federal

My 1999 Audi TT FWD is overheating and i'm wondering what i need to do to isolate the issue to the thermostat or other..
The Temperature needle climbs to over 110 Deg, the revs climb about 5 points( i think its trying to correct the issue ) and then the fan comes on sending the revs down and the temperature needle back to the standard 90 Deg.
The oil is fine, as is the coolant levels and no leaks. I have changed the coolant temperature sensor though this didnt help.
Could it be the thermostat, pump or anything else ? what the next step to isolating the issue ?

thanks.

EGRoadster

Does it do this all the time or when you are stopped? A 1999 model will probably have over 100K miles on it. If you never changed the radiator, then its efficiency is likely low. And, your AC condenser will do a good job of blocking air at this age.

If the Radiator has never bee changed, consider a 3-row replacement from ECS. While you are at it, clean your condenser.

If your thermostat is blocked, then you'll simply continue to overheat. How old is the water pump? Does it have a metal or a plastic impeller.

Does your radiator fan work? When these cars overheat, the AC fan comes on to help. Start investigating a bit more... Good luck.

Mike Dodd

replace your water pump, exactly the symptoms i had

federal

Changed the thermostat with no luck - still overheating at lights.when the roads are free of traffic There is no overheating issue which i can understand.

Fan is working fine, though i did find a broken air hose that when i replaced, fixed the over reving problem.


before i go and change the pump, is there any basic tests i can run that will confirm the pump is the issue ?

Mike Dodd

I opened my coolant tank and saw two little tiny bits of black plastic. Shine a flashlight in there and look for pencil lead size pieces. That was a dead give away the impeller on my water pump went. Not completely, but enough where it wasn't moving coolant through the engine as efficiently as it should.

You could also have someone rev the engine while you watch the coolant in the tank (cap off) you should see it cycling through there very fast, if its barely moving your water pump impeller is gone.

You could replace the coolant temp sensor with the new "green top" version (I would do that anyway) but can almost garuntee it will be the water pump. Countless other TT owners will back me up on this, the water pump is a high failure item on this model.

GRodriguez

My temp gauge will spike and overheat lights will come on. When I turn the car off then on again it sometimes goes to normal running temp right away. Not sure what causes this. My gas gauge also is not working correctly. Is there a way to check if it's just the cluster? It's a 2002 audi tt 225

killzone

I allways startwith checking the oil for mayonaise forming , then termostat (cheap fix ), nxt is the water pump. Another very good upgrade is Waterless coolant, this replaces the water coolant mixture, pros last the life time of the car and beyond and it never boils, so no over heating . Google it you will be amazed

AudiNut87

why dont u pressure check the system cold. just pump up the res bottle with a brake bleeder tee'd in. pump it to 15 psi and squirt soapy water at all the stoopid plastic coolant connecttions. if 1 if pissing, it wont allow system to pressurize and will do waht you are saying. this is how ive found dozens of coolant leaks. just dont go over 15 psi, otherwise you are risking the heater core. the system should hold that pressure for days. if not you have small leak somewhere. and coolant leaks will spike temp since coolant will turn to steam and superheat unless pressurized