Suction side air leak, any ideas?

[mikegmi2]

Had an air lead last summer...never figured it out, closed the pool. This was my first (half) season with this pool.

Beginning of this season, opened the pool myself, and the air leak was still there. I decided to do some research, and one day I did 3 things:

1. Swapped the pool pump lid with the spa pump lid (figured the people that opened the pool for the previous owners may have mixed them up since the previous owners did nothing...they didn't even know what the timers were on their own pool).
2. Got new o ring and lubed, for pool pump lid.
3. Took apart and added Magic Lube to the union o ring just before my pump.

To my surprise, the air leak was completely gone! Not even a tiny bubble in the pump lid. Well, this lasted about 10 days, and then the air leak slowly returned. Cavitation and air bubbles in the pump lid, and my sand filter slowly fills with air. I have done all the same things over again, because I figured it had to be one of these things that fixed it...but repeating these steps has not fixed the leak. I even went and got a new o ring for the union just before the pump, and this did not help.

I tried the smoke test, and hose test on all these things and never noticed the air bubbles going away.

If I had to guess, I feel it is the pump lid. Could it be that the lube was temporarily making an air tight seal...and over the past 10 days it got sucked in and is now allowing air to seep in again? Can pump lids be this finicky? When I look at where the lid meets with the pump basket, it does look like there is a tiny gap there...but is this normal? Does the thick o ring around the perimeter basically get squished down between the lid and basket? Maybe I just need to tighten more? I'm scared to break something...or do these type of lids just need a lot of lube to make the air tight seal? Or maybe I have the wrong o ring altogether? It seems to fit well, so I don't know.

I've attached some photos to aid. It is super annoying to see the bubbles pump into the pool, and having to use the bleeder valve on top of my sand filter to let the air out every day!

 

[PoolGate]

You said you tried re-lubing that oring again but it didn't help? Is it a new oring? If it was the oring, slowly pouring water over it would seal it up. I have also seen the plastic in the lids crack at the seems it is hard to see but look closely.

 

[mikegmi2]

The o ring for the pump lid was new as of late last summer. I didn't re lube it, but took the lid off once or twice and re-tightened it. When I look closely I do see a bit of 'movement' in tiny areas around the perimeter of the inside of the o ring...wasn't sure if this was just little areas where the air bubbles from the inside are moving around...or if this might be a tiny air leak? I am going to lube the Crud out of the lid when I get home and see what happens...focus on 1 thing at a time until I get some results or lose my mind.

One question I did have...when you have an air leak, is it normal for the air to collect in the filter? The see through plastic on top of the filter...I can see the water come all the way up to the top almost when I let out all the air...and then after a few minutes, I will watch a big air bubble come up and take the water level down to where I cant see the water anymore. I can let the air out, and then a minute or 2 later the big air bubble comes back and takes the water level back down...this is normal and where the air will go correct? I think there is a small plastic hose in the filter that goes up to the top with a screen on the end, that is designed to collect the air and move it up to the top of the filter space?

 

[PoolGate]

Yep totally normal if you have an air leak air will accumulate in the filter.