[frogers911]

I am in need of some help troubleshooting an overheating issue with my 98 M3.

First off some history. I have had the car for ~3 years and 30k+ miles, it is currently sitting at 213k miles. Last complete cooling system overhaul was around 165k, when a the top end was also rebuilt. I have had no engine issues.

I use a scan gauge to monitor coolant temp and typical highway temps are around 196-198 and stay around the same when stopped (never over 202-204). A month or so ago while in carpool to drop the kid off the temp starting going up and hit 220 before I was able to get out of line an moving to drop the temp.

Fan clutch maybe or air in system? Bleed it and put in new fan clutch, same problem.

I was due for a cooling system swap anyways (every 60k) so I went ahead and ordered everything. I replaced the following:
Radiator
Water Pump
Thermostat & Housing
Reservoir and sensors
All hoses, tensioners & belts

I have bleed the system once so far but I am still getting the temperature increase when the car is not moving. My main concern is that the upper radiator hose is easy to squeeze once the car is at temperature, I thought it should fill with fluid once the thermostat kicks in and be stiffer? Is that correct?

I am going to bleed it again and check the fan clutch this weekend but figured I'd seek some advice since I don't have time to work on it during the week.

Some other notes from the swap:
-Coolant came out clean
-There was some white build up at the thermostat housing but I don;t think this was electrolysis damage (Picture attached)?
- The engine block drain plug had some residue and maybe rust on it, the hole in the engine block also showed some corrosion. There was some corrosion inside also, I scrapped out what I could but didn't see a way of cleaning it.


Any help is greatly appreciated.