How a leaking cam seal can kill your AAN/ABY/ADU

[UrS4boy]

The cam seal (PN 068203085E) sits virtually directly above the G40 Cam Position Sensor, i.e. one of the electronic devices that the ECU needs a good signal from before it will send the right signals to the injectors and coils to start the engine. If the seal is worn and leaking oil, it could get on the G40 cam sensor and mess up the signal that it would other wise be creating for the ECU to read. The photo below shows a G40 cam sensor that has been saturated with oil leaking from a neglected cam seal. Easy fix. Replace the seal and probably just degrease the cam sensor and put it back into service.

Something (else) to check if you are having starting or running problems with your AAN/ABY/ADU engine.

G40 Cam Sensor info including replacement procedures, if need be:

http://forums.quattroworld.com/s4s6/msgs/22580.phtml

Cam seal (a good,non-leaker):



A G40 saturated in oil from a leaking cam seal:

[elaw]

Um... how is oil going to "mess up" (functionally, not cosmetically) a cam sensor?

The sensor detects the window in the shutter wheel via a magnetic field. The only way I can see oil affecting that is if it's carrying magnetic particles - in which case you've probably got bigger problems than a malfunctioning cam sensor!

[UrS4boy]

Um... how is oil going to "mess up" (functionally, not cosmetically) a cam sensor? The sensor detects the window in the shutter wheel via a magnetic field. The only way I can see oil affecting that is if it's carrying magnetic particles - in which case you've probably got bigger problems than a malfunctioning cam sensor!

Don't know the exact mechanism but it resulted in running and starting issues. Maybe the oil ate the wiring/insulation and shorted stuff out. Don't know. The engine stopped working as a result.

[elaw]

Wow! And removing the oil fixed it? I'd have thought damage like that would be permanent.

[UrS4boy]

Wow! And removing the oil fixed it? I'd have thought damage like that would be permanent.

In his case, he had to replace the cam seal *and* the G40 cam sensor. My degreasing suggestion would be something that one might try before replacing the cam sensor. However, since they are under $20 from EFI Express, you would probably not take the chance once you have it exposed to do the cam seal.