Do you have white smoke coming from yoru exhaust? Any coolant in your oil? Check your oil.
Is it just the water temperature rising? Could be your thermostat, water pump, or a loose hose.
A water pump is a common failure on our e36 cars. The fatcory water pump has a plastic impellor blade which breaks and fails to perform any more. If you havent already, you should check this out and upgrade to a metal impellor water pump.
1995 BMW M3 Turbo - Dakar/Black