Head Gasket or Oil Cooler ?

[Adjani]

Found the dreaded dirty brown gunk in my expansion bottle, Audi mechanic said it could be the oil cooler rather than head gasket and he could tell by looking, how? What checks could be done the layman (me) to discover which bit is broke.

X Reg A4, 2.4SE, also got white smoke from the dipstick tube oil is clean, hope this is enough info

[adamss24]

Hi, looks like a blown gasket mate ! If it was the oil cooler, you will have oil inside the header tank, by the way is the car overheating ? I would go with the oil cooler first as its easy to swap then pull the head and fit a new water pump/termostat if the car is overheating.

[sean prasad]

Hi adjani,

Sounds to me like your head gaskets have had it, as there is brown gunk in the expansion tank. It is rare that the oil coolers split on the 2.4 SE engines but i have seen my fare share of head gaskets!
If i was you i would check for possible white smoke from exhaust when cold and hard starting when left overnight as these are the most common signs of a blown head gasket.

[bbmkayr]

Having just experienced the same problem, but on a 1.9tdi (AFN) Passat with its Oil Cooler on the Oil Filter Base. The best way to check the Oil Cooler is to bypass the water jacket by joining both water hoses with a piece of suitable pipe and monitor the oil cooler connections for an oil leak. It took almost an hour of constant running for the oil to show up at the lower of the two pipe connections, once I had cleaned out the cooling system - using a couple of capfuls of biological washing powder and a steam cleaner. The washing powder made a good job of cleaning out the expansion tank too. Only remained then to change the Cooler, flush out the Cooling system, again, and replenish the Antifreeze mix.

The original Coolant was a dark grey due to the mixing / emulsification effect of the two liquids - great relief after contemplating a head gasket change, even though the car has done 193,000 miles. To be fair I have not had a failed Passat /Golf TDI head gasket yet nor has any one else I know (yet).