Multiple Polaris booster motor failures - Need advice

[DeadAquaRite]

I'm about to replace my Polaris motor for the second time in 9 years. The first lasted 6yrs, the second a week shy of 3yrs. Both were caused by failed front bearings. I'm hoping to reduce that and/or reduce the expense, hence this post.

The first time I purchased new bearings. But after snapping off 2 of the 4 long bolts, I shelved the bearings and ordered a new motor.

This time I decided to try bearing replacement again. The long bolts came out, and the rear plate/bearing was easy on/off. The front bearing removal was a total failure, leading to a new motor. The problems I experienced were:

- Front plate (aluminum) badly corroded by salt.
- Bearing retainer plate screw corroded beyond removal. Head stripped out inside (flat) and out (hex). This meant removing the bearing with the front plate as a unit.
- Front bearing retainer plate failed (bent) while pressing off plate/bearing assembly. Bearing remained on shaft.

At this point, I gave up again. But the disassembly yielded info. Most notably that the space between the bearing and plate was filled with salt. Combined with the plate corrosion, it's obviously caused by salt water. I cannot see any visible leaking when operating or idle. And the slinger disk is in place and looks good. but obviously little drops of water are walking down the shaft and into the motor housing, killing the front bearing.

Any suggestions on prevention? I'm currently thinking about a slight forward tilt, multiple slinger discs, and maybe even manufacturing some manner of shaft seal on the motor front.

Anyone out there do an annual or semi-annual rebuild as a preventative?

 

[JoelFitz]

A few issues to take into consideration. Booster pumps aren't self priming therefor need water pushed to them.

1.) What controls your pumps? Automation or time clocks?
2.) How is the pump plumbed into the system? Soft tubes or rigid PVC?
3.) How long do you run the cleaner per day?

 

[DeadAquaRite]

Loss of prime doesn't seem to be an issue anywhere in the system.
The booster is being pressure fed from a T just past the salt cell.

1) Time clocks. Booster will not run w/o primary running.
2) 1.5" rigid until the last 14-18", then soft (3/4 or 1")
3) 4 hrs in season, 2 hours fringe months, none in winter.

 

[JoelFitz]

Wow. If I was called to your house and found that I'd find it hard to believe the pump wasn't leaking. I don't think that's salt though. Is the pump bonded? It almost looks to be a bad case of electrolysis. If I was a betting man though I'd have to blame it on a seal leak.

 

[DeadAquaRite]

I agree with your assessment, but I can't find any obvious evidence of water leakage besides the corrosion. It sits on a concrete slab, and the slab is dry except when it shouldn't be (rain). I think I'm just dealing with a very slow leak, possibly one that only happens when the motor is running. Water trickles down the shaft and is flung into/onto the motor head, where it evaporates.

Yes, it's bonded. But that's a good point. I'll validate earth ground with a meter. And the pump seals were all replaced with the last motor. And they will be again with this one.

That is definitely salt water corrosion, seen it many times at my inlaws house in Fla. With an aluminum and steel interface, the aluminum acts like a sacrificial anode. Plus, there was probably a half teaspoon of salt caked in the bearing well between the bearing and the front plate.

For perspective, that's the rear of the shaft above (bearing is new) As you can see it only has minimal surface rust. The back place looks good as new, as do the windings and the wiring.

 

[JoelFitz]

Well actually what you see is calcium that has precipitated out of the water due to the heat of the motor. If it was salt you'd see more corrosion of the harder metals (IMO), it could also be a combination of the two. You can try a zinc anode or similar device to see if that helps but my money is still on a wicking of water down the shaft.

GL!

 

[DeadAquaRite]

So my new polaris booster motor arrived today. I ordered this:
Amazon.com : Zodiac P61 3/4-HP, 60-Hertz Threaded Shaft Motor Replacement : Swimming Pool Pump Parts : Patio, Lawn Garden
Note: Amazon currently lists this motor at $218. I paid $153 just three days ago.

But received this:
ecatalog | ASB625 - 0.75 HP - ODP - 3450 RPM


I wasn't surprised that it wasn't exactly as depicted, or even the brand listed, as I did order a cheap generic OEM replacement motor. But upon inspection, things got interesting.

On the motor body was was a big, prominent shield label that read "AQUA shield". Assuming it was all just marketing started inspecting closer. The motor wasn't Zodiac, but US Motor. And the part wasn't B625, but "ASB625". The start cap wasn't under a metal side bulge, but under a plastic aft cover. The underbody vents are gone, allowing only linear airflow. And then I spotted something that made me very happy. The front plate at the shaft has a machined recess, and in that recess is a shaft seal. Not just a piece of rubber, but an actual shaft seal.

Obviously, the volute is getting a rebuild. But I am excited that this motor appears to have integrated protections against front shaft bearing failure resulting from leakage.

 

[gwegan]

Frankly I would skip installing the new pump send it back and buy a robot. They do just as good a job and cost much less to operate. When it dies in ten years you can choose a whole new one and not have to worry about what system you have.

 

[DeadAquaRite]

Frankly I would skip installing the new pump send it back and buy a robot. They do just as good a job and cost much less to operate. When it dies in ten years you can choose a whole new one and not have to worry about what system you have.

I don't understand your post. I have a Polaris 280. Your signature indicates a Polaris 360, which is very similar. What are you suggesting? Link?

 

[Pool Clown]

Where do you live? I don't think the corrosion on the backing plate is from a (seal) leak. Otherwise, how would it get back there without shorting out the motor on the way? And it would do so long before wrecking the bearings. It would have to leak enough for you to at least see water on the pad, and even then...

The corrosion, i agree, isn't salt from the pool. Without knowing where you lived, i would almost guess you lived near the coast.

Your first failure after 6 years while isn't the longest I've seen, certainly isn't surprising to see. 3 years though is something to perhaps take a second look at.

I'm assuming that the shaft seal was replaced both times?

 

[JoelFitz]

Those two pumps look different as far as the threaded shaft goes. DO yourself a favor and try to thread the impeller on the new pump before you get too far into it.

 

[DeadAquaRite]

Those two pumps look different as far as the threaded shaft goes. DO yourself a favor and try to thread the impeller on the new pump before you get too far into it.

I didn't even notice that in the picture. The actual shaft I received is identical to the one it's replacing. Although when inspecting it some more it appears that the front shaft seal is installed backward (spring out). That would be correct for an oil seal, but to keep outside liquids out, it should have been installed wiper out.

I did a little preventative maint on this one. I pulled all the threaded components and oiled them before reassembly. Maybe the next disassembly won't be so difficult.

Where do you live? I don't think he corrosion on the backing plate is from a (seal) leak. Otherwise, how would it get back there without shorting out the motor on the way? And it would do so long before wrecking the bearings. It would have to leak enough for you to at least see water on the pad and even then...

The corrosion, i agree, isn't salt from the pool. Without knowing where you lived, i would almost guess you lived near the coast.

Your first failure after 6 years while isn't the longest I've seen, certainly isn't surprising to see. 3 years though is something to perhaps take a second look at.

I'm assuming that the shaft seal was replaced both times?

I live 30 mi due south of Atlanta, far from the coast. And I don't get that type of corrosion on any other equipment, including the filter pump, which is still going strong. But yes, it looks exactly like the salt corrosion you would see at the coast. That is why I assumed it was salt corrosion.

The picture is of both sides of the front plate. The back plate looks good/normal. IMO, it's clearly a shaft seal leak problem.

Yes, the entire got new seals, including the shaft. And it will be rebuilt again this time.

 

[Pool Clown]

Hmm, and you never got any water on the pad under the pump? That thing has got corrosion in places that wouldn't get wet even if there wasn't a seal in the pump! I mean, you got corrosion outside of the bracket!

Do you hose off the equipment periodically? But this is the only motor this happens to, right?

Weird...

Is that an A.O. Smith? Or a Magnatek? If it isn't, maybe poor materials? Once in a while, i see corrosion this bad, but never check to see what kind (manufacturer) of motor it is. I just change the thing, and move on...

The bracket should have a tiny hole in it and it should face down. This is so any water leaking from the shaft seal can drain out of the bracket, on to the ground for you to see. As you are reassembling, check to make sure that the hole is clear, and of course, facing down.

I imagine you will be keeping an eye on this one. See if it begins to corrode, and if it starts in a particular area, or if it starts all over. If it starts all over, that may indicate environment compared to a leak .

 

[DeadAquaRite]

Nope, No water on the pad unless it has been raining.

I don't hose it off, but it does sit in the open (shaded 90%) so it get's rained upon. And this is the only item, including the main pump, that gets corrosion. And like I said, the rear plate of this one looks fine.

The hole was down. I didn't consider that last time, but figured it out after I got it all back together and noticed the hole on top (@$#%!). It's about 3/16", with no apparent blockages.

Dead motor is labeled a Century 1081. Googling, it appears that is an AO Smith motor.

As this one is only affected on the front plate, and where the housing meets the front plate, I'm leaning against environmental.

 

[DeadAquaRite]

Ok, so it's installed and functional. And it has a slow leak...

Apparently, it's leaking between the shaft seal and the volute housing.

Since it looks like I need a new volute housing anyway, any reason not to try an improvised fix? I'm thinking of driving out the seal, putting down a bed of JB weld, and driving the seal back in.

Thoughts?

 

[gwegan]

I'm suggesting you scrap using a pump powered vacum and go to an electric robot. They are much less expensive to operate and do as good or better job. Once a week you plug it in throw it in the pool and it cleans the pool. No pumps. And they cost much less to operate.

When my 360 dies I'll probably switch to a robot.

 

[Pool Clown]

A new bracket isn't that expensive. I'm just as frugal as the next guy, but when you compare the cost of the new part compared to what you think your time is worth (to fix the part which may or may not work) it's a no brain-er. Unless of course your'e retired, and have the time to tinker with it. Go for it. Cracks in the seal section are problematic due to expansion (from the seal being driven in), heat, vibration, etc.

Keep us posted. If you can get the patch on the water side, I think that would be your best bet. That way, you're "pushing" the patch through the crack. Rather than a patch on the outside that would be getting pushed off the crack.

 

[DeadAquaRite]

A new bracket isn't that expensive. I'm just as frugal as the next guy, but when you compare the cost of the new part compared to what you think your time is worth (to fix the part which may or may not work) it's a no brain-er. Unless of course your'e retired, and have the time to tinker with it. Go for it. Cracks in the seal section are problematic due to expansion (from the seal being driven in), heat, vibration, etc.

I'm a tinker anyway. The way I see it my choices are:

A. Order a new housing and seal set
B. Try this and if it fails I order a new housing and seal.

And if it works, then I run it until it dies and know I'm in for a new housing next time.

If you can get the patch on the water side, I think that would be your best bet. That way, you're "pushing" the patch through the crack. Rather than a patch on the outside that would be getting pushed off the crack.

That was my plan. Put a nice bead on the water side, then re-seat the seal in it. A lot like a sink trap being set in the bottom of a sink.

I'm suggesting you scrap using a pump powered vacum and go to an electric robot. They are much less expensive to operate and do as good or better job. Once a week you plug it in throw it in the pool and it cleans the pool. No pumps. And they cost much less to operate. When my 360 dies I'll probably switch to a robot.

I may do that next go around. For now, if I can get out of this for the cost of a motor I'm happy.

 

[msumoose]

If this is a older PB4 booster, the shaft seal has a metal cup that sits in the motor side of the volute, and a spring loaded one on the impeller. For a while, Polaris OEM seals came with the instruction to put a bead of silicone in the volute where the cup sits. Some of the generic shaft seals lack this instruction. I ALWAYS do this, but you have to be careful to not get any sealant on the ceramic disk. I have found it helps my callback rate on these pumps.

Nowadays, I have a source for knockoff PB4 pumps that cost me what a motor does. I just replace the whole thing, takes 20 minutes...

 

[DeadAquaRite]

It is, Thanks. I definitely did not do that last time. I was debating silicone or epoxy, sounds like you just made my decision easy.