Blacky/white gunge in header tank

[yellowbus]

Running a 1.9 TDi from an Audi 80 and recently been having what feels like fuel surge so assuming the filter has sucked up some "pooh" am going to change it.

Doing the usual checks and the header tank behind number plate is empty and the main header tank is filled with a blacky-grey foam like gunge, any ideas?

Its not overheating- god knows how not as it can't be healthy.

Cheers,
Kieron

[lhd]

Check oil cooler..... (oil filter screws into it)
They corrode and then high pressure oil gets into the cooling system, if so replace and properly flush the cooling system.
Otherwise could be the head gasket.
Rob.

[geordie skydiver]

Same thing happened on my Audi 80, it was the oil cooler.

Replace it, and oil/coolant and keep an eye on it.