Hi all, thanks for this forum I have gain lots of knowledge about my car and its problems. I'm a long time reader but 1st time poster.
I have a 2002 1.8t with 90,000 miles on it. I have it serviced for new Timing belt and water pump (metal impeller, according to the shop) 3 months ago at this shop. The overheating problems never went away. The problem is that it overheating at heavy traffic or idle after a while or after heavily drive, but it cools off quickly when I rev up the engine a little bit, or after getting out of traffic again.
I have another shop diagnosed, they first told me the cooling system is leaking and may trapped air inside so they did replace thermostat, coolant housing assembly, flange seal, pipe sealing o-ring. they re-test and turn out there is no coolant flow and suggest that is it the water pump that fail and ask me to go back to the original shop for the Water Pump warranty. Additionally, they flow test radiator and its fine.
I did return the car back to the original shop and they tested and said the heater core is clogged with debris and that would cause the overheating. They asked me to replace the whole heater core that would cost $1500. But I know for the fact that I have heating in the car and it is hot!
Is there any other reason than what have been replaced or tested (thermostat, radiator, air trap, new coolant)? I think it could be the aux cooling fan since its never turn on when overheating, only when AC is turn on, is it supposed to work this way? I am very sick to my stomache now. spent too much on this car and hopelessly the problems went away but it's not. please give me any advice if you can.