Pentair Superflo Broken Shaft

[TYoung3]

Looking for expert advise on what caused my Pentair pump shaft to break. I've read a couple of other posts where this has happened, but those breaks were clean - almost looking as if they were cut on a lathe. That's not the case with mine. This pump is almost exactly 10 years old and ran 24 x 7 x 365 with the exception of servicing the pool. This last year, there would be air in the volute strainer but the pump was still pushing water. Turning the RPMs up on the pump would resolve this issue - at least temporarily. Because it was still moving water, even at the lower RPMs I wasn't concerned with the air in the strainer. That may have been a mistake.

Additionally, when I disassembled the pump side of things, I discovered I was missing the screws which hold the diffuser to the seal plate. The metal inserts in the seal plate were not there either. These parts were not found. No idea where they are. Having never been inside one of these pumps before, it wasn't until I was watching a video on replacing the seal that I realized these were missing.

I intend to rebuild this unit and have already purchased a well used motor with a nice shiny shaft. I found it on ebay and picked it up for $90 including shipping. I was planning to rebuild the pump side and had already purchased seals, diffuser, impeller along with bearings for the motor. I'll need a new seal plate, diffuser screws and the black piece of rubber that goes up against the motor on the shaft (not sure what this is called or of the part number). The last picture, shows an additional part needed, but that piece of metal that goes on the shaft up against the impeller. My intention is to disassemble the the motor I purchased, pull the rotor / shaft, replace the bearings and install into my motor housing.

As I stated when I started the post, I'm wanting to understand what caused this problem so I can prevent it in the future.

Thanks,

Tripp

 

[PoolStored]

Probably a long term shaft seal failure that allowed the shaft to corrode.

Ensure that you have proper seals, and monitor the pump for ANY leaks. Replace o-rings and seals anytime you find a leak. That's your best approach to avoid in the future.

 

[JamesW]

Show the system.

 

[1poolman1]

Looking for expert advise on what caused my Pentair pump shaft to break. I've read a couple of other posts where this has happened, but those breaks were clean - almost looking as if they were cut on a lathe. That's not the case with mine. This pump is almost exactly 10 years old and ran 24 x 7 x 365 with the exception of servicing the pool. This last year, there would be air in the volute strainer but the pump was still pushing water. Turning the RPMs up on the pump would resolve this issue - at least temporarily. Because it was still moving water, even at the lower RPMs I wasn't concerned with the air in the strainer. That may have been a mistake.

Additionally, when I disassembled the pump side of things, I discovered I was missing the screws which hold the diffuser to the seal plate. The metal inserts in the seal plate were not there either. These parts were not found. No idea where they are. Having never been inside one of these pumps before, it wasn't until I was watching a video on replacing the seal that I realized these were missing.

I intend to rebuild this unit and have already purchased a well used motor with a nice shiny shaft. I found it on ebay and picked it up for $90 including shipping. I was planning to rebuild the pump side and had already purchased seals, diffuser, impeller along with bearings for the motor. I'll need a new seal plate, diffuser screws and the black piece of rubber that goes up against the motor on the shaft (not sure what this is called or of the part number). The last picture, shows an additional part needed, but that piece of metal that goes on the shaft up against the impeller. My intention is to disassemble the the motor I purchased, pull the rotor / shaft, replace the bearings and install into my motor housing.

As I stated when I started the post, I'm wanting to understand what caused this problem so I can prevent it in the future.

Thanks,

Tripp

Do you have a tablet feeder in the system? That appears to be chemical damage. If the diffuser screws are gone and the brass inserts as well, that is definitely chemical damage. Chemical damage also occurs to the spring on the seal (yes it is stainless, no that isn't good enough) the spring gets weak and the seal leaks Did you see water below the pump and not know where it was from. That is usually sign of a damaged seal that needs to be corrected ASAP, water damage doesn't wait 'til next year.

Black piece of rubber (disc) that goes over the shaft that may or may not stay at the motor, is a water slinger. For motors on in-ground pumps they are all the same size if you are going to try an get one. Helpful in some cases but not absolutely needed and if yours isn't there that's completely normal for a pump that age.

The last picture is of the impeller with the remains of the "bellows" portion of the seal still stuck to the impeller. Lightly (very lightly) lube the new impeller shaft before sliding the bellows on, it will seat better.

Picture to its left is the complete assembly minus the rubber cup that carries the ceramic and that goes into the sealplate. A very light coating of lube on it will allow it to go into the sealplate easier. The cup is still in the sealplate and probably very hard. You don't reuse seals so just toss it.