On my 2003 X54.6 I did a complete cooling system-ectomy.
I also researched a better clutch fan. I tried a fan for a BMW 750.
It bolts right up to the blade. I must have gotten a defective unit, because
it would heat up and not lock up. The brand was Behr.

I removed that unit and bought a Sachs 2100 011 031.
It also bolted right up. This new clutch fan sucks!
In a really good way!
The 4.6 original fan and blade
have been redesigned and NLA. I didn't want to buy a clutch and fan.
This part I have now really draws the air.
My electric fan is just loafing along being on standby for a severe traffic jam.

Where I live Dallas 100 degree days are common and traffic can get snarled.
I'm glad I have a new and now perfect cooling system.

I bought the part on Amazon and it is about 6 months old according to the
manufacturing date.

PS I did try an aftermarket fan blade. I think it was Meley brand.
What a POS. Warped, out of round and terrible mold.
I'm sending this junk back.

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2003 4.6is X5
2003 525it
2003 E53 X5 Standard shift