Suction side air leak

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PoolStored

PoolStored

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TFP Guide
Jun 24, 2021
8,198
Ashtabula, OH
Pool Size
30000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-60
JamesW said:
Try pushing water into the pump from a skimmer. That way the suction is under pressure and a leak will be obvious.

Rig up a garden hose into the skimmer hole with adaptors and push water through the system.

Make sure that the water can flow through the system because city water pressure can be too much for the equipment if the water is blocked

Or, just pressurize the system to about 10 psi to see if the leak becomes obvious.
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James, you are a genius. I have a REEEAAALLY slow suction side leak, tried shaving cream, nada, rebuilt 3 unions and 2 valves, TWICE and I can't find it to save my soul. Just bought the parts to build a pressurization rig with thru-hole plug. Was going to use it to pressurize the inbound from the unions to the the pump union since it is removable.

Couldn't figure out how I was going to do the lines to the pool. I'm sure I would have figured it out, but you saved me the trouble. Thanks!

Plumb 3.jpg
 
1poolman1 said:
A leaking shaft seal will cause a suction leak. I see it quite regularly. Regardless, it needs to be replaced before the motor is damaged.
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So, you are saying rebuild the pump? The shaft seal is way after the suction side. Happy to rebuild the pump, just didn't think the shaft seal could lead to air in the pump cover. Confirm? If so, learn something new every day! Thank you!

Leak is SUUUUUUPPPPPPEEEER slow.
 
PoolStored said:
@1poolman1 got the pump apart. Drive shaft had/has some rust. Hit it with 600 grit. Do you think it will work, or with pits it will leak?

View attachment 405473
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The bellows portion of a 200 seal needs to be able to "seal" on the shaft of the motor with the small rubber ring against the impeller. You can see where that was as there is clearly a line where the rust stops. I have made a practice of putting a very-light film of silicone RTV in that area of the motor shaft when I see corrosion like this. DO NOT get it on the sealing surface of either the bellows or ceramic. Pay close attention to how the seal is assembled. I don't know your experience, but many times see pool owners put them in backwards.

A light coat of silicone on the rubber cup on the ceramic will aid in installation and sealing of that part in the sealplate. Place the ceramic over the cup and use the handle of a screwdriver to push it into place. If it wants to come out a little don't worry as the impeller will force it back as it is tightened.

Haven't got a clue as to how some of the stuff that happens with pool equipment happens. How can a bad shaft seal in what should be the pressure area of a pump cause a suction leak? Don't know, just know that it can as I have seen it literally hundreds of times in 33 years. Is that your only issue? Don't know, but it is one of them. I always tell customers that I found the first problem. Are there more? Won't know until this is repaired.
 
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1poolman1 said:
DO NOT get it on the sealing surface of either the bellows or ceramic.
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1poolman1 said:
Thin coat, just make it shiny. Then place the seal on the shaft and allow it to contact the uncured silicone by slightly compressing the spring.
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Not sure I understand how to do both.

I will put the ceramic in the housing, then mount. Put rtv on shaft. Slide on bellows. When I slide it on, won’t it get on the ceramic and the bellows surface by being pushed back by bellows?
 
Not if you are careful. Very light coat. The only part of the seal that will contact the motor shaft is the end against the impeller. You can see that if you look at where the rust stops on the shaft now. You could put the RTV on that end of the bellows instead. Works either way. I've been doing it on the shaft so long I forget it can be done another way. Just habit, I guess.
 
@1poolman1 Stupid is as Stupid does. Ugh. Replaced all to perfection Fit great. Started the pump up and smelt burning ceramic. I forgot to fill the pump with water. Turned if off immediately (maybe total 10 seconds of run time). Filled it up and started again. Seems to be working. Not sure if it fixed the suction side leak or not. We will see, need to let it run.

The question is, do you think I fried the seal? Luckily I ordered a go kit, and a spare seal, so if I did fry it, I have another and is easy swap. Let me know your thoughts. Thanks!
 
PoolStored said:
@1poolman1 Stupid is as Stupid does. Ugh. Replaced all to perfection Fit great. Started the pump up and smelt burning ceramic. I forgot to fill the pump with water. Turned if off immediately (maybe total 10 seconds of run time). Filled it up and started again. Seems to be working. Not sure if it fixed the suction side leak or not. We will see, need to let it run.

The question is, do you think I fried the seal? Luckily I ordered a go kit, and a spare seal, so if I did fry it, I have another and is easy swap. Let me know your thoughts. Thanks!
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You may have shortened the life a bit. Just watch for leaks. Since you have another it might be best to go ahead and replace since they are relatively easy. Seals are the motor's only protection from the water and VSP motors are very expensive.
Seals are also a wear item. Pump manufacturers used to recommend replacement every 5 years. Century motor company used to say the same. Don't know anyone that does that. Since VSPs run slower, seals may last longer.
 
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