Troubleshooting a Pool Pump: Why Won't My Hayward Pump Draw Water?

[DaveC426913]

Well, I'm stumped.
I've got this 1/4HP Hayward pump that simply will not draw water.

I've removed every factor in the system down to the bare minimum, replaced everything in the system that can be replaced and applied silicone lube to everything that can't.

I have a six foot length of new hose sunk into my pool that runs directly to the pump intake (bypassing the pool skimmer and filter).
I've greased the one O-ring on the intake. I've greased the O-ring between the basket and the pump.
I've pulled off the pump head, and inspected the manifold and impeller for debris.
I've checked that the impeller is spinning.
I've taken off the outflow, so it should shoot straight up into the air directly from the pump. When I turn it on, it shoots a half gallon of water up - the half gallon that I primed the basket with - and then barely dribbles after that.
There is literally only 6 inches of system left. From the pump intake to the pump output. It literally will not lift the 6 straight inches from the impeller to the outlet.The only thing left is to bypass the 6 foot length of hose that runs 2 feet up out of my pool and down 2 feet into the pump. I am sure that, if I opened the basket and poured water directly into the basket, the pump would shoot it out straight up. But if it's just that it can't draw a mere two feet of head from the pool, it's certainly not functioning.

I find the bearings on these things go yearly, and it's more cost-effective to simply buy a new pump every couple of years (~$250), but this year there's nothing wrong with the bearings.

Help.

 

[Drakkith]

Hmmm. The only thing I can think of from having to deal with my own pool pump is to make sure as much of the air is removed from the system prior to turning the pump on. But if you've primed the 'basket' (bucket-like thing with a clear lid?) then you should be okay I would think. I assume the impeller isn't damaged?

 

[DaveC426913]

Even though it's self-priming I expend a lot of effort priming it anyway, just to give it a boost. It's definitely not that.

I went all out and eliminated the last factor in the system. I took off all the hoses and dunked the head of the pump directly into the pool, so it had an infinite supply of water, and zero head.

Nothing.

And yet, the impeller is still impelling!

*don't try this at home. Nothing like holding a 1/4HP electrical device 2 inches above a giant pool of water...

 

[JBA]

It might be a good idea to check to see whether or not the pump shaft seal is leaking and allowing air to be drawn into the pump by placing your hand on the pump outlet to see if there is any air flow there. With the hose inlet under water, if the shaft seal is tight then you should not be able to feel any air discharge flow.

 

[DaveC426913]

That's got to be it. It's got to be the seal between the basket and the impeller manifold.

It's a funny thing.

When I screw the basket assembly back onto the pump, if I screw it tight, it does not align properly - the basket points down. So I have to back off the threading a half turn till the basket is vertical.

There's a "C-clip" around the throat (see diagram) with notches that are obviously designed to ensure the basket must be properly vertical, and that it won't unscrew spontaneously from vibration. So that makes sense.

But it's weird. Unscrewed that half turn, it's almost loose. I do not recall it being loose like that in the past.

Now, that being said, it should not matter to the water-tight seal. ("strainer O-ring" in above diagram). It is not an "end-seal" O-ring; it is a "girth seal" O-ring. This a crummy diagram, but it's just to show how the O-ring is around the girth, in the throat:

So it should be sealed as long as the male is in the throat of the female.

Still...

 

[Asymptotic]

I've checked that the impeller is spinning.

If it was pumping last year I don't see how it could be, but a symptom of blasting water from the pump casing, then nothing more, can happen if rotation is reversed.

 

[DaveC426913]

I put teflon tape on the threads, hoping to seal off any air ingress, and I greased the gasket around the manifold - but no joy.

A Video of the output just gurgling. While there may be a tiny bit of air, that's definitely water there. That's just six inches above the impeller.

Yet I can stick my thumb in the basket outlet and feel the impeller whizzing around.
Heck, I pulled the whole basket off so I can see the impeller turning.

No repair has had even the slightest impact on flow.

What's crazy is if I simply pour water on the exposed impeller, it shoots water straight up the outflow. But slap the manifold back together and nuthin'.

 

[Dullard]

I'm with Asymptotic - it sounds as if the pump is spinning backward. You may need to disassemble the pump to be sure of the impeller shape - the rotation direction is correct if the center of curvature (for any vane) is 'behind' the moving vane. If you're feeling more empirical, you could just reverse the motor (assuming that it's reversible). A 'wrong way' impeller still slings, but not efficiently enough to pull in much (any) new water.

Many general-purpose single-phase motors are 'reversible.' That always requires a wiring change (at the motor leads). Is there a prequel which includes some wiring work?

 

[DaveC426913]

I'm with Asymptotic - it sounds as if the pump is spinning backward.

No. You can see in the second video it's spinning counter-clockwise, which is the direction it should be spinning to shoot water out the outlet.

And it does shoot water out the outlet if I pour water directly on it. The water is obviously firing off the right edge of the impeller straight up the outlet.

 

[Dullard]

No. You can see in the second video it's spinning counter-clockwise, which is the direction it should be spinning to shoot water out the outlet.

And it does shoot water out the outlet if I pour water directly on it. The water is obviously firing off the right edge of the impeller straight up the outlet.

I didn't watch the video - sorry.

 

[Dullard]

No. You can see in the second video it's spinning counter-clockwise, which is the direction it should be spinning to shoot water out the outlet.

And it does shoot water out the outlet if I pour water directly on it. The water is obviously firing off the right edge of the impeller straight up the outlet.

OK, I watched the video. I can't really tell which way it's spinning (aliasing), but CCW is obviously the right direction.

 

[sophiecentaur]

Last ditch stand. Could the impeller be slipping on the shaft? A small amount of resistance / load stops it but it’s momentum carries it round enough to shift a small amount of water.?

 

[Asymptotic]

OK, I watched the video. I can't really tell which way it's spinning (aliasing), but CCW is obviously the right direction.

Ran it frame-by-frame through VLC, and the impeller appeared to turn CCW in the single frame observed before it blurred to unreadability.

 

[Asymptotic]

Last ditch stand. Could the impeller be slipping on the shaft? A small amount of resistance / load stops it but it’s momentum carries it round enough to shift a small amount of water.?

Had that happen to me once, although in that case it was a clear polycarbonate impeller, and signs of thermal distress were observable in the hub.

 

[DaveC426913]

Last ditch stand. Could the impeller be slipping on the shaft? A small amount of resistance / load stops it but it’s momentum carries it round enough to shift a small amount of water.?

I thought of that. I can apply pressure to it directly with my thumb and it seems pretty determined to keep spinning.

 

[DaveC426913]

OK. Problem solved. And of course it's me being foolish.

It turns out that the hose running out of the pool has a leak at its fitting:

Even though the hose was seated in the drain with teflon tape, the leak is several inches up, between the hose and the fitting.

I kept checking to ensure the overflow was full, and filled it frequently. So because the overflow wasn't draining of water, I had ruled it out as a source of a leak.

It sits in only 4 inches of water, enough to get a water lock, but the leak is up at the top of the fitting, so every time the overflow drained by just an inch, air was seeping in there. And that had not occurred to me.

I thought I had conclusively ruled out the hose as the problem when I short-circuited it directly from the pool - bypassing this connection completely. But I guess that test wasn't as conclusive as I thought.

Thanks guys for all your assistance. I never would have kept at it if you guys hadn't been filling me full of ideas to try.

 

[sophiecentaur]

PF (at least me) loves this sort of brain teaser. Glad you have closure.
I was about to suggest that the motor was running in reverse - I was that desperate for an answer.
Anyway - well done.

 

[DaveC426913]

Several good things have come out of this:

1] I have learned the value of keeping the seals lubed.

2] By adding a threaded union fitting under the overflow basket, I can now detach the hose from the overflow basket and dunk it right into the pool.

3] I just figured out that I don't need to run fresh water into the pool to keep the overflow filled (to preserve a water lock). Running fresh water means it needs to be babysat. (Too often have I forgotten the water was on.) Instead of fresh water, I simply run my sump pump from the pool into the overflow. Now I can circulate the whole system, including the filter without having to fill the pool to operating level.

4] I'm much more confident now that I can disassemble and maintain the whole system. (I mean, I was good before, but this was a real win. Solved many problems that have plagued my system over the years.)

 

[austinace]

Well, I'm stumped.
I've got this 1/4HP Hayward pump that simply will not draw water.

I've removed every factor in the system down to the bare minimum, replaced everything in the system that can be replaced and applied silicone lube to everything that can't.

I have a six foot length of new hose sunk into my pool that runs directly to the pump intake (bypassing the pool skimmer and filter).
I've greased the one O-ring on the intake. I've greased the O-ring between the basket and the pump.
I've pulled off the pump head, and inspected the manifold and impeller for debris.
I've checked that the impeller is spinning.
I've taken off the outflow, so it should shoot straight up into the air directly from the pump. When I turn it on, it shoots a half gallon of water up - the half gallon that I primed the basket with - and then barely dribbles after that.
There is literally only 6 inches of system left. From the pump intake to the pump output. It literally will not lift the 6 straight inches from the impeller to the outlet.The only thing left is to bypass the 6 foot length of hose that runs 2 feet up out of my pool and down 2 feet into the pump. I am sure that, if I opened the basket and poured water directly into the basket, the pump would shoot it out straight up. But if it's just that it can't draw a mere two feet of head from the pool, it's certainly not functioning.

I find the bearings on these things go yearly, and it's more cost-effective to simply buy a new pump every couple of years (~$250), but this year there's nothing wrong with the bearings.

Help.

A centrifugal pump does not suck water into the impeller. The impeller must be flooded and no air in the feed pipe or hose in this case. A hose has a large pressure drop. Better to use pipe with no elbows if possible. For example, a well pump has to have a check valve or foot valve at the bottom of the well to keep the inlet pipe full or the pump will not push water.

 

[DaveC426913]

A centrifugal pump does not suck water into the impeller. The impeller must be flooded and no air in the feed pipe or hose in this case. A hose has a large pressure drop. Better to use pipe with no elbows if possible. For example, a well pump has to have a check valve or foot valve at the bottom of the well to keep the inlet pipe full or the pump will not push water.

These pumps are self-priming.

 

[sophiecentaur]

These pumps are self-priming.

Any pool owner worth his salt would use a much more interesting form of pump.

Or see this link for ideas.