Pump shaft bent

Just took motor to shop and found out the shaft is bent. Symptom was shaft not turning and motor making that starting noise until I banged on the motor. (I don't recommend that solution to anyone) The cost to straighten the shaft (if they can) pretty much equals the cost of a new two speed pump.

I actually have two questions. The first one is could excess debris getting into impeller or adding DE medium too fast cause the shaft to bend under pressure?

The second question is based upon me looking at older threads and saw a comment about when switching a motor off and the shaft spinning freely. Should the shaft spin freely when the pump is turned off, slow down fairly quickly or come to pretty much an abrupt stop?

Thanks ahead

Wow....takes a bit to bend a piece of steel like that. Would sure like to know what caused it.

Debris in the impeller or any amount of DE should not bend anything. Hard debris like nails, screws, bolts, etc. could gouge or destroy the impeller and housing. It is probably possible to bend a shaft if something BIG and hard, like a bolt, gets past the baskets and jams the impeller while it is up to speed.

As for spinning down when turned off....if it was pumping water when power is cut it will stop fast. If dry then it will wind down over many seconds. When pumpig water it is under load but dry it should just turn freely.

As for bending the shaft by beating on the motor case, I doubt it.

I did bend a shaft one time on a Hayward AG pump but I was trying to press off the fan to get to the bearing behind it. Rusted real bad. The 20 ton press won and the shaft lost and the rust never did break loose and that was after trying every rust breaking trick I know. Replaced it with a good Superpump.

Al

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Originally Posted by let_her_flicker

Just took motor to shop and found out the shaft is bent. Symptom was shaft not turning and motor making that starting noise until I banged on the motor. (I don't recommend that solution to anyone) The cost to straighten the shaft (if they can) pretty much equals the cost of a new two speed pump.

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Well, nothing is impossible such as a very poor tempering job on the shaft but if we really look at your situation; the "shop guy" said...

Take it for what it is worth but I would like to know how the "shop guy" made this determination that a half inch shaft is bent.

As was mentioned, you should not have an impeller with a bent shaft not only because a rock or whatever would have torn it to shreds but also, the clearance between the shaft and the housing is very small so that the impeller should have beaten itself to death while smacking the housing.

Could we possibly have a bad capacitor and a disreputable "shop guy"?

Did the motor make weird noises when it ran after smacking it? If not, I can't fathom a bent shaft for that reason alone, let alone the destroyed impeller that does not exist.

Searcher, very good points. I'm normally a suspicious guy but this time I just never questioned the 'shop guy'. I should know better. I have a feeling you're right.
Al

Hi - The "shop guy" works at a local electrical motor company and his expertise is small motors. He is the one that replaced the bearings in this motor last year. He also reminded me to replace the seal in the housing as they can go bad (especially after replacing a bearing). He replaced the seal and only charged me for the part.

The pump did not sound right when running in the high speed. At low speed it did not make any kind of sound leading you to believe there was something wrong with the motor.

When I stopped the pump and then restarted it, that is when the motor would freeze up. The noise made is the one when a motor has power, but unable to turn the shaft. A few times it actually shocked me through the switch when turning it on. (115 volts) Since I have a fairly serious case of peripheral neuropathy, I did not jump through the roof when it happened.

When we looked at the shaft in the shop, it spun freely and quietly with a wobble. When placed in the housing, it did not spin freely. Strange things happen. Fortunately, I have a friend who is a plumber and works on pools/spas on the side. He has a two speed motor that draws 12 amps in high speed and 3 amps in low speed.

I appreciate both of you taking time to respond to this problem.

This is probably one of those problems that we'll never fully understand. One issue, if you got shocked then something isn't grounded right and I would check on this with the new motor too. Hope it works out for you.
Al