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Thread: Trying to diagnose a Hayward RS750 pump

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    Trying to diagnose a Hayward RS750 pump

    Hi,

    Just yesterday, I believe my pump overheated and stopped running. After I allowed it to cool down and tried turning it on again, it doesn't seem to have the same suction power. I've emailed Hayward for a manual so I can try to see if that would help. But since I've always found this forum so helpful, I thought I'd send a note out here.

    Some background. Bought this house in October. Have been periodically cleaning the pool with the pump running about 1-2 hours a day. Couple weeks ago, I cleaned out the filter and had the pump running for about 5 days straight. Just 3 days ago, I backwashed and cleaned the filter again and started shocking the pool. Then the pump failure. Now when I turn it back on, there's a low murmr, not the usual "roar".

    Could I have put the fitler back in incorrectly? Could there be a clog in the suction line?

    Thx.
    -Rich
    20k Gallon IG, Hayward 1.15HP RS750 Pump, Purex Triton Nautilus FNS 48 DE Filter, Polaris 280 w/ PB4-60 Booster Pump.

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    spishex's Avatar
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    Re: Trying to diagnose a Hayward RS750 pump

    It sounds more like a motor problem then a system problem, but it could be that one caused the other. Try the pump for just a minute with the strainer lid off so it's not pushing water. Does it still just groan or does it sound normal? You could have a bad run capacitor, in which case you'd follow the advice I just gave in another thread:
    If the shaft of the motor spins freely by hand you might be able to get away with replacing the capacitor(s). They're black cylinders, about the size of D-cell batteries, and are housed either under the back plate where your wires connect or under a bulging plate on the side of the motor. If you have a pic handy I'll point them out for you.
    You should also check the impeller for blockages.

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    Re: Trying to diagnose a Hayward RS750 pump

    When I took the strainer lid off and turned the pump on it sounded more "ok" than not. But then again, I'm used to hearing it with the lid on and "roaring". I also finally replaced the broken pressure gauge and put the new one it. The highest reading is 5 PSI. I also checked the impeller and it didn't have any blockages. I was also able to turn the motor shaft which is shown in the image "Pump Shaft Turns.jpg". Based on all the information, does it sound like replacing the capacitor would do the trick?

    Pump Capacitor.jpg:
    http://www.linzarni.net/pool/Pump%20Capacitor.jpg

    Pump Shaft Turns.jpg:
    http://www.linzarni.net/pool/Pump%20Shaft%20Turns.jpg
    20k Gallon IG, Hayward 1.15HP RS750 Pump, Purex Triton Nautilus FNS 48 DE Filter, Polaris 280 w/ PB4-60 Booster Pump.

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    Re: Trying to diagnose a Hayward RS750 pump

    Maybe. You said it doesn't have the same suction power. How's the water coming out of the returns? I'd be surprised to even see 5 psi from a motor with a bad capacitor, but that could be the case.

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    Re: Trying to diagnose a Hayward RS750 pump

    Nothing comes out of the farthest return. The middle return seems at about 1/2. The closest seems at about 2/3 of normal. But of course this is all with the motor being run for a minute or two before I turn it off.
    20k Gallon IG, Hayward 1.15HP RS750 Pump, Purex Triton Nautilus FNS 48 DE Filter, Polaris 280 w/ PB4-60 Booster Pump.

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    Re: Trying to diagnose a Hayward RS750 pump

    One last question , you say you backwashed and cleaned the filter and shocked, and then the pump failure. How long between the two? Did the pump work ok for a while first? If so then it sounds like a motor issue to me and I'd try the capacitor. It's a pretty easy, cheap job. Just keep your fingers off the terminals since it could still hold a charge.

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    Re: Trying to diagnose a Hayward RS750 pump

    The pump ran for 24 hours after I backwashed and cleaned the filter and shocked the pool. But as you know from my other post, I did not backwash for long since I needed to shock the pool. So for a timeline, I backwashed for a total of 5 minutes maybe. Cleaned the filter after that. Re added DE while turning the pump on. Then shocked the pool about 30 minutes after that. Then the failure happened about 24 hours after that.
    20k Gallon IG, Hayward 1.15HP RS750 Pump, Purex Triton Nautilus FNS 48 DE Filter, Polaris 280 w/ PB4-60 Booster Pump.

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    Re: Trying to diagnose a Hayward RS750 pump

    Hmmmm...

    Too bad you just have that push/pull valve. I'd love to know what it would do bypassing the filter. The more I read over this the more I think I just got stuck on the capacitor thing because of the motor making a murmur instead of a roar and the other thread that happened to show up at the same time. The noise difference could just be primed vs. not primed, and then we'd probably be looking at a filter issue. That's even more likely since it sounds ok when not trying to pull water (strainer lid off).

    I think my next step would be to try it in backwash. You'll lose some DE but it may be that you added too much or that the grids are already covered in filtered debris. You could also break it down and run it with the grids removed.

    Sorry for the waffling

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    Re: Trying to diagnose a Hayward RS750 pump

    Sometime last week after the murmur started, I did try back washing it just to see how it behaved. The pressure would intermittently drop. I made sure there wasn't any air in the filter by releasing the air bleeder valve. Wouldn't that keep it primed?

    No problem with the waffling. I'm just glad to be getting advice.
    20k Gallon IG, Hayward 1.15HP RS750 Pump, Purex Triton Nautilus FNS 48 DE Filter, Polaris 280 w/ PB4-60 Booster Pump.

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    Re: Trying to diagnose a Hayward RS750 pump

    No, that wouldn't necessarily keep it primed. I think you're going to need to take the filter back apart. Even if it loses pressure on backwash it is at least getting up to pressure, so the motor sounds fine. If you added the DE through the skimmer it may have clumped in the line.

    You didn't add the DE with it in backwash did you...? No, you'd see that coming back into the pool.

    I say take it apart and clean the grids well. With the amount of cloudiness in your pool it could have filtered as much as it can take.

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    Re: Trying to diagnose a Hayward RS750 pump

    Ok. I'll take the filter out and clean it out again. Gotta go buy more DE first. If there is DE clumped in the suction line, what would be a good way to un clump it? Because the water going into the pump's basket definetly isn't what it used to be.

    I did not add DE when backwashing. The only time I added DE was after each time I reassembled the filter.
    20k Gallon IG, Hayward 1.15HP RS750 Pump, Purex Triton Nautilus FNS 48 DE Filter, Polaris 280 w/ PB4-60 Booster Pump.

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    Re: Trying to diagnose a Hayward RS750 pump

    The water going in is dependent on water going out, so it doesn't necessarily mean the problem is on the suction side. But if it is, it wouldn't be hard to push through with a drain king (hose attachment) or a snake.

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    Re: Trying to diagnose a Hayward RS750 pump

    Do you have a "Bypass/Recirculate" ability on your filter, simply bypassing the filter would be easier if posible than pulling it apart
    would allow you to rule out a clogging/ back pressure problem

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    Re: Trying to diagnose a Hayward RS750 pump

    Nope. He's got a push/pull valve.

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    Re: Trying to diagnose a Hayward RS750 pump

    Finally got around to opening the filter. It was in pretty good condition. But a couple observations. 1. The water level was pretty high. Almost up to the top of the bottom half of the filter. 2. There was a fair amount of DE on the bottom of the filter (i.e not on the filter wings).

    I scooped out the DE and rinsed out the filter wings and the housing. I then put the filter back in and closed it up.

    Previously, I removed the capacitors and tried looking around for a store. No luck yet. Went to Leslie's and they said they can special order, but it'd take about a week or 2 for standard shipping and it would cost around 25-50 depending on the capacitor. Seemed a bit high. So I just put the same capacitors back in.

    Turned everything on. Now the motor makes more of a clicking sound and all previous symptons are the same. Saw the video on replacing capacitor and the link for disassembling the pump. Is it time to disassemble past the impeller. I don't believe I did that last time. Previously, all I did was remove the 6 nuts to detach the 2 parts of the pump from each other.
    20k Gallon IG, Hayward 1.15HP RS750 Pump, Purex Triton Nautilus FNS 48 DE Filter, Polaris 280 w/ PB4-60 Booster Pump.

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    Re: Trying to diagnose a Hayward RS750 pump

    Yes, take it down to the impeller and check for any debris stuck in the veins.

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    Re: Trying to diagnose a Hayward RS750 pump

    I ordered a new run capacitor and replaced the old one, still the same results. I removed the impeller and inspected it for debris or defects, none visible. The next thing I will check is the suction line with the "drain king" as you recommended. As always, any other advice would be definetly appreciated.
    20k Gallon IG, Hayward 1.15HP RS750 Pump, Purex Triton Nautilus FNS 48 DE Filter, Polaris 280 w/ PB4-60 Booster Pump.

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    Re: Trying to diagnose a Hayward RS750 pump

    I didn't find any clogs in the suction line using the "drain king". While I was reassembling the impeller, I noticed one of the wires connecting from the "start" capacitor was loose. I was able to solder it back on. I did not notice this when I removed the "start" capacitor couple weeks ago. At this point, I don't know if that was the cause, but I'm hoping for anything at this point. Losing hope....

    Also, does anyone have any idea why I can not find any sites that sell parts for the RS750? Is this specific to Leslie's?
    20k Gallon IG, Hayward 1.15HP RS750 Pump, Purex Triton Nautilus FNS 48 DE Filter, Polaris 280 w/ PB4-60 Booster Pump.

  19. Back To Top    #19
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    Re: Trying to diagnose a Hayward RS750 pump

    You're not to lose hope, dc_dick.

    That could be the problem. I've seen a motor in the past that was overheating after about 15 minutes because of a loose connection at the capacitor. There was some obvious burning around it.

    As for the parts, try searching a couple of the part numbers you do have: strainer basket, lid, impeller, etc.

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    Re: Trying to diagnose a Hayward RS750 pump

    Thanks for the word of encouragement.spishex, however, after connecting the pump back, I'm still not having luck. Plus I don't know if I screwed something up upon reassembly. The sound is different now, but the original problem seem to still exist. It's safe to say, it's time to call someone else to come and look at this. Hopefully it doesn't end up costing a fortune.

    I did notice this hole on the bottom of the cover. Can't say if it's normal or not.
    [attachment=0:3o6k2bid]Hole below impeller.jpg[/attachment:3o6k2bid]
    Attached Images Attached Images
    20k Gallon IG, Hayward 1.15HP RS750 Pump, Purex Triton Nautilus FNS 48 DE Filter, Polaris 280 w/ PB4-60 Booster Pump.

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