[T3] Fw: '72 FI won't idle down

[bobsnotch at aol.com]

 Dave, the idea that Ray suggests is that you gut the PCV valve, and the 3mm hole becomes the valve. The main thought is that the 3mm hole becomes a constant air leak that you can tune around. This is because there's no one rebuilding or offering rebuild parts for the PCV system. He uses a chunk of plastic w/a hole inserted in the hose from what's left of the valve, going to the IAD. His thought was the valve opening and closing whenever it wanted was working against the smooth idle, causing it to become choppy. As for the 3mm size, he worked on various sized holes until he found one that worked right (over years of testing). I hope this helps.Bob 65 Notch w/factory sunroof
   ----- Forwarded Message ----- From: David <rdavid at rochester.rr.com>To: "type3 at vwtype3.org" <type3 at vwtype3.org>Sent: Thursday, June 11, 2026 at 12:56:00 PM EDTSubject: [T3] '72 FI won't idle down  
 After further review - I reread Keiths response and realized I
misinterpreted what he wrote.

[[[One thing I had to

do was put a restriction in the line to the crankcase breather, something
Ray Greenwood suggested, about 3mm, that seemed to work and allowed it to
breath but kept idle within range.]]]

I believe I now understand that the added restriction is between the PCV
valve and the IAD, which would in fact reduce the amount of air that passes
between these 2 components - while still allowing enough air for the PCV
system to function normally. Less air into the IAD = lower idle speed.

The part I still don't understand is the 3mm part. What & how creates the
3mm reduction?

Dave Pallo

'72 Square ~ Elwood

Fairport, New York

 

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