My A4 overheats very fast, I can't drive it past 10km without it overheating like crazy. When I start up the car and have it idle for about 12 minutes, it starts overheating. Any suggestions on what to do?

 

not nearly enough information, but with what you have given id say your waterpump is bad.

 

does the gauge say it's overheating or did you measure the coolant temp with a thermometer?

 

The gauge says its overheating and the coolant starts to bubble over

 

it could be a bad thermostat. basically the thermostat keeps the coolant inside the engine to warm up and when coolant reaches a certain temperature, the thermostat automatically opens to circulate the coolant.

if you can, take the car apart. it's been a while but iirc the thermostat is behind the waterpump on the 2.8 30V motor. you'll be able to tell instantly if the water pump is bad. you can put the thermostat in boiling water to see if it opens. if you have a 1.8t, i believe the water pump is driven by a separate belt than other accessories on the engine. see if you still have that belt on there lol

 

Any luck... hope its just water pump with retarded plastic impeller spinning on brass bushing. Or sticky stat, kinda doubt. Head gasket? Check for exhaust gas from coolant header tank.