wicks

Hi - I just replaced my alt belt (and about to do new A/C belt). After cleaning and reassembling and shimming out the pulley to correct tension, while rotating the A/C belt pulley, I notice the fan oscillates maybe 1mm (measured at the end of fan blades at housing) as the shaft rotates. I wonder if this means I have a bent alternator shaft? It seems the alternator has been replaced on the car at some point.

If alt shaft indeed bent, should I expect damage to anything to result? The fan bearing does not have much play - checked that when apart. Less play than the AC compressor pulley when un-clutched.

P-daddy

wicks

This is like a brain teaser. I drew an exploded diagram to try to prove to myself it could be something other than a bent alt shaft. It cannot. I think...

Key fact: this is with the fan stationary. Just the alt shaft rotating.

wicks

Another theory: the fan and the fan pulley (which is bolted to the fan) oscillate together. The A/C belt pulley and shaft do not visibly oscillate. When I turn the shaft (and not the fan), the fan inner race is turning, but the outer race is not. So: the fan inner race is a bit crooked on the alternator shaft.

If this is true - can I apply heat and straighten said inner race on the shaft?

Rocket Rob

Could there be dirt or grit under the fan hub causing it to be slightly off kilter?

If it were my car, I would pull the fan and alternator to inspect everything individually.

wicks

Dirt or grit would have to be under the fan inner race, wouldn't it?

Rocket Rob

Yes, its not very likely to happen after installation but if the part fan bearing was dirty when the fan was pressed on.....

wicks

Just discovered there's a hub, with the actual bearing inside of that. And the fan is mounted to the hub - so I am thinking the fan is just a little crooked on the hub. Maybe I can use some spray liquid nitro on the hub and some heat on the fan to get it loose for straightening.

Rocket Rob

Yes, there is a bearing at the center of the fan. Over time, that bearing can wear out. Before replacing the bearing be sure to fully inspect your fan. Mine had several cracks starting at the base of the blades. I decided to replace the fan itself. New fans come with a bearing/hub already pressed in.

wicks

I have a very 'young', clean car. 35K miles, lived parked in a collection most of it's life. So it's not dirt, and it's not wear. No cracks in anything but the power seat bushings.

Rocket Rob

Congrats on having such a young car. Both of my cars have a lot of miles.

wicks

Here is a video showing the oscillation:

Richard H

My money would be on this rather than a bent shaft. Problem is that if the bearing was pressed on out of square the shaft may be damaged anyway.

AOW162435

PM sent.




Andreas

John McM