So, a very short backstory. My father own an A3 from 2003 and it sometimes overheats. I'm writing this because his birthday is about to come and I want to help him with the car. The problem is that the car overheats to about 110-120 fast but not all the times. It does like to do that in the morning sometimes. But... it only does that sometimes. Like the car can go 50km and be straight on 90 three days in a row and on the forth day it overheats. Everything has been changed, like the sensors, thermostat, water pump with new parts. He went to several mechanics and they could not find something wrong. Also.... my dad discovered that if you hit a pothole or the dash sometimes the temperature goes back to 90 or go from 90 to 110. What can be the cause of this. Thank you in advance!

 

Do you have any oil leakage or coolant leakage? Could be that one/more gaskets are leaking and causing your car to overheat. You can also see if there is any burn in your coolant or if you unscrew the top of the engine (where you pour oil) and see if there is any white foam. It could be _one_ of the reasons for overheating.