I replaced one on my e39 that was seized (same cooling system as e53). If you have to replace, stick to the OEM part.

I bought a 'will fit' part off eBay for about $600......it bolted up fine and worked as intended - but it didn't have a connector on the wiring so I had to splice in the old connector.

And then I found that during operation with the hood closed - the 'nostril' holes that are in the factory shroud would push against the fan housing, which would then push the fan against the radiator.

Long story short, the fit was off, and it would cause the fan to rub in hot weather (plastic must have softened enough to deform) and make a sound like a paying card hitting against the spokes on a kid's bike wheel.

+1 for OEM.

If you've got your old fan, can you get the motor reconditioned? An auto electrician might be able to help?

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2005 3.0d Sport - Sapphire Black
Engine : Bluefin Superchip Tune,
Wheels & Sus: Style 168s (10.5s all round), H&R RDA Spacers, Bilstein B12, Eibach 40mm drop, Whiteline RSB
Exterior: Le Mans flares, 4.6is kit F&R
Interior: Dynavin N6, Blackvue DR650 dash cams

My Build Thread: http://www.xoutpost.com/bmw-sav-foru...run-sheet.html