Pump diffuser removal

[DishoomX2]

Hello!

I'm new to the forum and hope some experts can weigh in on an issue I have.

I've been having an issue with suction-side air leak and cavitation. It appears that the cause (or at least one of them) is that the diffuser has dislocated and pushed further into pump body. This in turn caused the inside of strainer basket to become warped. Strangely, I don't see the diffuser mounting screws and have no idea where they could have gone. The problem is that it's wedged in there good and can't be pulled out because the o-ring is pushed out on the top and bottom side. I've tried to push it back in but no luck. Any ideas on how this could even happen or suggestions on how to remove? I plan to order a new diffuser w/ o-ring. Once I have a replacement in hand, I can probably try cutting off the o-ring, and hopefully I can then force it out. Hopefully I can still mount the new diffuser in the existing backplate -- hard to tell if there's anythingt to thread into.

Jandy Pro Series Stealth SHPF1.0-2

 

[mas985]

Probably who ever serviced the pump in the past forgot to put them back. I would cut the o-ring and see if that works. If not, you might try heating the pump basket with a blower dryer so it expands a bit and see if you can loosen the diffuser. If you do get it removed, make sure where the diffuser seats is not deformed or damaged.

 

[DishoomX2]

Thanks for the suggestions. The pool was part of our new home build, which was completed in July 2017. For the first year and half, the pool contractor serviced the pool. Starting in late-2018, I personally maintained the pool chemistry, and no other service tech was called. It would be really strange if the diffuser hadn't been attached properly since initial install (or after the last tech serviced it). Do new pool pumps come assembled (motor+body), or do they need to be assembled during install? If already assembled, I don't know why any tech would have disassembled as part of normal service.

The cavitation/suction-side leak problem occurred in November 2020, and over the past several months, I've just kind of been living with it. Since the weather has started to warm up, it got me into really trying to solve this issue and get proper circulation before the hot summer months.

 

[mas985]

Yes, for residential pool pump, motors and wet ends are usually mated before sale. Many pumps do not have screws for the diffuser but this one definitely shows it in the schematic. So perhaps it was a manufacturing error or perhaps the pool service did forget to reinstall them. Do you ever remember the pump getting clogged or not performing properly. In order clear the impeller vanes, the tech would have had to remove the diffuser. The diffuser may have moved afterwards.

Note too that it probably isn't cavitation you are seeing. Air in the pump basket is due to an air leak. Cavitation is something completely different.

 

[DishoomX2]

It is very peculiar about the diffuser not being attached. Too much time had passed (+1.5yr) since a tech last serviced my pool. The pump would have been making noises for a long time, but this only started occurring within the last ~6 months. I'm not sure if a tech would have ever disassembled the pump since the pool is within a screen enclosure, and no large debris would have ever been sucked in. Sadly, we've probably only used the pool < 20 times since we've owned the house, so not very likely to be clogged with hair, etc.

So far in an attempt to resolve the air suction issue, I've changed all the 3-way valve o-rings (suction and pressure sides), drain plugs, the tail piece o-ring, and pump lid o-ring. The only other thing left would possibly failure in one of the glued pvc pieces either before the 3-way value or the glued tail piece that's then threaded to the pump inlet. Though pouring water over those joints resulted in no difference.

I then started thinking more about how the strainer basket was damaged and came across a video talking about pump impeller and diffuser issues.
Pump Impeller & Diffuser Issues, Pool Pump Not Priming

With all the air in the system, am I experiencing cavitation as a result of the detached diffuser? Sounds like gravel rattling, and periodic squealing sound. The impeller itself spins fine by hand with no noise. I don't think shaft seal is bad, as there's no leaking water anywhere.

 

[mas985]

The gravel sound is an indication of cavitation but you will not normally see cavitation bubbles as they occur near the impeller. If the shift of the diffuser created higher than normal suction, then perhaps there is some cavitation as well. If you have a clog in the suction lines, that can also cause both cavitation and air leaks.

 

[DishoomX2]

If anything there is less suction. It's hard to prime the pump once you turn it off to clean out strainer basket or clean the filter. There's a lot of air in the pump basket and bubbles coming out the return. I recently installed a new pressure guage on the filter housing, but the needle hardly moves...occassionaly bounces 1-2psi. It's a 2-speed pump. On low it sounds fine, barely audible w/ slight hum, and a big air bubble under the pump lid. When on high, it's pretty noisy. If I turn on the waterfall feature, the output is surging -- not a steady stream of water.

I'm thinking that what caused all this is that one day, the tail sweep on the pool cleaner got sucked into the cleaner itself. As a result, the pressure may have backed up and built up in the system, causing the diffuser to eventually blow out. My wife and daughter did say there was a loud noise one day as the pool cleaner was running. It's been a while but I don't recall the pump noise etc happening right after that mishap.

In any event, I suppose I need to fix this diffuser issue and then see what other problem(s) may remain.

Picture of my setup for reference.

 

[mas985]

Yes, that sounds like a severe clog. That can cause very high suction in the pump basket but reduces flow and filter pressure and reduced suction on the other side of the clog. That may have caused the diffuser to get sucked into the pump basket.

Also, why do you have the skimmer partially shut off? Normally, you would want most of the flow from the skimmer and very little from the MD.

 

[DishoomX2]

Yes, that sounds like a severe clog. That can cause very high suction in the pump basket but reduces flow and filter pressure and reduced suction on the other side of the clog. That may have caused the diffuser to get sucked into the pump basket.

Also, why do you have the skimmer partially shut off? Normally, you would want most of the flow from the skimmer and very little from the MD.

Good eye. That picture was taken several months ago. I must have been messing with the valves. Normally I just have the main drain side just opened slightly so that about 80%-90% of the intake is coming from the skimmer.

I should have mentioned that I'm a first-time pool owner, so I've been learning along the way. I'm willing to try DIY before I have to dig deeper into my wallet and call a pool service company. Though the last time I called a tech, I was told that all the noise is considered "normal" for Jandy and that my < 4yr old pump was just on it's way out.

 

[DishoomX2]

Update: I was able to remove the diffuser by cutting the o-ring. It turns out that the diffuser itself was not bad. There are supposed to be 2 o-rings on it, but there was only 1, so I wonder if this was a manufacturing defect. I understand that a pool service tech may have forgotten to screw the diffuser to the backplate; however there would be no reason to remove an o-ring. Although the replacement dfifuser kit came with screws, the threading in the backplate is practically non-existant. The screws just won't hold. What now? It's a really poor design on Jandy's part -- the screw holes in the diffuser are almost as large as the vanes, so I can't really use a larger screw and hope it will bite. Debating using epoxy to hold the screw in, but worried I may never be able to remove in the future. A replacement backplate is about $100.

For now, the diffuser is not screwed to the backplate -- it's mearly being held in place between the strainer basket, and impeller/backplate. Until I have a solution to secure, I hope it won't be forced back out into the pump body like the old one. The good news is that pump now primes easily without a suction leak or any surging. Only a quarter-size air bubble seen in the pump basket lid, which is what I was expecting.

 

[Vanhalen5150]

Update: I was able to remove the diffuser by cutting the o-ring. It turns out that the diffuser itself was not bad. There are supposed to be 2 o-rings on it, but there was only 1, so I wonder if this was a manufacturing defect. I understand that a pool service tech may have forgotten to screw the diffuser to the backplate; however there would be no reason to remove an o-ring. Although the replacement dfifuser kit came with screws, the threading in the backplate is practically non-existant. The screws just won't hold. What now? It's a really poor design on Jandy's part -- the screw holes in the diffuser are almost as large as the vanes, so I can't really use a larger screw and hope it will bite. Debating using epoxy to hold the screw in, but worried I may never be able to remove in the future. A replacement backplate is about $100.

For now, the diffuser is not screwed to the backplate -- it's mearly being held in place between the strainer basket, and impeller/backplate. Until I have a solution to secure, I hope it won't be forced back out into the pump body like the old one. The good news is that pump now primes easily without a suction leak or any surging. Only a quarter-size air bubble seen in the pump basket lid, which is what I was expecting.

View attachment 324145View attachment 324146

I’m having the same issues and the holes on the diffuser don’t line up with the housing plate on my Jandy stealth pump. No one has ever serviced my pump but me. No sin of a screw head no screw threads in the diffuser.

 

[davidwat]

I’m having the same issues and the holes on the diffuser don’t line up with the housing plate on my Jandy stealth pump. No one has ever serviced my pump but me. No sin of a screw head no screw threads in the diffuser.

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the holes on the diffuser don’t line up"

There are two orienting arrows

 

[davidwat]

Update: I was able to remove the diffuser by cutting the o-ring. It turns out that the diffuser itself was not bad. There are supposed to be 2 o-rings on it, but there was only 1, so I wonder if this was a manufacturing defect. I understand that a pool service tech may have forgotten to screw the diffuser to the backplate; however there would be no reason to remove an o-ring. Although the replacement dfifuser kit came with screws, the threading in the backplate is practically non-existant. The screws just won't hold. What now? It's a really poor design on Jandy's part -- the screw holes in the diffuser are almost as large as the vanes, so I can't really use a larger screw and hope it will bite. Debating using epoxy to hold the screw in, but worried I may never be able to remove in the future. A replacement backplate is about $100.

For now, the diffuser is not screwed to the backplate -- it's mearly being held in place between the strainer basket, and impeller/backplate. Until I have a solution to secure, I hope it won't be forced back out into the pump body like the old one. The good news is that pump now primes easily without a suction leak or any surging. Only a quarter-size air bubble seen in the pump basket lid, which is what I was expecting.

View attachment 324145View attachment 324146

Did you find an adequate solution for the stripped backplate threads? My diffuser came loose and broke in two pieces or perhaps broke in two pieces and then came loose.

 

[1poolman1]

Did you find an adequate solution for the stripped backplate threads? My diffuser came loose and broke in two pieces or perhaps broke in two pieces and then came loose.

Put a few strands of copper wire from "stranded" electrical wire into the holes to give the screws something to grab. You can cut thin strips from an aluminum can and do the same thing. Just hold the diffuser down while installing the screws. Don't overtighten. Once the diffuser is in place in the front of the pump it won't move.

 

[Nonyabiz]

Where does the second o-ring go?