PCV valve for A4 B5 1.8 T AEB motor

[FrenchAudi]

My engine is using some oil, about 1/2 litre per 1000 miles, and the inlet duct is quite oily, so a friend suggested I should check the PCV valve.

According to the Bentley manual this is on the RHS of the engine, on the duct from the air filter to the turbo, and I eventually managed to get it off.

The part number is 034 129 101 A, and it looks like this Ladedruckregelventil Q+, Erstausrüsterqualität MADE IN GERMANY VAICO V10-2504 | eBay , so I ordered a new one.

It is quite oily inside. The mechanism does not seem to move when I blow or suck throgh the connections, but there seems to be more restriction away from the air filter than towards it.

When I Google the part number, it is variously described as a PCV valve, turbocharger boost control valve, and pressure regulator valve.

Can someoe please confirm that this is the correct part, that someone didn't fit the wrong thing, or that maybe VAG used the same part for different applications????

[FrenchAudi]

50 views and no answers?

Seems no-one knows or cares much about the B5 AEB PCV valve setup

Maybe that's why there is so much confusing misinformation out there.

[FrenchAudi]

The new valve arrived, and now that I have determined how they operate, I realise that the old one works correctly.

Gases from the crankcase pass through the valve unrestricted into to the inlet side of the turbo, until the pressure drop across it reaches a fixed value, at which point the main passage is closed, leaving open a small hole of about 5mm diameter. This avoids an excessive flow of crankcase vapour and oil droplets into the engine at larger throttle openings.

There is a another path for crankcase gases, via a non-return valve (NRV) directly into the inlet manifold, but when manifold pressure rises due to the turbo this NRV will close, to avoid pressurising the crankcase.

So positive crankcase ventilation is acheived at low turbo boost into the inlet manifold via the NRV, and at higher turbo boost into the turbo inlet via the so-called "pancake
valve".

PCV valve.JPG