I've bought a used VW/Audi recirv valve, part number 034 145 710 C which I believe is reasonably commonly used with G40 turbo conversions. It's the same as in the photo below pinched from an American Audi site.
(http://www.s4biturbo.com/files/bosch_side.jpg)
The valve doesn't appear to operate as I would expect, but would like to make sure I'm not misunderstanding the valve before condemning it...
If I suck on the vacuum line then it will suck air through the 'pressurized air dump in'. When connecting the valve to a vacuum line on my engine it won't open, but when the valve is gently pushed open through 'pressurized air dump out' the vacuum will hold the valve open.
I suspect the diaphram between the vacuum side and the boost side of the valve is shot, but looking for confirmation please chaps. Cheers.
Yup, fooked seal
(http://i734.photobucket.com/albums/ww343/cheys03/IMG_3910.jpg)
(http://i734.photobucket.com/albums/ww343/cheys03/IMG_3909.jpg)
Looks like it's torn (no I've not sawn into it!) where it is folded and sealed under the cap. Damn nuisance.
these dump valves are crap, they don't last long as the rubber easily splits, i have about 5 of them in the boot of the car as spares, they don't last long with 22psi of boosts!
Duly noted! :D
yeah I had one pop on me half way through a track day. Ran the rest of the day with a screwdriver handle shoved into the dump valve hole :D
Wont buy one of those then! Lol
My opinion - GReddy Type S insted of the Bosch one - good recirc dump valve, hard to appear damage on it ;)
(http://www.autopassion.co.nz/site/images/Greddy%20TypeS%20BOV.jpg)
Negatives - may be too big valve diameter (35mm insted of the 24mm in Bosch one) and the price of it!
Tial make some nice ones too. Although I'm currently using a right chavvy one that a mate found in his shed, I think it was used on an escort rs turbo, it's anodised bright blue and makes a right racket but it's not blown up yet. I might save some pennies for a nice Tial one though!