Pump Not Priming: Narrowing Down the Issue

[razzle]

Hey guys,

I've been having issues with my pump attaining full prime since I moved into my house 9 years ago. I've had 2 pumps, both with similar issues. On the suction side I've ruled out an air leak for these reasons. Feel free to correct me on this.

1. The 1st diverter valve (pool vs hot tub) achieves the same level of prime no matter the position.
2. I've run water over all areas of the plumbing, including special attention between the 1st diverter and the pump.
3. I've also wrapped plastic bags around all connection points with no success.

So my attention has shifted to the filter which has the following issues:

1. There are 2 cracks in the elbow/bulkhead assembly (see pic). This cracks do not extend to the other side, however.
2. There is no o-ring on the connector where the larger cartridge filter is placed.

I should also mention there is never any water leaking from any part of the pool equipment.

I've included pictures of the inside of my filter in case you guys notice anything else. Filter is a Sta-Rite S7M120.

I'm going to go pick up a new o-ring today to see if this helps.

Any other thoughts would be appreciated.

Thank you!

 

[Texas Splash]

The cracks in the PVC might be letting air into the system when it's OFF, which would then let water out of the pump pot resulting in a slow prime cycle at start-up. But if the pump is simply not achieving full prime even when running, its more than likely still a suction side leak. Since it has been happening over many years with two pumps, I would be inclined to think it's something either in that actuator valve (even though it seems to be fine) or the plumbing. Other things that might interfere with pump prime would be the skimmer weir door getting stuck, low pool water level, or a possible blockage in the suction line.

One final item that can give the appearance of a suction leak effecting the pump pot's water level is the filter itself being very dirty. If water can't flow through properly, it causes a backlog and churning in in the pot and that water level can eventually fall lower & lower.

 

[razzle]

Thanks for your help! I patched the cracks with some epoxy putty and replaced the O ring. The pump has been fully primed for the last week.