Getting air in System when vacumming

[xlot]

I have been beating my head for weeks on this one. I would appreciate a second brain on this.

I have no air in my system when My pump is running on either the main, vacuum or skimmer line (6 yo pentair single speed 1hp). Air starts when I plug my vacuum into the vacuum line. It also gets air from the skimmer line when I hook it up to there. Pressure in all 3 lines is 7psi when only on the respective line. When I plug in the vacuum in drops to about 5psi on both vacuum and skimmer line. On the Vacuum line water will begin to surge and I cannot run the vacuum. On the skimmer line it will vacuum but, lots of bubbles. My trouble shooting went as follows.

Thought initially a blockage in the vacuum line so I
- blew the line with a bladder
- ran a rope and rag through the line
- reworked the plumbing and have it able to pump backwards through the vacuum line.
-have not found a blockage in the vacuum line, I have also back flowed the skimmer line and nothing.

Started to think air leak on the suction side
- remove vacuum hose and used only the angled hose to wall adapter from the zodiac mx6 and problem occurs, so its not the vacuum or the vacuum hoses just seems to happen when restriction occurs or more load on the system.
- removed / replaced / lubed all seals
- checked for cracks in the pump lid.
- replaced and re-seated pump fitting seals.
- checked pump plugs
- checked all fittings above ground with shaving cream
- poured water over everything
- taped a plastic bag around all fittings up to the pump including the jandy valve and filled it with water. still no change.

- opened the pump and impeller was clean
- not seeing anything with a dye test
- trying a bucket test for the next 48hrs now.

I'm finding it hard to believe it is an above ground air leak. To have a similar issue occur in both the vacuum and skimmer line I'm thinking an underground leak is probably not it either.

When I simulate a restriction on only the main valve with the jandy, it does not seem to phase the pump!
Would you guys think the pump itself (being that its old) could cause this kind of issue?
The symptoms happened literally over night.

Thanks for any help / suggestions!!

 

[Jimrahbe]

x,

Pumps often can't suck enough water through a vacuum hose. If your valves allow it, you should adjust them so that most of the suction goes to the vac line while a little suction goes to the skimmer or main drain. The two sources allow the pump to get enough water.

Thanks,

Jim R.

 

[xlot]

x,

Pumps often can't suck enough water through a vacuum hose. If your valves allow it, you should adjust them so that most of the suction goes to the vac line while a little suction goes to the skimmer or main drain. The two sources allow the pump to get enough water.

Thanks,

Jim R.

Thanks for the reply!! I did that, but It still has the issue. I also tried partially opening the main drain. Any way I try it I get the same results (air) up until there is not enough power through the line to operate the vacuum.

 

[oldprophet]

The hoses on the mx6 are notorious for leaking air due to early failure, especially around the connection cuffs and the 45 wall connector.

 

[xlot]

Your absolutely right, I have gone through 20 or 30 of those hoses over the years.. I tend to just replace the entire unit every three years. 10 hoses tend to cost almost as much as the whole package.

Just an update, I purchased a cheap ($50) endoscope off amazon. Let my pump suck 50ft of string up into the basket. Opened the basket and attached the endoscope to the string and pulled the 50ft endoscope about 30ft in (that's as far as I could get it). cut the string and turned my pump back on, pulled the endoscope back poolside while recording until I did not see bubbles anymore.. moved the camera around and found the leak!! uggg... now comes the jack hammer..

Thanks for everyone who helped!!

 

[Jimrahbe]

x,

You think the leak is in the underground PVC plumbing???

Thanks,

Jim R.