Cold medal

I have a 2003 BMW E39 525dSE auto Touring that appears to have a problem of overcooling. It can take up to 10 miles to reach normal working temperature, summer or winter. At that point, descending hills or time spent idling will result in a fall in the temperature gauge reading. I have had the thermostat checked by my BMW dealer and, although it was working correctly, I had it replaced in case it was sticking in a partially open position. This has made no difference. I am wondering whether the fan is cutting in too early. It might be a problem that you have come across with this model, and I would be most grateful for your thoughts on this matter.

Asked on 14 March 2009 by

Answered by Honest John

It's normal for a diesel to take a long time to reach running temperature in this weather. But not in summer. In summer it should get to temperature in 2 - 4 miles. Might be an idea to replace the fan thermo switch, which you will find screwed into the water jacket somewhere. Just follow the cables back from the fan motors.

Tags: thermostats technical issues owning engine

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