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Discussion Starter #1
Fan blade, Ok i just had my fan blad come aprart on me.Low rpms sitting inthe garage on a cold start so no damage to sheetmetal. But it cooked the shroud. Since this is my third BMW the first 540 the blade came apart about within 20 miles of 100k, the one on my 540 6 spd has 120k on it and is still fine but i replaced the clutch, My M5 had a wang foooo replacement on it. the M5 just came apart after a high rev when not fully warmed up. But only 1 light left.

How long do these things last? Is there a service schedule for them? Or just prevetative at 100k like the radiator and the surge tanks?
 

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There is no published service interval for the fan clutch. They seem to go, usually without warning, anywhere after 80-100k miles. I changed mine around 95k miles to avoid damage from an exploding fan. It's a relatively easy, inexpensive job though like anything else, it helps to have the right tools (in particular a tool to hold the fan pulley from turning).
 

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Actuly the tool for keeping it from turinig is not necessary. Big open end wrench, steel 3 lbs hammer. Leave belt on and smak it in opposite direction of rotation aboubt 6 times it comes loose every time. for install, Reverse. But thanx again for the info. I was just wonering since these cars have alot of "AIRCRAFT maintance intervals" I was just wondering if there was a callout. I am debating OEM, used oem, or new.
 

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Actuly the tool for keeping it from turinig is not necessary. Big open end wrench, steel 3 lbs hammer. Leave belt on and smak it in opposite direction of rotation aboubt 6 times it comes loose every time. for install, Reverse. But thanx again for the info. I was just wonering since these cars have alot of "AIRCRAFT maintance intervals" I was just wondering if there was a callout. I am debating OEM, used oem, or new.
Ah yes, I'm sure that works but I prefer to use less traumatic means. As for OEM, new or used, if you're talking about the fan itself, probably makes little difference. If the fan clutch, however, I think new, regardless whether OEM or aftermarket. The common failure mode of the fan clutch (as you've experienced) is for it to lock up regardless of temp or RPM. The fan grenades because it can't handle the centrifugal force of the elevated RPM (it's supposed to freewheel past a certain point). If you get a used one, there's no telling how long it's been on the car, so you're rolling the dice on when the lockup problem surfaces.
 

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I would also be inclined to replace the fan as well as the fan clutch. I have not see problems with the fan as of yet, but I had an older Ford Explorer that was about 9 years old, I did not have a problem with the fan or fan clutch, but I noticed when changing the fan belt the fan had small cracks around where the blades met the fan hub. It was easy to see on the Ford as the fan was made of a cloudy white plastic and the cracks were easy to see due to the color of the fan material. I bet if you inspected the M5 fan very closely you might find similar cracks? But they may be very hard to see due to the color of the material.

I look at it this way, plastics harden and get weak and brittle with age, if you go to the trouble to change the fan clutch, you might as well put a new fan on anyway. If you do not replace the fan and it fails, you have to buy a new fan anyway, plus probably more parts and effort replacing anything the fan destroyed. As often as we spin these engines up, for the extra $65-$75 it is probably cheap insurance.
 
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