Pump failing to prime - clogged suction line?

Postby **Henry_R** » Mon 06 Jul, 2009 00:03

Hello, I'm part of a maintenance commitee of a small HOA. We have a community pool that we are hoping to maintain ourselves. We've managed to turn the swamp into a blue pool with the help of this forum.
Here's the thread:
viewtopic.php?f=4&t=8541

Now onto the question: what causes a working pump to suddenly fail to prime?

After some problems with the HOA president ordering the pump not be used (please see thread above for details) it was decided to use it or have a green pool. It was working ok, we have a timer and it was set to run from about 2pm to 8pm. I realise this is not much but it was a compromise.

Anyway, last Monday the issue began. I arrived home to discover the pool pump on, but there was no suction and the pump was dry. I promtly turned it off. I put water in the strainer and tried again. It sucked in the water and ran dry again. SO, I suspected a clogged suction line. I ran the hose down the suction line until I could see bubbles coming through the skimmer. This seemed to confirm my thought that there was a clog. I filled the strainer again. Turned on the pump and it began to prime and worked fine for the rest of the evening. I didn't change the timer setting and it turned on again Tuesday afternoon.

The HOA president found it dry again and she shut it off. She also doesn't want it run on a schedule until we have it looked at. I put water in the strainer and followed startup procedures and it wouldn't prime as before. After again putting the hose down the suction line I seemed to have cleared it. It primed the second time I tried agin. So since then I have to manually turn on the pump to be sure it's priming ok.

On Saturday it took me another 30 minute session of clearing the line before I could get it to prime.
But again once it got going it worked just fine.

What gives? Why does it keep failing to prime? Is this a suction line issue I'm chasing or something else?
The main drain is not working (again see thread above) so the skimmer is the only intake for the pump.

The motor has developed a whining sound (from going dry twice?) when it's on, but is otherwise working normally except this issue of the pump not priming.

The only other information I can give is that there is a leak on the seal at the motor/pump connection.
There is a stainless steel band with a knob to tighten the band but there is water leaking from the bottom of the band. It began as a small drip (think leaky faucet) and now is constant when the motor is on.
I'm not sure if this is related to the issue at hand but I'm not ruling anything out.

Also, due to the time of year and extended heat wave(Houston, TX) no pool service will call us back so we have to go it alone for now. We have called several services and they all seem too busy to take on a new pool.

Postby **Denali** » Mon 06 Jul, 2009 01:57

Hello again Henry,

From your description what you have is a leaking pump seal and the bearings in the motor starting to go. Those problems may have been caused by the pump running dry or it could be the leaking seal lead to the pump running dry. Either way you'll have to get the pump seal replaced and probably have the bearings replaced also.

A clog in the suction line could have caused the pump to run dry and thus caused the other problems. There is a tool called a Drain King you can get at home depot. It attaches to the end of a garden hose. You slide it into the opening at the skimmer and turn on the hose. Any clog in the suction line will be pushed toward the pump and usually end up in the pump basket.

When a pump seal starts to leak priming the pump becomes more difficult. The seal is the barrier between the wet end of the pump and the motor. So when it's leaking the motor gets water in it and the bearings are often the first to go (the whining noise). I know money is tight there but running the pump with a leaking seal will cause problems with the motor.

Just had another thought on this. The clamp you mention on the pump holds the whole assembly together. There is an oring in there that may have been damaged when the pump ran dry. The drip, drip leak you mentioned could be from that o-ring or from the pump seal. Either way you have to have it fixed in order to run the pump.

Postby **Henry_R** » Mon 06 Jul, 2009 09:45

I was told about the seal at the pool supply store when I described the drip. Since we haven't been able to get someone to come out here I've just been watching it and leaving it be. He didn't state that the seal would let water into the motor though and I didn't think of it either.

The idea of water in the motor is distressing. How complex is this to repair vs just replacing it?

We have limited funds, but we were considering fixing everything including the pump/motor and filter at some point when we fix the rest of the pool. The hope was to go through the end of the season and gather the funds. We hope to fix the main drain and restore the pool to like-new condition as possible too.

This sorta puts a damper on things. RATS!

In the mean time WHAT do we do to keep the pool clean? As I stated before we've been encountering resistance from pool services to even agree to come out. :evil:

SO the problem isn't likely to be fixed very soon. The one pool guy my neighbor called stood us up and never callled back. :evil:

The property manager says all his pool services are having issues keeping up with their current pools due to the excessive heat wave (it's been over 96 for several weeks with 100+ heat index)
and are not wanting to take on more.

We'd been using trichlor tabs in the feeder and this was going ok. Are we going to have to shock it every other day? It's been so hot even overnight that the chlorine measurement was 10 on Sat. evening and almost zero yesterday morning.

elf · Postby **elf** » Mon 06 Jul, 2009 14:28

it could be unpriming when shutting off, when the pump basket O-ring gets dry or is bad. You can take it off & buy a new one, they are normally under $10. Or lube the O-ring up nice & good add water to pump pot & see if it happens again.

Postby **Henry_R** » Mon 06 Jul, 2009 16:36

The o-ring on the stainer is worn. One of the first things I noticed was it being in need
of eventual replacement. I don't think it's bad though. If the o-ring was bad would it
still have suction and air escaping noise while opening it? The pump gurgles when
the power is cut off though. Is this a sign it's unpriming?

In any event someone is supposed to come this week hopefully and check this out thoroughly.

As I said this is an HOA community pool and we're doing this work ourselves for various reasons
including costs. We had a pool service and they were leaving the gate to the pool area open
creating a liability. They claimed they weren't given a key. They were fired and at the time the
pool was so green that the pool companies wanted to bid to do way more than was needed
and charge $$$$ for the work including draining the pool. We dumped some chlorine shock
in there at the beginning of June and started using the pump and shocking weekly. It's mostly
been blue since. Our attempts to find decent pool service have met with problems so we've
continued to maintain it ourselves.

Now this problem comes up and we're desperate to have professional help and still cannot get
it. In the mean time we have no choice but to maintain it ourselves, for better or worse.

We don't want to create more problems though by not having a serious problem checked.
If the shaft seal on the motor is going or gone we cannot risk further damage to the motor.
Not to mention our being liable to fix it if it breaks further now that we have a suspicion of a
shaft seal failure. We have to wait and see what a pro says. For better or worse we have to
wait.

elf · Postby **elf** » Mon 06 Jul, 2009 20:30

you hearing a sound when pump shuts off tells you the pump is unpriming.

you could lube the o-ring to pump basket which you say is worn & see if this helps by testing it after doing.

if anything beyond/behind pump is bad like seals you would have a water leak and the ground would be wet.
you would see water coming out the back of pump.

Postby **Henry_R** » Mon 06 Jul, 2009 21:56

That is what is happening. There is a leak at the seal between pump and motor. The stainless steel band that has a knob to tighten it down is where it leaks. From the bottom obviously. It began as a small drip and as of last week began to become like a faucet. This wasn't discovered though until Friday when there was more water than before. I think the failure to prime and the leak are connected though.
There is an o-ring in there and the motor shaft seal. The latter is what is likely leaking.

We have someone coming tomorrow morning hopefully to work on it as well. We'll see what they want to charge. I'm not sure what funds we have so we're going to have to be cautious.

Hopefully it won't cost more than $200-300 since a new pump and motor could be had for about $400 and would make it almost worth just getting a new one. We don't really want to do that though since at some point we'd like to replace the whole filter/pump/motor at once when we can get them all at the same time and pay one price for installation.

Postby **Henry_R** » Wed 08 Jul, 2009 19:42

We had someone out yesterday and got a bid for replacement of the seals. The man said the bearings are going on the motor, but it's not going to go out soon in his estimation. As long as we can live with the "noise factor" he thought it would last a while longer. We have no choice but run the pump a few hours per day to keep the water clear. So far so good.

My next question: in lieu of having the bearings replaced is there such a thing as a thermal overload breaker that can be wired in series with the wiring to the motor? The motor doesn't have a breaker built in as far as I can see and I don't think there is a circuit breaker near the pool. There is a switch that resembles a light switch that cuts off both the timer and hence the motor. I doubt this is a circuit breaker though.

We currently have neither the money for a new motor and have not yet obtained a bid on the bearings being replaced, but I'm guessing it's not going to be cheap either. It seems to me a thermal cutoff would be at least protection from the motor overheating and burning outright. Ideas?

We really need this motor to work through the end of the season. Once the off-season comes we might be able to get this whole pool fixed including replacing the motor/pump/filter.

Postby **Denali** » Wed 08 Jul, 2009 21:16

Henry_R wrote:We had someone out yesterday and got a bid for replacement of the seals. The man said the bearings are going on the motor, but it's not going to go out soon in his estimation. As long as we can live with the "noise factor" he thought it would last a while longer. We have no choice but run the pump a few hours per day to keep the water clear. So far so good.

My next question: in lieu of having the bearings replaced is there such a thing as a thermal overload breaker that can be wired in series with the wiring to the motor? The motor doesn't have a breaker built in as far as I can see and I don't think there is a circuit breaker near the pool. There is a switch that resembles a light switch that cuts off both the timer and hence the motor. I doubt this is a circuit breaker though.

We currently have neither the money for a new motor and have not yet obtained a bid on the bearings being replaced, but I'm guessing it's not going to be cheap either. It seems to me a thermal cutoff would be at least protection from the motor overheating and burning outright. Ideas?

We really need this motor to work through the end of the season. Once the off-season comes we might be able to get this whole pool fixed including replacing the motor/pump/filter.

Hi Henry,

The motor itself has thermal protection built in. If it overheats it shuts down. What you want to avoid until the seal is replaced is running the pump dry. If it loses prime the water that remains in the pump heats up and starts to melt things. That is probably what happened to your seal.

So if you are running the pump a few hours a day and can check on it to make sure it hasn't lost prime you're ok.

He is probably right about the bearings. The noise can get pretty bad over time but if the seal gets fixed and there is no water leaking you should be fine.

Postby **Henry_R** » Wed 08 Jul, 2009 22:04

After I posted the question I found the picture I'd taken of the motor where it clearly states "thermally protected". :oops:

You've replied before I did.

What it doesn't have is a resetable breaker for the fuse though. Once it trips the motor is a boat anchor. Or am I wrong on this?
Is it possible to fix the motor after the thermal cutout trips?

Thanks for the info about the water melting things. That's interesting.

We've had problems in the past with the water level getting too low and
the pump gurgling and the motor screaming. We were told by our then
HOA president that the low water level causes the pump to "suck air" and
lose prime which heats up the bearings. Would it be safe to suspect this
as the beginning of the bearings being damaged and the seal too? (Event zero?)

What's interesting is that the motor serial number says O80L which dates
to Dec 2005 as a mfg date. If so then the motor seals are supposed to be
resistant to damage. We don't have records that show the motor water
replaced though which is the enigma.

I've been only running the pump long enough to cycle the water.
4 hours at most per day so as not to have longer term problems.
I've had to manually add water to the strainer basket each time
I power on too. It won't prime after being off unless I do.
This is why it was dry when set to turn on automatically.

There is a discinct sound of escaping air (a hissing sound) around
the motor even when the pump has been off for a while. Is this
related to the seal being bad? Air in the system bleeding off through
the bad seal?

Postby **Denali** » Wed 08 Jul, 2009 23:32

Henry_R wrote:After I posted the question I found the picture I'd taken of the motor where it clearly states "thermally protected". You've replied before I did. What it doesn't have is a resetable breaker for the fuse though. Once it trips the motor is a boat anchor. Or am I wrong on this?
Is it possible to fix the motor after the thermal cutout trips?
After it shuts down, it cools off and will come back on again. It shuts itself off before there is any damage to the motor
Thanks for the info about the water melting things. That's interesting.
What you will normally see is a pump basket that has shrunken up and is distorted.
We've had problems in the past with the water level getting too low and
the pump gurgling and the motor screaming. We were told by our then
HOA president that the low water level causes the pump to "suck air" and
lose prime which heats up the bearings. Would it be safe to suspect this
as the beginning of the bearings being damaged and the seal too? (Event zero?)
A low water level could be the starting point. Anything that causes the pump to run dry will do it. The damage to the bearings is usually comes after the seal gives out and starts leaking.
What's interesting is that the motor serial number says O80L which dates
to Dec 2005 as a mfg date. If so then the motor seals are supposed to be
resistant to damage. We don't have records that show the motor water
replaced though which is the enigma.
It is the pump seal that is leaking which is not a part of the motor. Anytime the pump runs dry for a length of time the pump seal is likely to leak. It is a cheap part to replace with most of the cost involved being labor.
I've been only running the pump long enough to cycle the water.
4 hours at most per day so as not to have longer term problems.
I've had to manually add water to the strainer basket each time
I power on too. It won't prime after being off unless I do.
This is why it was dry when set to turn on automatically.

There is a discinct sound of escaping air (a hissing sound) around
the motor even when the pump has been off for a while. Is this
related to the seal being bad? Air in the system bleeding off through
the bad seal?

It sounds to me like there is probably more than one leak at the pump. They sell a kit that includes all the orings and the pump seal and that is probably what the pool man will install. The faster the pump seal and any leaks you have at the pump are fixed the less chance of further damage to the motor.

Postby **Henry_R** » Wed 08 Jul, 2009 23:56

So if it overheats at least it doesn't open like a fuse and become unusable.
That's good to know since I would have thought the opposite since there's no reset switch.

We have a bid to replace the o-ring and seals at the pump and valve. We've accepted it even though
it's the only one 'cause it seems reasonable.

Does $143 sound good for replacement of the seals? $85 of that is labor.
The rest is parts and sales tax.

Probably not something that can be determined since I'll bet your area is different that Houston.

With some luck he can do the work before the weekend. I don't won't hold my breath since he had said he had 20 other calls that day and it was 11:30 am when he was here. Obviously he's swamped.

Postby **Denali** » Thu 09 Jul, 2009 05:40

Glad you found someone to get it done. As for the price, I don't know if that is a reasonable price or not. It's not a job that takes very long if you know what you're doing. It doesn't look unreasonable to me though.

If all the leaks are sealed you shouldn't lose prime which is a good thing.

Postby **Henry_R** » Thu 09 Jul, 2009 15:19

We're waiting to hear a price on the bearings before having the seals fixed; the logic is one trip, one job, one price. Hopefully it won't be too long or too much money.
A new pump/motor is only $400 and the motor is half of that cost.
The manager seems to think $100 for the bearings, but I'm skeptical.
Question is are they readily available or some kind of special order that'll take two weeks?
It's a centurion A.O. Smith motor so that should count for something of the parts being
available, I hope.

In the mean time the pump won't prime at all now. I manged to backwash the filter,
but it wouldn't prime enough to filter. The PSI gauge barely register 2psi.
I put water into the strainer and it wouldn't fill to the top. By the time I started the
motor the water was gone. I guess this means we can't circulate any water at all
until it's fixed. So much for keeping up with the algae. It's gonna start growing by
tomorrow night since the chlorine dropped two points since last night 6ppm
down to 4ppm. It's 105 outside(heat index) so I'll expect that chlorine will be
almost nil by tomorrow.

Is there anything we can do in the mean time to keep the algae at bay besides
just shocking the snot out of it every two-three days?

Postby **Denali** » Thu 09 Jul, 2009 19:15

Henry_R wrote:We're waiting to hear a price on the bearings before having the seals fixed; the logic is one trip, one job, one price. Hopefully it won't be too long or too much money.
A new pump/motor is only $400 and the motor is half of that cost.
The manager seems to think $100 for the bearings, but I'm skeptical.
Question is are they readily available or some kind of special order that'll take two weeks?
It's a centurion A.O. Smith motor so that should count for something of the parts being
available, I hope.
The parts will be available, no problem with that.
In the mean time the pump won't prime at all now. I manged to backwash the filter,
but it wouldn't prime enough to filter. The PSI gauge barely register 2psi.
I put water into the strainer and it wouldn't fill to the top. By the time I started the
motor the water was gone. I guess this means we can't circulate any water at all
until it's fixed. So much for keeping up with the algae. It's gonna start growing by
tomorrow night since the chlorine dropped two points since last night 6ppm
down to 4ppm. It's 105 outside(heat index) so I'll expect that chlorine will be
almost nil by tomorrow.
That is tough with that hot weather. Probably the best to do is shock it and brush it to mix up the chemicals. Certainly worth keeping the ppm up after all the work you've done.
Is there anything we can do in the mean time to keep the algae at bay besides
just shocking the snot out of it every two-three days?