Suction issues

dombey

Well-known member
Apr 25, 2010
76
Oregon
Hi all,
Just went through a battle with my pump. Couldn't get it to prime after it ran dry while I was traveling for a few days... Replaced all the seals and rubber parts and inspected the rest, now it is working.
HOWEVER...
I am having issues with my pool cleaner 4x. It is moving VERY slowly around the pool, but otherwise seems to be functioning.
I am seeing about 15 PSI on the filter. That isn't much different than I normally see.
I have played with the jandy valve that adjusts between the main drain/skimmer and the vacuum cleaner.
What I have observed, which never happens normally, is that when I adjust the jandy to put more suction on the pool vac, I see a dramatic drop in filter pressure...<5 psi. With the reduced pressure, the pool vac runs even slower (basically stops) despite allocating more pressure towards it.
Additionally, I seem to have a pretty consistent flow of air bubbles coming out of the return jets. That has been a pretty consistent thing since I bought the house 3 yrs ago... But worth noting that the seal replacements didn't fix that... I have no above ground air leaks that I have been able to find.
I am thinking it has to be some kind of leak or obstruction in the pool vac line...?
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,879
Silver Spring, MD
A very small air leak would cause exactly the symptoms you describe.

I suspect your pump strainer cover is not sealing properly, allowing air to get into the system. No doubt you managed to mostly seal it, or it wouldn't have primed, but one way or another something is letting air in on suction side of the pump.

When pumps run dry, they tend to overheat the pump housing, which can warp, making it difficult (or impossible) to seal the strainer lid.
 

dombey

Well-known member
Apr 25, 2010
76
Oregon
Ok, update:
I'm making progress but not quite there yet:

The new single segment 35ft hose arrived today and I installed it. Works great and both connections are under water. I let it run for an hour here is what I am observing:

-filter pressure at 15 PSI with the jandy in normal position. Normal position is with the handle at 2:00 which places more emphasis on the pool vac than the main (equal at 12:00).

-if I move the jandy to 12:00, and thus equalize the pool vac and the main, I get an increase in filter pressure to around 17-18 psi.

-if I turn the handle to 9:00 (pool vac OFF), I get 15 psi.

-if I turn the jandy to 3:00 (main OFF, pool vac at 100%), I get 1-2 psi.

- if I go TOO heavy on the pool vac, I not only get lower pressures but also substantially more air bubbles coming out the jets.

-I would like a bit more oomph out of my pool vac, but the more emphasis I put on it, the more the pressure drops and thus I don't get more oomph.

So, if I am thinking about this correctly, I believe I can draw the following conclusions:

-the problem is not occurring downstream from the jandy valve; meaning my pump, basket, etc lines are all good. This conclusion follows my finding that closing the vacuum lines on the jandy seems to work just fine w no bubbles, healthy pressure, etc.

-there is nothing wrong from the main drain and skimmer returning to the pump, per the same finding above

-there is nothing wrong with the pool vac or flexible hose

-which leaves me with two potential items:

1. Jandy valve is bad
2. Lines running from pool to pump on the vacuum circuit are leaking, obstructed, or somehow otherwise FUBAR

Are these correct conclusions based on the evidence?
 

Melt In The Sun

TFP Expert
LifeTime Supporter
Oct 29, 2009
3,899
Tucson, AZ
I think your problem is at the pump.......because 99% of the time it is. Humor us and check the o-ring for the lid (new non-petroleum lube too), check the drain plugs (t-tape), and if that doesn't help then next would be the threaded connection at the pump inlet. It certainly could be elsewhere, but almost always the problem is right there at the pump.
 

dombey

Well-known member
Apr 25, 2010
76
Oregon
Melt In The Sun said:
I think your problem is at the pump.......because 99% of the time it is. Humor us and check the o-ring for the lid (new non-petroleum lube too), check the drain plugs (t-tape), and if that doesn't help then next would be the threaded connection at the pump inlet. It certainly could be elsewhere, but almost always the problem is right there at the pump.

You've been humored. :)
Just checked the o-ring on the basket for the 49th time...it is a brand new ring and lid...well lubed, and I can see through the lexan a solid back line where the ring meets the lexan...it is about 1/8" wide, in a continuous ring around the lid...it is definitely sealing tight.
Checked the drain plug, it is completely dry, tight, I guess I can remove it tomorrow and put Teflon tape on it, but given It is under water you'd think it would be dripping if it wasn't sealing?

I actually don't have a threaded inlet...the pump side is threaded but it has been glued into place (was that way when I bought the house). Again, bone dry, have sprayed with soapy water trying to hear or see anything to no avail.

I do have a couple of drips but they are all on the pressure side of the pump and very, very slow...
 

mpnret

Well-known member
May 27, 2013
114
NJ
I realize that this most likely has been done, but I don't see it mentioned anywhere that the pool vac line was tested without the pool vac attached. Could also try plugging your new vac hose and vac into the skimmer to isolate some things.
 

dombey

Well-known member
Apr 25, 2010
76
Oregon
Will do this evening. I did both of these things with the old hose, which is how I discovered the leaky hose...but now that I've eliminated that problem, I will retest.

I also ordered a Drain King just to have around...should I need to go there.
 

Enjoying this content?

Support TFP with a donation.

Give Support

dombey

Well-known member
Apr 25, 2010
76
Oregon
Ok, so I found roughly equal performance from the pool vac when switching from the dedicated suction line to the skimmer.
I also noted that when disconnecting the pool vac, turning the jandy to 100% pool vac (0% main/skimmer) still causes a big pressure drop... But instead of the 1-2 psi when the vac is attached, it is now 8-10 psi. This is about the same as what happens when I turn the jandy the other way and I assume it is caused by cavitation? The noise is definitely there.

So, next steps I think are to open up the pool vac... Probably time for a rebuild...
 

mpnret

Well-known member
May 27, 2013
114
NJ
I am assuming that when you are running with both suction lines open your air bubbles are gone and cavitation isn't an issue. The pressure drop when you switch to the individual lines sounds a little high but most likely it was always like that. At least the drop is the same for both lines so any kind of obstruction is highly unlikely. I would concentrate on fixing the pool vac.
 

dombey

Well-known member
Apr 25, 2010
76
Oregon
mpnret said:
I am assuming that when you are running with both suction lines open your air bubbles are gone and cavitation isn't an issue. The pressure drop when you switch to the individual lines sounds a little high but most likely it was always like that. At least the drop is the same for both lines so any kind of obstruction is highly unlikely. I would concentrate on fixing the pool vac.

Right. The air bubbles go crazy when I turn the jandy too far and the filter pressure drops. Huge bulges. But if I adjust it to a point where the filter pressure is not dropping significantly, they die down and it is more of a light sparkling.
 

dombey

Well-known member
Apr 25, 2010
76
Oregon
Took the cleaner apart today...seems fairly obvious what is wrong. The two driveshafts on either side of the large wheels ("main drive shaft" and "steering sliding assembly" in technical terms) are completely worn down to where there is essentially no contact with the wheels. So I think I'm getting a ton of slippage and not a lot of driving...which would explain the slowness of the cleaner.
Of course the parts are outrageous. $75 shipped...could have saved a few bucks if I wanted to order from an unknown source but went amazon prime...will be in business by Monday at the latest.
 
Thread Status
Hello , This is an inactive thread. Any new postings here are unlikely to be seen or responded to by other members. You will get much more visibility by Starting A New Thread