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Tim

Tim 5/7/2014

1998 BMW 750iL Base 12 Cyl 5.40L

Engine

All my radiator fan blades are broken.

While I was excelerating the fan blades broke off. The fan had plenty of clearance so it wasn't rubbing on anything. What caused this and can it be stopped?

3 Answers


GT500Knights

GT500Knights 5/7/2014

Were you using a flex fan? Those are only made to run up to a certain rpm. Was it the kind that attaches to a clutch? Perhaps the shaft for the fan was bent slightly causing the fan to spin out of balance? It must have hit something.

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Tim

Tim 5/7/2014

Yes I was using a flex fan. The kind that attaches to the clutch. It hit the shroud. Before this happen I heard a pop then the blades breaking.

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GT500Knights

GT500Knights 5/7/2014

With clutch driven fans, they are made to be used with the stock, or a non-flexing fan. The silicon fluid inside the clutch, along with a bimetallic spring mounted in front, controls how much the fan should spin, or how much slippage should occur. With a flex fan, they are not usually designed to be used with a clutch mechanism. Instead, a spacer kit is used to provide the fan the proper clearance and proper distance from the radiator. Were you using a fan clutch along with a spacer kit, with the fan clutch? It is also possible the engine mounts may be worn out. I know my vehicle had sagging engine mounts, and the fan blades began to brush against the lower fan shroud, causing a sort of clickety clackety sort of tapping sound.

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