I have a 98A4 V6. It's been overheating for a while.I've tried everything except taking it to Audi.

Troubleshooting for overheating:
1. Lack of coolant. (Checked - good)
2. Water pump defective. (Replaced)
3. Radiator core or grille blocked. (Flushed and checked)
4. Thermostat faulty. (Checked upper radiator hose - hot)
5. Drivebelt or tensioner broken. (Replaced both myself)
6. Electric fan inoperative. (It doesn't work like it should, but when bypassed it didn't cool the radiator, even when on high)
7. Expansion tank cap not maintaining propper pressure. (Checked)
8. Blown head gasket. (Checked - no coolant in the oil or on the engine)

So far I'vereplaced the thermo switch, water pump, timing belt, timing belt tensioner, coolant temp sensor and electric fan relay.

Someone told me that replacing the coolant temp sensor that goes to the ecm fixed it for them. When I bought the coolant temp sensor from the dealer they didn't mention anything about 2 sensors.I replaced the one that is located by the firewall and the back side of the engine.The sensorusually has a blue or green top to it.Does anyone know aboutthe second sensor (to the ecm)or have any other suggestions? I just hate turning it over to Audi.

 

one of the toughest things i have had to do on my a4 is bleeding a bubble from the coolant lines (which causes overheating.) if you recently changed your fluid, did you properly bleed the system? it might just need burped (sounds like it to me.)

also, you are using proper G12+ coolant, correct?

 

I had the problem originally. The fluid hadn't been changed for a while. Then I drained the coolant when I replaced the timing belt & water pump. It's possible I didn't bleed it properly when I refilled it. I know if you don't bleed properly the heater won't work but I'vehaven't heard of it causing overheating. Are you sure? I just haven't come across the overheating/bubble thing.

Hey, what the hell, I'll bleed it again. It couldn't hurt. Thanks.
And oh yeah, I'm use the G12.

 

maybe i am wrong, sometimes it blurs together. if overheating is the symptom that caused you to change the coolant in the first place, i am out of ideas.

 

maybe i am wrong, sometimes it blurs together.

 

I bled it again and it didn't fix it. I'm pretty sure I did it right. Now what????

 

Is the temperature guage reading high?
Are you getting steam, boiling over?

 

It takes about 10-15 min to overheat. It's a steady climb and the reservoir overflows(steam) when the needle hits the last 2nd to last mark. This is constant. It happens every time.

 

Does the heater produce hot air?

 

Yes,the heaterproduces hot air. That hasn't been a problem.