Mk2 Audi TT - Correct Running Temp?

[Seeker UK]

One for the TT owners.

Mrs Seeker has a 2.0l FWD Mk2 TT with S-Tronic box.

On an 80 mile run last night, the temp gauge never rose above 70 C and this has been the case for a while. We queried this at le last service and we were told it was OK. It doesn't seemn right to me, given the OBC was showing an average fuel consumption of 34 and the 80 miles was all M-Way and A-Road. IME that seems like its running too cold and the car is p*ssing fuel into the pots, thinking it's at startup.

Sounds like a new thermostat is needed. Thoughts?

Thanks as ever, PH'ers.

[mercedeslimos]

Common problem on all 2.0 TFSIs, thermostat sticks open. Should be running at 90 or thereabouts, and higher under load. Stat is under the alternator but DIYable if needs be. DSGs have a second one over the top of the box too.

[Seeker UK]

mercedeslimos said:

Common problem on all 2.0 TFSIs, thermostat sticks open. Should be running at 90 or thereabouts, and higher under load. Stat is under the alternator but DIYable if needs be. DSGs have a second one over the top of the box too.

Thank you.

Why the second thermostat near the DSG?

[mercedeslimos]

Seeker UK said:

mercedeslimos said:

Common problem on all 2.0 TFSIs, thermostat sticks open. Should be running at 90 or thereabouts, and higher under load. The stat is under the alternator but DIYable if needs be. DSGs have a second one over the top of the box too.

Thank you.

Why the second thermostat near the DSG?

I'd hazard a guess about controlling the coolant flow to the DSG oil cooler, as it's an oil warmer when the oil is cold and dissipates heat to the coolant when it's hot. The DSG stat is an in-line one, whereas the main one is a stat and housing (non-separable) with a sensor on IIRC.

Not a TFSI problem per se, 9/10 TDIs I've owned have needed a stat, my single TFSI has needed it, as have both mates with vRS or GTIs. Just seems to be one of those things. The only downside on the TFSI is it's a harder job to do, and a more expensive part as the housing isn't separate so is thrown away with the busted stat, unfortunately.

[Seeker UK]

mercedeslimos said:

The only downside on the TFSI is it's a harder job to do, and a more expensive part as the housing isn't separate so is thrown away with the busted stat, unfortunately.

Having had a 2.5 V6 TDI which required removing the front of the car and all the belts to replace the thermostat, it sounds a lot simpler to do.

That said, we have a good indy nearby we can get to do it.

Cheers,