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Thread: Pump losing prime/not performing properly - pump failing?

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    Question Pump losing prime/not performing properly - pump failing?

    Have been doing lots of reading through of old threads, but not quite able to identify my issue.

    My pump has been losing prime almost everyday for the past few days. It will sometimes pause and reset itself and regain full prime, but most often, it will just gently suck in water and not reach full performance. Basically the housing/basket will just barely any water visible, not pumping fully.

    I thought it might be a leak, but wonder if it's the pump itself? The pump is at ground-level (single speed 1.5 HP Sta-rite) and connected directly to the skimmer (no weir flap). Please see pictures album here. Only one suction point at the skimmer and no valves/diversions from the skimmer to the pump. There's plenty of water and no vortex. We usually use a suction side vacuum (The Pool Cleaner), which I've disconnected for now. Replaced the o-ring gasket on the pump housing lid and inspected the drain plug.

    The pump failed about six months ago, but reading up here at TFP, replacing the start-up capacitor fixed things and it was running smoothly. We had the pump rebuilt about ~eight years ago with seemingly similar issues of operating at a bare minimum speed, so I'm not sure if it's failed again.

    I've never opened up the pump itself myself, but wanted to see if there might be something else awry first.

    Thanks!
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    mas985's Avatar
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    Re: Pump losing prime/not performing properly - pump failing?

    Sounds like it could be an air leak or perhaps there is something stuck in the impeller. Did you try to clear the impeller inlet first?

    What is the filter pressure when running? If higher than normal, it could also be a dirty filter.
    Mark
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    Re: Pump losing prime/not performing properly - pump failing?

    More here on tracking down a suction leak, Pool School - Suction Side Air Leaks
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    Re: Pump losing prime/not performing properly - pump failing?

    Quote Originally Posted by mas985 View Post
    Sounds like it could be an air leak or perhaps there is something stuck in the impeller. Did you try to clear the impeller inlet first?

    What is the filter pressure when running? If higher than normal, it could also be a dirty filter.
    Thanks, I'll give the impeller a crack. Looked up the process on Youtube, does it require disassembly of the housing?

    I see this instructional video that just uses a brush like device from the basket end of the housing, while this video takes the housing apart at the metal clamp to fully reveal the impeller

    Thanks for mentioning the filter pressure, I wonder if that's somewhat related, as we just cleaned it out over the weekend. It was pretty filthy with dirt and dust build-up. It's operating at about 12-16 psi, including flow up to the solar blankets.

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    Re: Pump losing prime/not performing properly - pump failing?

    You can first look at the impeller inlet under the pump basket. Just use your fingers and see if anything is stuck in there. If not, then yes, open the pump and check the impeller itself. Look down each vane and make sure it is clear.
    Mark
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    Re: Pump losing prime/not performing properly - pump failing?

    Quote Originally Posted by pooldv View Post
    More here on tracking down a suction leak, Pool School - Suction Side Air Leaks
    Thanks, that was the page I saw many folks referenced, and where I got the idea of checking the drain plug.

    Gauging from how significant this is, with the pump barely running above idle, I sense it's not quite just a suction side leak -- we've experienced that several times in the past with the vacuum hoses cracking. The pump, in those instances, would just lose prime, reset itself in a minute or few, then return to full operations. It seems that this time around, the pump doesn't quite reach that steady priming/reset process

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    mas985's Avatar
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    Re: Pump losing prime/not performing properly - pump failing?

    Then I would check the impeller for blockage.
    Mark
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    Question Re: Pump losing prime/not performing properly - pump failing?

    Quote Originally Posted by mas985 View Post
    You can first look at the impeller inlet under the pump basket. Just use your fingers and see if anything is stuck in there. If not, then yes, open the pump and check the impeller itself. Look down each vane and make sure it is clear.
    Thanks. Alas, the impeller is all clear. Fished around with my fingers, then we opened up the housing. Only a bit of DE powder.

    After we manually re-primed the lines and started it up, it ran perfectly for a bit. Powered off and tried again and it returned to its original condition, barely operating...

    Here are some pictures of the disassembly and impeller.

    Also filmed a quick video clip, uploaded here to Youtube.

    Talking with my dad, he wonders if it's a start-up capacitor issue again, the same as that died several months ago. Unfortunately, I don't recall how quiet/barely operational the pump was back then, i.e. if the symptoms are identical...

    Any ideas appreciated

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    Re: Pump losing prime/not performing properly - pump failing?

    The pictures you posted were of the diffuser not the impeller. The impeller is attached to the motor shaft.

    You need to remove the diffuser to get to the impeller.
    Mark
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    Re: Pump losing prime/not performing properly - pump failing?

    Quote Originally Posted by mas985 View Post
    The pictures you posted were of the diffuser not the impeller. The impeller is attached to the motor shaft.

    You need to remove the diffuser to get to the impeller.
    Yea we removed those four flathead screws on the diffuser cover and poked around at the impeller. It was all clear and the shaft rotated without issue

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    Re: Pump losing prime/not performing properly - pump failing?

    Does the pump get extremely hot before it shuts down to reset?

    That would signal it may be the capacitor again.
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    Re: Pump losing prime/not performing properly - pump failing?

    Quote Originally Posted by charlieTX View Post
    Does the pump get extremely hot before it shuts down to reset?

    That would signal it may be the capacitor again.
    Nope, no overheating anywhere.

    We finally gave up and called a service guy -- he discovered the pump suction inlet connector is just a touch loose and leaking air

    The problem now is, there's so limited space to cut open the PVC and replace things. See attached image

    There's really no space to cut the 1.5" PVC and resplice in a coupling up to the elbow.

    Looking at the bottom where the PVC joins with the copper piping, it looks to be custom copper to PVC screw on adapter/unions. I'm thinking I can cut at the 1.5" PVC and just unscrew this upper adapter of the union, then glue in a new piece of PVC pipe with a new male adapter (MPT x Slip). The problem is, looking at the pictures of the copper/PVC adapter at the PVC male adapter, it may have some special o-ring or other gasket design to keep it sealed with the copper end.

    If that's the case, I don't know how I'll be able to locate a male fitting (MPT x S) that works here. I see a few straight male adapters at Home Depot, but without that o-ring/additional layer of sealing with the female copper end.

    I'm just afraid I find a general male adapter that screws into the existing copper adapter, then glue in my PVC pipe to the male adapter, it'll be easy to throw an elbow and some fittings to screw it back into the pump inlet. But I'm worried the standard male adapter will not form a seal with the female portion of the custom copper-PVC union, resulting in leaks later on...

    Any tips appreciated
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    Re: Pump losing prime/not performing properly - pump failing?

    How about cutting the copper pipe, unscrew the complete section from the pump, remake the plastic joint to the pump and then rejoin the copper pipe
    You will need to excavate the ground a bit
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    mas985's Avatar
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    Re: Pump losing prime/not performing properly - pump failing?

    I would cut the PVC between the fittings and wrench off the rest of the PVC from the copper.
    Mark
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    Re: Pump losing prime/not performing properly - pump failing?

    Quote Originally Posted by denniswiseman View Post
    How about cutting the copper pipe, unscrew the complete section from the pump, remake the plastic joint to the pump and then rejoin the copper pipe
    You will need to excavate the ground a bit
    Thanks, I'd be glad to replumb with a new copper-PVC adapter, not sure cutting the copper pipe is necessary?

    Quote Originally Posted by mas985 View Post
    I would cut the PVC between the fittings and wrench off the rest of the PVC from the copper.
    Thanks, do you mean replace that copper-PVC adapter/union? I might have to special order this adapter as I didn't see it in the online catalogs of my local box stores (HD and Lowes)

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    Re: Pump losing prime/not performing properly - pump failing?

    You could first try to cut right below the elbow and then if you can take off the union, you might be able to reuse it if there is enough room to slide it down for a coupler or up for a new elbow.

    But you would probably be better off with a new union.
    Mark
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    Re: Pump losing prime/not performing properly - pump failing?

    You could remove all the plastic, sweat in a copper 45 elbow facing away from the pump on the existing copper, then sweat in a suitably long piece of straight copper with another 45 and a street elbow on the other end to get you up to the input level of the pump and turned in towards the pump. Attach the PVC there with a union and get a straight horizontal run into the pump body. This will take up a little more space, but looks like that isn't a problem in the picture.

    Some people run for the hills at the thought of sweating copper, but it's not much harder than PVC joints.
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    Re: Pump losing prime/not performing properly - pump failing?

    I think I would cut the inlet pipe at the bottom of the elbow and push the pump back so you have more space on the horizontal run. It looks like you have enough pipe on the run to the filter to re-position the pump. I would replumb with unions on the inlet and outlet to make it easier to service the pump in the future. It would also be a good opportunity to install a valve on the inlet line. I hate seeing equipment pads plumbed so tight you can't work on anything without have to re-do the plumbing.
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