I have recently replaced the waterpump, stat, stat housing, rad, coolant and viscous fan on my E34.
The overheating problem I am having is strange. I haven't noticed any coolant loss. I could do 100 miles in the car one day it will be fine and the temp stays in the centre. Sometimes it will start to rise quickly (I haven't let it go into the red) and if I switch the car off and on the overheating stops.
Its happened a good 5/6 times.
Once it started to overheat on the motorway I pulled into the hard shoulder and switched the car off and on it didn't overheat again for the rest of the journey.
What could be causing this? I'm lost on this one.