I have a 1981 300D with 196k. the car runs great. But as the weather is getting warmer I noticed that my engine temp is going up. This is normal. However at idle or in heavy traffic it is running much hotter than normal. Last fall I was told the fan clutch is bad. How can i verify this? I am thinking this could be the problem since the engine only gets hot at low speeds or idle. Also at what temp should the electric fan turn on? I replaced all the hoses and coolant last year as preventive maintenance and notice that it seemed to have good water flow thru the radiator. Can a bad water pump cause this? Any help is appreciated.