Hi. New to forum but looking forward to your insight.

I have a '98 A4. About 60K miles. Continues to overheat. I'm in Southern California (very hot). Replaced thermostat last year (that was fun). Now have periodic overheating. Flushed the WHOLE coolant system x 3. Antifreeze very clean. No leaks. Top radiator hose gets very hot (so there is flow thru the thermostat). Good belt tension on the waterpump.

The only thing I really have not looked at is the fan system. The electric fan kicks on at startup and stays on for a while. The clutch on the motor fan seems to engage correctly.

Any other suggestions? I'm stumped.
Thanks

 

You could replace the clutch fan with an electric fan kit (EFK). ECStuning.com sells em. Have you replaced your temperature sensor, maybe it is just displaying you are overheating when you really aren't.

 

I actually did replace the sensor about 2 months ago because it was broke and would only work occasionally. Now it seems to work fine. Is there a good way to test the current sensor? I don't want to assume it's broken and let the car get too hot.

 

try this for me. through your climate control you can moniter the engine coolant temp. Follow this guide and see if it matches your indicator.

here

Maybe you have a bad instrument cluster?

 

Does your car detonate at high temps. one more thing you might need to look into is a blown head gasket. this would cauze overheating, because all the pressure is escaping. another thing could be your overflow tank, it also could be leaking pressure. have you tried BAR Leaks Stop leak? this will probably help for a while.

Did you mess with the cooling system before it was overheating? If so, that is the cauze of your problem. The OEM cooling system is built very very well and when you change something you run the risk of messing up. (not getting a good gasket seal, etc.)

anyways get back in touch and maybe we can figure this out together.

 

David_K & Jestnomen,

I did use BAR a while back b/c there was a tiny leak in the radiator. Sealed the leak well. But the sealer ate away and blew out the O-ring on the coolant overflow tank lid. I replaced it with the dealer part (although I admit the thickness of the new ring seems less (but it's not leaking and seems to hold pressure).
The head gasket is my concern... because I know how fun those are to change. That is also why I want to make sure it's not running too hot... because if it's not blown yet... it probably would be soon.

Here was the order of events:
1) system overheated b/c thermostat was stuck
2) replaced and didn't have problems for a year
3) noticed tiny radiator leak
4) Added BAR and replaced faulty temp sensor
5) O-ring blew out on cap
6) Extensively flushed system and installed new O-ring
7) Now no noticable leak, no fluid loss noted, just overheats to about 1-2 past middle mark

And I'm gonna try to run the codes tonight. Will let ya'll know.

Thanks,

 

Hmm did you do the work yousself..if so did you bleed the heater core?

 

ahh i forgot about that. run soapy water around your o-ring, radiator hoses and radiator cap. turn on the car, wait for the pressure to build and see if there \are any leaks. also to help prevent overheating turn on the heater to high. this will allow the water/antifreeze to pass thru another "radiator". this helps to cool my V10 grand cherokee

 

WELL, HERE'S MORE INFO...

First, I did flush out the system according to the Haynes manual (which includes disconnection the heater hose and the upper and lower allen bolts). And I let the coolant cycle for about an hour with the cap off to help any air escape.

Now the codes... first of all Thanks for the codes. I didn't know I could do that.
So I chose option 51c. It never went past 90 degrees C. But the dash needle went up to one bar past middle. And here is something I didn't notice before. As soon as I turned the car off I restarted it and the needle went to dead on middle for about 3 minutes before working its way towards "H". But again, the code temp never went past 90.

So it's either the "new" sensor that was put on or the needle gizmo is bad, right?

The only work I've ever had Audi do is replacing that sensor (actually my wife gave them the go-ahead. I was PO'd b/c they charged $120!!!).

What now? Get my $$$ back?

 

im not so sure youll be able to get your money back but i would get that gauge fixed. glad to hear everything is ok