overheating at idle and slow driving

2004 MERCEDES BENZ E500

35,000 MILES • 5.0L • V8 • 2WD • AUTOMATIC

FARHAN21499

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My car is overheating at idle and slow drive but as long as I am driving on high way temperature stay at normal. things which I have checked myself are, radiator upper and lower hose are in pressure at normal operating temperature and the radiator cap can be open easily. all coolant does not spray out even after driving for long. just confused as to why it is like this? Even after changing the radiator cap it is the same.
Water pump and thermostat is checked by mechanic, it is okay. And there is no leakage. oil is okay and coolant also in radiator up to level.

Nov 25, 2017 at 10:44 PM

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53,855 POSTS

When the engine is overheating can you hear the radiator cooling fan working? If this fan is not working then the engine will overheat at low speeds just as you have described. I would check the fan fuses first and then check the motor by putting power to it and see if it works. Next is the fan control module which when it goes bad fails to operate the fan motor. Here are some guides and diagram (Below) to help us see what the problem is and how to fix it.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

and

https://www.2carpros.com/articles/replace-electric-fan-motor

(Check out the diagram below)

Please let us know what you find. We are interested to see what it is.

Cheers, Ken

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Nov 27, 2017 at 2:10 PM