maybe a headgasket? or mixed coolant?
 

I just bought a 1998 A4 1.8T.. the PO said he was told it needed a headgasket.. the coolant is contaminated with something, but I just changed the oil and it had no coolant in it.. the car had this brown junk and water in the cooling system.. I towed it home. I have attached photos of the coolant reservoir and oil before I changed it.. is it a headgasket or do i have another problem? I also have a small coolant leak by where the coolant temp sensor mounts, is that common?

https://www.audiforums.com/forum/att...1&d=1321122673
https://www.audiforums.com/forum/att...1&d=1321122673

look into the oil cooler. I had this same problem.

Oil doesn't look too bad. Could be oil cooler or head gasket but it looks to me like someone mixed coolant. Your coolant should be bright pink, but if you mix regular green coolant with G12 (the pink stuff) it turns into gunk much the consistency of the gunk in your pic. That would also explain why there's no coolant in your oil, which would be the case if your oil cooler took a shit.

It's your oil cooler. Your going to need to flush out your coolant system and get a new coolant reservoir too or you will have overheating problems like I had.

CCA4 looks to be dead on, from what I've seen in these cars. We did a block flush on one car that had mixed coolant and it looked just like that - milkshake crap on the cap and Bangladesh river water in the reservoir. Flush the entire system until you get nothing but clear water out of the radiator drain and the block drain, and then refill with G12. Do it soon too, before the stuff gels up and really ruins you.

Well they already said what I think... Someone mixed shitty coolant with the goodstuff and bam SCIENCE happens and gunks up your car!

picked up a new oil cooler and the coolant flange on the back of the head. hope to have it fixed this week, but with a 71 hour week, time is just not there..I think I did good for a 600 dollar car.. body is strait and the interior needs to be cleaned some, but its in nice shape...

Even if you spend $2k in parts and repairs, you still got your money's worth for $600. Good luck! Post back and let us know if the oil cooler fixes it. I still think its mixed coolant but no body listens to me around here anyway :p

oil cooler and flange are in. no leaks, now I get to clean out the cooling system

Did you get a new reservoir too? I tried cleaning that crap out before using engine degreaser and high pressure water and there was still some crap stuck in the narrow channels in there. That would make the car overheat believe it or not until I put in a new one.