Hi all, this is my first post so be gentle if its in the wrong area : ) I'm after some advice. I recently bought a 52 plate 225 TT in Mauritius blue. I've had several problems with it, biggest one being the stripped insert in the turbo (manifold side) but that's another story-now fixed. Next problem is the overheating. Temp gauge on dashpod shows around 80, then climbs quickly up to 130 and throws up the high temp warning on the centre display. Give it a minute or two then it drops all the way back to below 80, then settles just over 90. This happens whether in traffic or sitting at 70, and has even done it 1st thing in the morning stone cold engine and within 10 secs of driving its off the scale which is impossible even with no coolant at all! Doing the 49c trick and the air con module mirrors exactly what the dash needle says, up and down. Ive now replaced the thermostat twice, coolent temp sensor twice and just done timing belt and water pump, impeller was fine on old pump. Car runs fine otherwise and i'm losing the will to live. Tomorrow i'm going to fit an aftermarket temp sensor and gauge. My friends an Audi tech and suggested the dashpod, something about the can bus being shared with the climate control, he lost me lol Sorry for massive post!

 

When you turn the AC on, do the fans kick on? Also, with the engine running, see if there is fluid in your upper and lower radiator hoses. If not, your water pump might be bad. If you can confirm that the car isnt overheating, but showing on the gague, swap out your temp sensor.

 

Hi warranty thanks for your reply. I can confirm fluid in both the upper and lower hoses, and the both the fans cut in when they should. As I said I've just replaced the water pump yesterday and both thermostat and coolant temp sensor twice over the last fortnight no change. I just disconnected the sensor and took it for a quick run, randomly the gauge and 49c both managed to reach 50 degrees then settled back to 30 after a minute. I'm no expert but if the sensors not even connected what business does the gauges have in moving?? lol Fortunately I have plenty hair left for pulling out

 

stock water pumps have plastic impellers. they move plenty of coolant at idle, but will freewheel on the propeller shaft at higher rpms.After many heat/cool cycles, the impeller weakens and freewheels on the impeller shaft. My advice, replace your water pump with one that has a steel impeller. That solved my overheating issues. Good Luck!