Cooling problems due to a stuck thermostat or low coolant should not improve with engine/road speed. I suspect the water pump. If the pump is badly worn (either not moving coolant or allowing it to backflow within the pump) it will pump badly but might improve as engine speed rises.

At the temperatures and engine speeds you are seeing, the clutch should really not be a factor. Once the car has run for a couple of minutes, the fan should be rather loose on the clutch -- a rolled-up newspaper should serve to stop it. Also, if you press the STOP lever on the engine, it will stop immediately while the fan should continue to spin for a few seconds. At or above 100C the clutch should stiffen and the fan will then run at engine speed up to about 4000 RPM when the clutch should then disengage.

The servo could cause lack of cabin heat but it should not cause engine overheating. The aux coolant pump could be a contributor, especially if it is clogged with something. A clog or partial clog could also cause your overheating problem.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
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"Oh lord won't you buy me a Mercedes Benz."
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