My 2001 A4 Quattro 1.8L Turbo with 102,000 miles overheated last Saturday.
The local dealer did diagnosis and told me the water pump was bad - a $1300 repair (ouch).
I checked the old thermostat at home last nite by holding it in boiling water with a pair of tongs.
The operating range of the thermostat is 87-92 degrees celsius (187-198 fahrenheit).
The thermostat only opened about a 1/4" to 3/16".
Is this the normal opening at operating temps to allow sufficient flow?
Or did the dealer opt for the most expensive repair option?
Firstly sorry about the long delay in replying. No doubt that this has been resolved but I will give an opinion anyway. I agree that the thermostat opening was terribly insufficient. The thermostat should open far further than that. It is obvious that the mechanic did not test the thermostat first as if he did he would surly seen that it was faulty and replaced it first. I hope you went back and complained about this as it seems to happen far to often these days.
Please keep us in mind next time you have a problem and I hope we car answer you question with in days.