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David-VAG, ASE Certified Technician
Category: Audi
Satisfied Customers: 844
Experience:  I've been working within the Audi group for over 10 years diagnosing and repairing them
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Hi I have just got an audi A8, 4.2 petrol. Year 2000 Car

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I have just got an audi A8, 4.2 petrol. Year 2000

Car is over heating and the oil is getting in to the coolant tank. Coolant will then bubble up and spits out a mushroom soup mixture.

Do you think head gasket has gone, or possibly oil cooler.

If head gasket, can i work out which head has gone.



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Customer: replied 3 years ago.
Yes still waiting
Hello and welcome to just answer

If oil is getting into the coolant I would first be looking in to the oil cooler rather than head gaskets. You can normally check the oil cooler yourself with a fairly simple test.

The best way that I have found to test these is to remove the coolant pipes from the oil cooler and then join the two rubber pipes together so you don't leak coolant every where. Then run the engine and keep you eye on the oil cooler connections for the coolant pipes. If the cooler had failed you will eventually see oil come out of these pipes, as under good conditions nothing should come out except any water that may be trapped inside.

If there is a head gasket failure I don't believe that you will be able to find out which side is at fault and to be honest there isn't much more work involved in doing both sides any way. I would also recommend that you check the water pump is functioning correctly.

I hope this helps and if I can help further please feel free to ask

David-VAG, ASE Certified Technician
Category: Audi
Satisfied Customers: 844
Experience: I've been working within the Audi group for over 10 years diagnosing and repairing them
David-VAG and other Audi Specialists are ready to help you
Customer: replied 3 years ago.

Waiited almost a week for a reply, so have since do e a few jobs to it.

Looking at tye thick sludge we drained out, we actually wondered if someone could hqve been stupid enough to have filled the coolan system with oil. Proper thick, beige colour.
Don't think the head is at fault as temperature seems ok. Compression is almost equal on all eight cylinders too.

I will check the oil cooler today after a few more coolant flushes.
Any other suggestions would be appreciated.


Another thought I have had would be a possible oil cooler for the Automatic Gearbox if you have on installed as this runs down the side of the radiator.

Please let me know how you get on with this and if you need further help.


Customer: replied 3 years ago.

Hi dave.


Oil is cooler is out now. Was a tough job as it is buried right inside the oil filter housing.


No hoses connected, just o rings.


Is there any way of testing this type of unit, before I go and purchase a new one.





Hi Pat

I have never heard of any fully successful way of testing oil coolers. I have previously sent them away for them to get the all clear and then fitted them back on to find that they are faulty. So unfortunately I can't suggest a good way to test it that would give you a 100% correct test result.