Blower motor rubs fan when tightened down

[jangell]

My blower motor failed with a loud squealing sound, so I replaced it with a cross-over (Advanced Auto had a ToughOne 35582 that cross-referenced for the Four Seasons 35589. I should also mention that while O'Reilly's had a 1980 Chevy Monza motor, it doesn't quite match (different flange and the spindle is too short), contrary to what the crossover says, but it's possible it wasn't an actual match for the Siemens PM106 listed with it in the crossover list).

Anyway, once installed, the fan rubs against the intake housing (the evaporator box, I guess). If I loosen the mounting bolts towards the front of the car, it stops rubbing. I tried loosening all the bolts and shifting it around with the fan running to find a place that would work, but there isn't a lot of play, and I couldn't seem to find a good position.

With the motor not installed, I noticed that the squirrel cage is noticeably wobbling. The shaft is solid and doesn't wobble, so I think the motor itself is good and the cage itself is slightly deformed. It blows air fine, but I'm wondering if the wobble is causing the rubbing noise. I made sure to install that square metal thing on the shaft before installing the squirrel age.

Here's a video of the wobble: https://youtu.be/TRBGQ59mV5I

If I tighten down the two rearmost nuts, and loosen the three towards the front of the car, it runs without making any rubbing noises. That will probably change the first time I hit a bump in the road, though. I'm thinking of installing a gasket between the flange and the evaporator housing to add a little space so I can snug the bolts down but still leave a bit of extra space to avoid the rubbing. Or I could put a washer or two between the square thing on the shaft and the squirrel cage to shift it up a bit instead (I might just do that; it seems easier, and there's still plenty of thread for the nut on the top).

Anyone ever having anything like this happen before? I thought of ordering a new squirrel cage, but I'm fairly certain those aren't available anymore, and it's not in that bad of shape, really.

-- Joe

[DMC5180]

The wobbly cage is somewhat common unfortunately.

One thing you could do, is find the spot in the housing opening where the contact is happening. Then file or sand the plastic back till it has clearance.

Place masking tape one layer thick around the inside of the opening. Re install the motor and run it. Pull it back out and look for a witness mark. Remove material as needed. As I recall, that opening is hand cut to begin with. Also the blower housing is bolted to the inlet around perimeter of the circle. If the circles aren’t in perfect alignment, you may be able loosen the fasteners and re-center it.




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[David T]

Make sure that you placed the special washer onto the motor shaft properly BEFORE you put the "cage" onto the shaft. If it still wobbles you may have to replace the cage. It should not wobble so badly. Maybe you got that washer on upside down?

[jangell]

I took the blower out and tried again. I did put on that special washer, but it flew off when I removed the cage so I don't know if I put it on right side up or not. I'm pretty sure I did, since the blower didn't want to fit in the box when I intentionally put it on upside down (the cage hit the top of the inside of the box). Adding extra washers didn't work either, since the the special washer's "teeth" that hold onto the cage add too much height once the washers are placed on top.

I put everything back in the with the intention of doing the masking-tape-and-sanding suggestion another day, and the motor worked fine with no scrapping after snugging four of the bolts in. The fifth (and hardest to reach) one doesn't QUITE want to fit more than a turn or so, but it's snug enough and everything is sealed pretty well, so I'm leaving it alone for now.

I'm wondering if I cross-threaded one or more of the bolts when I put it together earlier, which pushed the motor to one side a bit and caused the blower to rub. I'm not really sure, though.

I of course didn't think to shoot another video of the motor running to see if the cage is still wobbling or not, but now I don't want to pull it out again, since it seems to be working. I'll keep an eye on it and see if it starts acting up.

Thanks!

-- Joe