I have been working on a noise at 60 to 70 mph in my 500SEL. It seems that it started when the temperature got into the 80's and higher. I finally traced it to the cooling fan. I replaced the fan clutch first part of May with a BEHR because the old one never engaged. I didn't notice the noise until last week.
Should the fan be engaged with the engine at 190 deg, outside temp of 80 deg, rpm at 2500 and speed at 70mph?
I thought the fan clutch would disengage at higher speeds and only engage at higher temperatures.
When the outside temps were say 70 deg or lower I don't have the problem.
If it sounds like I am confused, you are correct.
Is there a break in period for a fan clutch? It has about 1000 miles on it now.

Please help

PaulM

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84 500 SEL (307,xxx miles)