Just bought this 93 SE sedan 245k miles for a song and I guess I know why now. But its ok, I am fine with some engine work at this price. Im just not convinced its a HG issue. Car originally sold bc oil leaking in a steady stream when engine ran. I replaced both oil pressure switch/sender and the oil cooler O-ring. No more leaking oil. But then I checked the radiator for coolant before taking it on a short drive and I find brown oily coolant, and the pics below show the accumulation of what looks like sand? in the reservoir. Is this aggregate parts of the engine rusting away all this time and depositing into the reservoir? Is this a common feature of a HG failure - the "sand" in the coolant? I mean, could be a kid dumped a handful of sand or something in the reservoir I guess. Any chance the oil cooler (A6 engine) has been mixing oil and coolant? Or the lower part of the radiator doing the same? Havent driven the car enough to have any sense of overheating or temperature issues yet. Thanks for your thoughts!

 

IDK anything about the A6, but could that sand just be a form of stop leak? I know they have the silver stuff, they also have one that turns into a wax as well as one that solidifies in a dark brown material (Bar;s brand).

 

Yep, that could be some head gasket leak stuff. It typically has a light chocolate, sandy metallic look when its new in the coolant, but can solidify if too much is used. Looks like the previous owners just dumped that crap in by the caseload.

Does the brown fluid itself have any metallic look to it when viewed from different lighting angles? If it does then they definitely used some head gasket stop leak material as a fix.