A3 TDI temperature problem help needed


Registered User
Jan 23, 2009
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South Wales
I own a 1999 tdi and I am having some temperature problems with it.

It wont warm up no matter how far I drive or what strain I put the engine under the gauge still stays on 60 and doesnt move, the fan has also never come on.

I have replaced the thermostat with a proper Audi one and sealed it properly etc and it made no difference.

I dont think it is the temperature sender as the water temperature in the expansion bottle is below 60 degrees and you can wiggle your finger in there fine even after a long drive, it almost seems as if the engine is over cooling?

The heaters do warm up a bit and will warm the cab but they are nowhere near as warm as they were on the S3 I owned previously.

Pretty stuck with this and dont know where to go next it still delivers good economy at ~47mpg but I want it fixed!

Any help please?!
Maybe the thermostat is stuck open? I would take the thermostat out and test it to see if it opens to early or just replace it with another new one. Foth sake of a tenner, it's gotta be worth a try.
I dont see the point tbh in buying another £19 thermostat and new coolant when I have just put one in, I removed it just now and replaced it again to make sure it was sealing properly and it made no difference again.

It is the 2nd new thermostat aswell because I bought a non dealer one and tried that before I put the genuine one in and yet again no change!

I have inspected the old thermostat which I removed and that seems to be in good working order aswell.

Another spanner in the mix is I know the temperature gauge does work because I got an airlock while bleeding so it moved up to 80degrees ish on the gauge and then went back down when i gave the pipes a squeeze.