Hi there, I own an Audi A4 b7 2.0L TDI, head gasket went a month or so ago, got it fixed, a month later, I’ve noticed that the car has a black sludge in the coolant tank, as well as this, it’s been starting/ idling about 200/ 300 rpm higher than normal (900 rpm), this usually occurs at the same time that I hear a rapid fire knocking coming from under the dash of the car.
i have googled it and forums suggest it’s a oil cooler leak, and I need to get that fixed.
From my info, does anyone have any thoughts about what might be going on with the car?
just to add. The engine
