I just completed a cooling system overhaul on my '98 BMW. This included replacing the fan and fan clutch as preventive maintenance. While checking my work, I noticed the fan appears to have a little bit of a wobble towards the outside of the blades. Is this amount of variance pretty normal in these more old school fan systems? I think the video accentuates it a bit but it gets the basic point across. The fan clutch, water pump bearing, and even the center of the fan appear to spin very smoothly and without a wobble. I also don't notice any odd sounds or vibration, in fact it feels smoother than before the overhaul. I inspected the fan and do not see any cracks or bent blades. I don't mind it, in fact I'd rather not have to take it back off! I just want to make sure it wouldn't cause damage like prematurely wearing out the water pump bearing.
Acceptable Amount of Tolerance for Clutch Fan
- Thread starter cutlassvillager
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- Jun 2, 2002
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The wobble to be concerned with is in the bearing which is housed inside the viscous coupling. You will see wobbling at the cooling fins if there is any play in the bearing and you will hear it if it's bad enough.
The plastic fan blades distort just from being spun around and having a load placed on them. I wouldn't worry about that aspect.
The plastic fan blades distort just from being spun around and having a load placed on them. I wouldn't worry about that aspect.
If the look at the middle of the fan while it rotates there is hardly any movement at all, its probably blade flex or slight imbalance in the blades, just a couple of grams heavier or lighter will cause that. You can have up to 6mm play in the viscous clutch center to blade end.
I wouldn't worry about it at all.
I wouldn't worry about it at all.
Great, I had a feeling I was maybe over-analyzing it a bit. Thanks FowVay and Trav for the clarification!
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