By-pass valves

dgraber460 at aol.com dgraber460 at aol.com
Wed Aug 11 14:12:15 PDT 2010


List-et-al;
I have been chasing a full throttle issue on my 3B'd URQ for a few months now. The symptoms have been a flattening and lack of power under full throttle. My boost gauge has always shown full boost at 19-20, and it throws no codes. I started to notice the moaning (not whooshing) noise when off throttle, which I had heard before and found to be an aluminum bypass valve that needed cleaning.
Since it had been running an OEM Bosch plastic valve, I pulled the Forge valve off the S-Car and cleaned it up and installed it. On the drive this AM it seems to have cured the issue. Time will tell if total cure.
The question I have is that I tried to test all 3 valves that I have while messing around last night. I have 2 plastic, and 1 Forge valve. I hooked up a vacuum pump that pulls 14 lb hg to each valve individually and _none_ of them would pull open. Then I used my little Mighty Vac hand pump and the Forge valve would pull open and stay. Neither plastic OEM valve would open with either test. Does this indicate both OEMs are toast?
I assume the vacuum pump did not have a check valve and therefore could not "build" vacuum as the Mighty Vac did, thus letting the valves flutter but not pull open. Sound reasoning?
Also - is there a recommended lubricant that keeps the aluminum valves happy, and functional, or should they remain dry?

Dennis 
Denver


More information about the quattro mailing list