C4 UrS - "Secrets" hidden behind the front fenders.

[UrS4boy]

Base photos courtesy of Gary A. (aka Helmut/Reinheitsgebot)

Left fender


Right fender

[Majorcina]

I dont know why but i dont have on my right fender "emissions bleeder valve",and on my other urs4 i have.Can u tell me what is that exacly?

[UrS4boy]

I dont know why but i dont have on my right fender "emissions bleeder valve",and on my other urs4 i have.Can u tell me what is that exacly?

The bleeder valve is a safety feature check valve that only allows vapours from the fuel tank to be drawn into the evaporative emissions canister based on engine vacuum via the N80 evaporative emissions control valve. It prevents intake boost pressure from getting back through the system to the emissions canister and fuel tank.

N80 Evaporative Emissions Frequency Control Valve and Canister info:

http://forums.quattroworld.com/s4s6/msgs/21014.phtml

Item 18 here:

[Majorcina]

I have a hose which go directly to the canister,what can go wrong if i dont have it?

[UrS4boy]

I have a hose which go directly to the canister,what can go wrong if i dont have it?

The Evaporative emissions canister is connected to the intake manifold via the rubber "T" just below the AAN intake. If the N80 fails to close under boost pressure, with out that bleeder valve, it is possible that boost pressure would go through the N80, through the evaporative emissions canister and into the fuel tank. Sounds like a recipe for potential disaster to me.

[Zoig]

The seal piece 4A0 821 197 C is allegedly the reason why many of the UrS6 and possibly A6 front fenders start to rot from inside out. They trap moisture under the edge and over the years due to vibration it eats trough to the bare steel. Picture from the Left side seems to have some rust residue just ontop of the seal piece. Dave do you know if that fender had any rust in there when it was taken off?

[Majorcina]

Dave,do u know how much that stuff can cost?I am 100% sure i cant find it in my country