Put the 87C thermostat back in the car. The car is desgned to operate at 100C in traffic, I would be concerned if it did not get to that temperature.

The fan clutch is designed to be at full lock by about 100-105C. I don't rmember the exact trip points for the electic fans on that car, but I believe it is about 110C coolant temperature or as dictated by refrigerant pressure.

It is normal to se 85-95 on the open highway and a hair over 100 in traffic.

The reason that the BMW coolant temp gauge does not move is that it is programmed to sit in the middle no matter what the temperature unless the car is severely overheating. For example, Mercedes wanted people to stop worrying about the normal operation of an inernal combustion engine in traffic, so they removed the real coolant temp gauge and put a dummy one in the newer cars. On the W202 C class, the gauge operates normally until 95C and then the gauge stays on 95C as long as the engine temp is anywhere between 95C-115C. Only above 115C does the needle then rapidly race to the red. Thus problem solved with the newer cars.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record