No Prime. No apparent suction side leaks. Pump leaks internally somewhere but works.

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J

jimingreen

0
Jul 20, 2013
27
Akron, OH
This site has been a Godsend. Last summer I bought a home that came with a pool which was installed in 1980 and I have overcome numerous age related problems thanks to TFP. Although I have been reading and using this site for almost a year, this is my first post.

My current seemingly unsolvable dilemma is that my pump will not prime and I cannot find an air leak if that is the problem.

For some background, I am off to a late start opening the pool. I got everything put back together and started the pump but it would not prime. It has always been slow to prime and last year it always had some air in the pump basket. I worked at it for several hours doing all the plumbing diagnostics recommended on here. I could not find any suction leaks. I was about to give up for the night and then for no apparent reason it slowly started to trickle in and primed and started pumping away. It worked for about four hours and then I had to clean the basket so I opened it up and I was not able to get the prime back after cleaning it out.

At this point I was convinced it was a lid leak. I greased the seal. No prime. Then totally removed the seal and thoroughly cleaned it and smeared grease all over everything that looked like it would benefit from grease. Still no prime. Next I took the seal out and degreased it and everything else and glued it back in with RTV form-a-gasket and then glued the lid down on the gasket. Form-a-gasket was gushing out all sides. When that did not fix the problem, I unmounted the pump and turned it over to submerse the lid seal. It did not leak.

Next I turned my attention to the plumbing. The system was plumbed with poly pipe, barbed fittings, and clamps and the pressure side has sprung leaks on several occasions. Even though I could not find a suction leak, I was now totally convinced it was a loose fitting somewhere so I replaced all of the above ground plumbing to and from the pump with PVC. Still no prime.

I decided to water test the suction side. I plugged the line in the skimmer and filled the pump basket to the rim and let it set overnight. It leaked water out to below the suction inlet and there was water coming out at the junction of the pump body and the motor.

Now I was convinced it could not prime because the pump was sucking air in through the pump internals somewhere. So to test the pump, I unmounted it and installed a short section of suction pipe and put it directly in the skimmer. When I turned on the pump, it was shooting water like a fire hydrant and I mean it was spraying a stream of water all the way to the neighbor’s yard.

Next the only thing left that I could think of was the underground. I plugged the suction side again in the skimmer and filled it with water to the top of the pipe. The water level never dropped at all. Not convinced with that, I decided to pressure test it with air. I blew out the line with a shop vac and plugged it underwater in the skimmer while it sprayed water in my face. I rigged up a pressure test setup and pumped 30 pounds in it. It held for about 5 minutes and then my plug in the skimmer shot out like it was shot from a gun and was never to be found. I got another plug at Home Depot and weighed it down in the skimmer with bricks to avoid another incident. This time I put in 15 pounds of air and it never dropped pressure one bit over about 4 hours.

So now I am left with no prime since Friday. No apparent suction side leaks in the plumbing all the way from the skimmer to the pump inlet. The lid has been completely glued down with RTV. The pump does have an internal leak somewhere but it does work at watering the neighbor’s yard when it has a 2’ long suction pipe. Still no prime when it is hooked up like it is supposed to be.

What should I try next?
 
Did you use teflon tape or pipe dope on any threaded fittings you have on the suction side of the pump?

I had TONS of air in my return line this summer after putting new unions on the pump. I used a good amount of teflon tape on each prior to installtion - and that was the problem. They simply didn't seal well enough. I removed them, applied a generous coat of pipe thread sealant and that solved the problem.

http://www.homedepot.com/p/Hercules-8-oz-Megaloc-Thread-Sealant-158062/100153125

It's another avenue to check out...
 
I filled the male threads with pipe dope, then two wraps of teflon tape over that, then more pipe dope over the teflon tape. Using this method I have never had a threaded connection leak. I used smoldering incense sticks to check for leaks but could not find any smoke being drawn in or disturbed anywhere. I also ran a garden hose at full stream on each joint and the lid seal but no change.

The pool pump is uphill and quite a distance from the pool skimmer. It is about a 3' uphill climb and about 45' of 1-1/2" poly pipe. I have a Hayward 1-1/2 HP Super Pump. I checked the pump sizing chart for the Super Pumps and the pump is sized correctly for my pool size and head conditions. Not over or undersized from what I can tell. My experiment of sticking the pump suction directly in the skimmer would be a substantial reduction in flow restriction compared to the actual installation conditions.

As a further experiment I filled the basket with water and put my palm over the suction inlet while turning on the pump. Although I could feel suction, it was not what I was expecting. I do not have another pump to compare it to so I have no idea if it is substandard.

Should I rig up a vacuum gauge? Anyone have an idea of what the vacuum should be?
 
As a further experiment I filled the basket with water and put my palm over the suction inlet while turning on the pump. Although I could feel suction, it was not what I was expecting.
Click to expand...
Did you put your fingers over the inlet in the pump basket strainer (basket removed) and then turn on the pump? That should have snatched your palm like a bulldog lunging backwards. Clarify that, please. Did the water in the pump basket get sucked in?
 
Have you removed and resealed the drain plugs on the pump?
Have you opened the wet end and checked for anything in the impeller?

Until the pump actually primes and is pumping water there won't be much vacuum at the suction fitting.
 
My palm was over the inlet on the outside of the pump - where the plumbing hooks up. Not the internal inlet within the basket. Sometimes I'm stupid enough to try something like that though. I'm getting desperate enough to try.

The front plug is epoxied in. I suppose it was striped out and would not seal earlier in its life. It makes draining a chore. I did not notice the drain plug on the middle of the pump when I winterized last fall so I have not removed it. I did check both for suction leaks multiple times through this ordeal. Come to think of it that water at the center of the pump was in there all winter long so hmmm that may have caused my current problem. That drain plug is there for a reason. The current leak is coming out of a small drain hole in the center of the underside of the pump. I figured the leak was the shaft seal at the motor to pump connection. It leaks so much that while the pump is not running it is leaking out continuously until the basket is drained.

I have looked down in the outlet and see nothing suspicious. I have not thoroughly tore it down to look at the impeller as of yet.

- - - Updated - - -

Oh and also when I palmed the inlet and turned it on, yes it sucked the water out of the basket even though my hand was totally blocking the inlet.
 
Well tearing down the pump turned out to be one of the simplest things I have worked on. There is very little going on in there. It turned out that the seal at the impeller was shredded and some of the pieces were even washed away. That was the source of the vacuum leak. I ordered a Go-Kit online to rebuild it. Searching Craigslist I found a 3/4 hp Super Pump so I bought it to get me through until the kit came in. The motor turned out to be bad so instead I took the best parts from both pumps and made myself a Frankenstein. Thanks for the help.
 

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