Over heating.....help

[nicko86]

Hi guys looking for some advice or my 8l s3, she was overheating past the 90 so my first thought was its a possible head gasket. I have no gunge, loss of coolant etc so wasnt convinced, just had a head gasket test which came back fine. is this a thermostat issue or possibly something to do with the fans? anyone familiar with this? water pump is working as should also.

any advice welcome cheers audi fans!

 

[lol4fun]

Temp should get to 90 and stay there then as the thermostat opens at about 90 the radiator gets hot then when the radiator is at 90 or just over the fan will cut in

 

[nicko86]

whilst doing the head gasket test, the pipe connected to the thermostat, radiator was freezing cold so it would suggest the thermostat iisnt opening therefore the fans dont get to 90 because they assume the car is cold if that makes sense?

 

[lol4fun]

Yup, the thermostat is stuck, I would replace it asap, and might as well replace the coolant while your at it

 

[nicko86]

coolio, fairly sure thats the problemo then, save me some ££££'s! thanks lol4fun! nice to have some confirmation.

 

[lol4fun]

There is a small possibility of an air lock but if you've not done anything to the cooling system and its not run dry then that's unlikely plus they are pretty good at bleeding themselves, the small pipe to the top of the headder tank should get hot pretty quick even with the thermostat stuck shut as that's the self bleed pipe.

 

[s3mad_dude]

If that's not the problem, the next thing to check is the water pump. If you're on your original item the impellers often fail. The part has been revised since.

 

[CabbageGT]

What are the heater matrix like on the A3/S3? I've had many cars overheat due to blocked heater matrix. Easy way to tell is to use the heaters when the car is hot. They would be cold if there is a fault here

If your replacing your thermostat, it wouldn't hurt to check that the old unit definitely doesn't operate by putting it in a pan of boiling water.

I'm guessing the car is overheating when in traffic? Or all the Time?

 

[nicko86]

once up to temp the car overheats, heatings working fine still thank god brrr