2.5 TDI A8 D2 Overheating

[shawns]

Hey guys bought my first audi a8 today 2.5 tdi done 223.000km

the guy i bought it from tricked me he said the car was absolutely fine and no water/coolant/oil consumption.

He insisted for a short test drive because he was in a rush so i took it for a test drive it drove nicely some bulb warning lights came on other than that everything was fine. Except the heater was just blowing out cold air and wouldnt blow hot air (it was on full blast on heat) the guy said it will start working when i drive it a little bit.

I had a journey of 150km to home and after 20min of driving and temp gauge at 90* it was still blowing cold air.

so i pushed the car a little bit and made it go upto 140km/h suddenly it was blowing hot air and i got very happy.

5min after that the temp gauge was still showing 90*ish but on the computer lcd i got a warning for high temperature but gauge was still showing 90.

I popped the bonnet and opened up the coolant resevoir , and there was alot of pressure built up it was really boiling but car performed fine. I topped up the coolant and after 10min the same happened and i had to fillup around 0,5l coolant.

So on calm low rpm driving there is no overheating but only cold air from the vents. Even sometimes on hard driving it doesnt blow hot air. The air gets hot around 5min before the overheating warning sign show up on the computer.

Overheating warning comes even with full coolant level


Can you guys please help me ? Locate the problem......i feel so scammed

 

[adamss24]

Cracked head...what is the engine code ?

 

[shawns]

Cracked head...what is the engine code ?

It's the AFB engine

 

[adamss24]

It's a bit unusual, i would check the water pump first, the impellers are plastic and detach off the shaft hence the engine overheating. Either way, it will cost you money to fix, where about's are you based ?

 

[shawns]

It's a bit unusual, i would check the water pump first, the impellers are plastic and detach off the shaft hence the engine overheating. Either way, it will cost you money to fix, where about's are you based ?

Im based in norway. got it checked by a mechanic today he meant it was the head gasket as there was pressure going back to the coolant resevoir , but after calling a collegue and asking him to check it , his collague said it can be the water pump as the top radiator hose had no pressure when the car was cold and there was no mixture of oil/exhaust in the coolant.

I personally think its a partially stuck/bad termostate and water pump is not working fully.. Ive decided to do a full cambelt , waterpump , termostate replacement by the mechanics. But im kinda worried that if i spend all that money on those things and at the end of the day the culprit is a bad HG or cracked head like you were saying

 

[shawns]

Guys no response???

Got the water pump removed and it was looking really good no broken impellers etc. but there was alot of zinc built up inside the wp maybe it has been run on water and coolant hasnt been changed. Will put everything back together today lets see what happens

 

[adamss24]

Every thermostat i have replaced on a v6 tdi was stuck wide open and the car would not overheat at all, i would check properly for leaks and be prepared to pull the heads. Head gaskets on diesel cars do not always mix water with oil, they rather pressurize the cooling system and the water cannot flow anymore... Blocks are cast iron and i never seen one cracked, i would look for heads from a later BDG/BAU/BDH engine with cam rollers and swap them over- you make the engine bullet proof that way !