OK, I have a dumb question and I apologize for having to ask it, but I have been away from this forum for a long time and my knowledge is rusty.

I notice my engine sounds louder on hot days. Like there is a big fan attached to it. Is this because the radiator fan clutch is engaging and the fan is spinning at or near the same speed as the driveshaft?

Also, I had a weird thought. About two years ago I removed the the fan to do some repair I cannot recall. Is it possible to put the fan on backwards? Should the fan be blowing air at the radiator or sucking it away?

I am not sure which way mine is blowing, and since it is cooling properly I don't really care, but just a couple of dumb questions for the forum on a nice, hot, Monday in Virginia.

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2008 E350 4matic / Black/Anthracite

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Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black