Finding leaks on a pool filter pump

9326yssh

Have 2 self priming pool pumps that will not start suction on less water is added manually I assume that is air getting into the suction side of the pump but could not find exactly where any ideas how to find those kind of leaks

Thank you all, learning a lot here

Intplm.

An air test performed separately on each line is a good start.

If the lines and pumps are below the water line, there should be no need to prime the pumps manually. If they are above or even with the water line, you would need to prime them to get them working. If there is a leak at the farthest point of the pipe and the pipe is below the water line, then you should be able to prime both ways. The prime should hold. Just because the pumps won't prime, self-priming doesn't necessarily mean that there is a leak.

Jamie Hall

I may be confused… a self-priming centrifugal is only self-priming after an initial use. It won't just sit there and prime itself from dry. There are a few types of pumps which are truly self-priming, but I doubt that that's what you have (piston pumps, some types of flexible rotor pumps).

If a self-priming pump won't hold it's prime, there is a leak in the pump itself. Commonly the shaft seal.

If it's not a self-priming design, but se up to be self-priming once primed once (many centrifugal setups, jet pumps, the like), then there is a leak in suction line or the foot vavle is not holding.

Larry Weingarten

Hi, These pumps often have a filter basket on the inlet. You fill that basket with water and securely replace the cover. That cover can be a source of air leaks. This should give the pump enough to get things moving. 🤠

Yours, Larry

ps, from your description, it sounds like they pump, but then after sitting a while, no longer pump. If so, there is an air leak someplace that's draining the pumps. Pictures of the pumps and surrounding piping would be useful.

9326yssh

See attached

photo I took while on the job I hope that helps and to clarify things a little bit the two pumps are on two different locations and they have worked fine at time of installation but now few years later it's not priming anymore there is no water leak that I have seen on the pumps

Possible the pump just wear out,? It's that once primed they work properly not sure I want to replace pump just for that

9326yssh

Photo of pump model

hot_rod

looks like a grey pvc union on the suction, check the o ring in that

The piping between the pump and pool could have a crack

Yes, the impeller vanes can wear after time and performance drops off

9326yssh

How do i find leaks on a pipe that's in vacuum,? under pressure I would see leaking or spray bubbles but what's the process here on the suction side

Larry Weingarten

Hi, With that clear cover on the pump's filter basket, I'd start by getting things running and see if all of the air clears itself, or if air keeps coming into the basket. That might help you to get an idea if there is a leak and where the leak is, upstream of the pump or not. Then, with pump off, I'd look at every joint to see if it's wet. It seems even a leak downstream of the pump could cause this problem as it will allow all of the water above the level of the pool to drain down. I suppose if the leak won't show itself, a bubble-tight spring check valve on the pump inlet side, as close to the pool as you can get it could fix this.

Yours, Larry

ps, I'd like to second @Jamie Hall 's idea of a leak at the pump's shaft seals. I'd look closely at those places.

mattmia2

so the 2 ways the find manifold vacuum leaks in an engine are by spraying oil or carb cleaner on the suspected leak, the oil or car cleaner temporarily seals it and the performance problem goes away for a moment. might be able to do that with water or glycerin or something. the other way is to blow artificial smoke in to the manifold and look for the smoke coming out. not sure if your leak is big enough for either of these.

ChrisJ

I'd post here and get some info from people who deal with this all of the time.

https://www.troublefreepool.com/forums/pumps-filters-and-plumbing.11/

Personally, I'd expect there to be check valves in such a system, but I honestly have no idea.

9326yssh

Thanks Larry I will start the check up as you mentioned and will try that oil idea from Mattmia2 that smoke idea I'm not sure how to produce

maybe a thermometer can help me out here as well?

The system already have check valves in place

Larry Weingarten

Hi, You already have check valves… This is interesting info and suggests they don't work. Are they swing checks? I'd like to see PVC spring checks with rubber seals. If you have those already, good chance chlorine in the water has messed up the rubber. Are the checks threaded in with a union or some other way to remove them? This might be a case where more than one thing has failed. Good chance you have both air leaks and failed checks.

Yours, Larry

ChrisJ

https://forum.heatinghelp.com/discussion/comment/1858013#Comment_1858013

The return back to the pool can't have a check so that's a way for air to get in.