impeller binding

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  • Last Post 09 August 2017
wherry posted this 24 July 2017

 I have replaced seveal identical pump motors over the years so I am pretty familiar with it. In replacing a 3/4 HP motor on a Hayward Super pump, when I screwed on the impeller and tightened it by hand it resulted in the motor shaft turning with high resistance, unlike previous replacemets I and made. The only difference this time was that I used a salt-water seal. I backed off on the impeller until the shaft turned with little resistance and completed the assembly. (I replaced the housing gasket properly with no problem). When I turned on the power the motor hummed but did not rotate. It occurred to me that backing off on the impeller tightening increased the length of the assembly, so I loosened by a small amount the bolts holding the assembly to the housiing. The motor immediately spun regularly but the he housing gasket leaked. If I retightened the housing bolds, the leak stopped but the motor did not rotate. When I took it apart it appears the the nose of the impeller is pushing against the end of the diffuser.

What is the silution for this.? I believe it must be related to the salt water seal. If the nose of the impeller was even 1/16 inch shorter I would have no problem.

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InyoRob posted this 01 August 2017

The salt seal should have no impact on the assembly and performance of the pump. Sometimes, on the Super Pump, parts from the old shaft seal will stick to the impeller. There may be a metal cuff or a black rubber washer on the impeller shaft. People will assume this is part of the impeller but it is not. Those pieces need to be removed.

wherry posted this 02 August 2017

I removed the old metal cuff before installing the new salt seal.

 

After the impeller is hand tightened during installation is it normal for the shaft to rotate with resistance? How does one know if when the impeller is suffucuently tignt?

InyoRob posted this 09 August 2017

It is normal to have some resistance. Hand tightening the impeller is sufficient. You don't have to crank the impeller on. I use a wrench at the back of the motor to stabilize the shaft. Then I tighten the impeller until I feel firm resistance.

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