-pipe.

tester123

Looks like the PCV (Positive Crank Ventilation) valve. Google about its function. If disconnected, could throw off some things.

Nazman39

It a pressure limiting valve. Look on page 30 of the pdf at this link: https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.ibiblio.org/tkan/audi/2.7Biturbo-SelfStudy.pdf&ved=0ahUKEwjl886MpbTSAhVEVWMKHWBNAjY QFggaMAA&usg=AFQjCNGYCNugcEaCZeVgs6qB1nULt_cFCw&si g2=TCvGJfGo9_ge1D1Uh14f2A
Cheers,
nazman39

raj99

This link seems to work better: https://www.ibiblio.org/tkan/audi/2....-SelfStudy.pdf

jcman

Oh the old CVV "Crankcase Vent Valve" It's also known as the Honking Hockey Puck when it goes bad.

tester123

I had a thread long time ago about this making duck calls from my engine (thanks Amazon for such an original part). People knew when I was in town!

OEM part's silence is a golden goose.

jcman

Funny! I seem to remember that one and I've also added a couple of 2 cent comments myself on the subject over the past years.

meternerd

Wow....great source. I really appreciate the replies. First (and probably only) European car I've worked on, not counting the MGB. Everything on it is a PITA to get to. I'm still loving the car, though. Did a timing belt once at 90K miles. Brakes are easy to do. Torn CV boot, but replacement axle was easy, too. Struts, easy. Cracked aux coolant pump BIG PITA. Front oxygen sensors, not too bad...coolant temp sensor, easy...158K now and all is well. Too dang old to tackle anything big again....next ride will probably be a wheelchair....

georgeb944

If you liked that self study course, here is a list of more than you would ever want to know...

Various VW & Audi Self-Study Programs - SSP