i was driving on the highway the other day when my carstarted overheating (2002 A4 1.8t quattro, 77k miles) I pulled over, let it cool down and drove off again. Itkept overheating so Idid this repeatedly until i was able to get to a gas station. I noticed that the colant was low so i added a bit of water, i turned on the car and let it idle and the temp was fine but when i started driving the temp gauge shot back up!

-the car doesnt overheat when its idling
-i can hear the water bubling inside after it overheats
-upper radiatior hose is hot!!! not sure about the lower hose
-i cranked the heater up all the way but there was no heat

any ideas as to what might be the problem?? the first thing that came to mind was the thermostat so im gonna try that first, any tips on changing that as well???

Ive tried looking all over the forum for similar problems but i havent seen anything! appreciate any ideas, thanks guys

 

the fist thing you have to consider is if the coolant fans cut in but you can hear bubbling that indicates air in the system or head gasket or could just be the coolantfans are not working which means you have a chance but slim

 

Could need bleeding. Remove the 3 screw that hold the G-12
reservoir. With the engine running hold the reservoir up and add
G-12 antifreeze.

 

so would it be that i just got air in the system??? what could have cost that!!!

 

sorry, what could have CAUSED that?? my bad

 

Sounds like a bad thermo to me.

At idle, it may take a lot longer to heat up, if it even overheats at all. But drive it and the stuck thermo becomes apparant right away.

Its not too hard to change, and cheap, so if there are no other obvious signs of leakage, I would start there.

The air bleed could be a cuase also, but if its been fine for a while, and you haven't changed coolant or done anything to the system, that problem should not just "pop up" out of no where.

 

I heard that if you disconnect a coolant hose on a cold start up that you should be able to tell if the water pump went bad becuase it will not cycle water through and no coolant will come out of the hose??? i guess it kind of makes sense but would it work???

 

Most likely a your water pump is going or your thermostat is stuck shut.

 

its an 2002 so i found out it has an electric thermostat which apperantly arent cheap!!! anyone know if its a common problem???