Just bought my first audi, overheats like hell, but i already love it got it with a blown head gasket but still having problems, ill start from the beginning... bought a 1998 audi a4 1.8t quattro with 124,120 miles... had oil in coolant so it was basically an expensive choco milkshake machine
pulled the head, cleaned **** out of cylinder ect ect, to find what looked like to be a perfect condition head gasket, but for all i know the damage is to small to see idk i haven't done alot of head gaskets, ive only been working on cars for less then a year while going to school for it, and working in the field....
Replaced head gasket and all other gaskets that went with it
cleaned and checked for any damage, checked cylinder bores they all looked really good, unlike some of the other stuff valves didn't look to fantastic maybe been running cheaper fuel, cams ect looked all in pretty good shape, checked block as best i could and couldn't find anything, pretty sure its not my turbo seals because my intake mani, valves cam and hole head wasn't really covered in that sludge ****
Replaced any Orings and what not that needed replaced
Flushed the system as best i could with a hose taped up pretty tight, pressure tight with my garden hose so it flushed my system pretty descent
Bought an oil additive that i ran with oil first time, maybe ran the car for like 5 minutes before i changed oil again and filter this time, put new oil in it again and new coolant in it, drove it around in the city for about 30 mins in the Socal heat with no problems, was about 85 out, stayed at 200 great, but i didnt take it up at all more worried about the head gasket then anything really
Ran it again this time on the freeway and right away the temp shot way up, and the oil light came on, so i took it home immediately, when i popped the hood the coolant in the res was boiling like nuts, and it looked like my oil cooler was steaming like ****, along with the coolant res shooting steam out with insane pressure, the good news is, still no coolant in my oil, or in my cylinder, checked after every drive, its also not shooting out any kinda smoke or anything like that, its just over heating and loosing coolant and oil at the same time pretty quick once its at temp, because its mixing in the coolant and boiling, then steaming like a tea pot out the coolant res haha
once i brought it back i saw a bunch of fresh looking oil in coolant and was pretty concerned, but i figured it was just the coolant getting hot and flushing out alot more of the old oil that the water didn't get, so i decided to take it down to EZ lube and get it flushed with a machine, comes with a free oil change so i said whatever, tested it again with same results, but this time the coolant was completely gone from the coolant res, oil light on ect ect, tomorrow im going to completly rip apart the coolant sytsem and clean / test everything making sure there are no clogs in the system and getting whatever is still in there, also replacing the oil cooler, thermostat, and coolant res, hopfuly that will fix that problem, the last time i ran it it was so pressurized it mushroomed my coolant res and blew the Oring on my cap, so i dont think theres a leak in the coolant system seams pretty capable of holding pressure, but if anyone else knows what it might be i would greatly appreciate it, thanks much for reading!

 

A number of people have reported similar situations, where the oil cooler has failed and caused oil/coolant to mix in some form. It may be worth looking into.
Home Page > ES#257153 Oil Cooler Housing - 028117021BMY
Not sure how others feel about the Meyle brand, but I've been using a number of their parts with great success.

 

thanks man, i will def look into it, that's what i was thinking it was but i really wasnt sure, today im going to do a total tear down of the whole system and ill let you know if i find anything, thanks again

 

Sounds like you have it under control. Radiator might be blocked by sludgey coolant as well.