GM head not draining

[PeterK]

I thought it prudent to ask advice before I start tearing things apart...

Had a GM pump rebuilt last December and while re-installing replaced the hose from the pump to the tank including a new vented loop. Of late, every third or fourth use, the bowl won't drain. A quick plunge gets it going but I want to fix the problem rather than treat the symtoms.

Suggestions, please? Is it possible the hose from the bowl to the pump needs R&R?

As an aside, I just tarted using Noflex and the pump out boat operator said he could tell the difference after only 2 applications. I'm working with someone on a knock off which should be sold for less than $20/bottle including shipping. I'll post info if it comes to fruition.

 

[SEVEN]

Sounds like the stator is going bad. I had the same problem and once I switched them out the problem was solved. Good luck

 

[PeterK]

Sounds like the stator is going bad. I had the same problem and once I switched them out the problem was solved. Good luck

In and out stators plus rotor & blade replaced in December of last year.

 

[JLR]

Make sure that no part of the hose that goes from the bowl to the pump has any belly in it that is below the level of the pump.

 

[davidwigler]

Have you removed the copper line on top of the pump? Use 1/4" pipe plugs.

 

[Toolsntoys]

What is the purpose of the copper line?

 

[davidwigler]

I believe it was to prime the pump but is now recommended to be removed.

 

[davidwigler]

Could you be holding the flush button until the bowl empties introducing air?

Maybe your strainer is blocked slowing the incoming seawater.

 

[PeterK]

Dave, mine does not have the copper line. I will doublle check the strainer but the bow seems to fill fine. It will overfill every time if I hold the flush button a full five seconds. There are 2 other heads aboard that are working fine so I am assuming it is not a tank vent blockage.

JLR: large hose from bowl to pump is fine. It is only about 2-3' long with a 6" vertical drop. I suppose this is the first thing I should check to see if it has build up in it?

Is it possibe there is an issue with the new vented loop, i.e. a clog? BTW nothing other than single ply TP and waste ever go into this head. Further, it is primarily urine in this one: the yellow bowl.

 

[JLR]

Dave, mine does not have the copper line. I will doublle check the strainer but the bow seems to fill fine. It will overfill every time if I hold the flush button a full five seconds. There are 2 other heads aboard that are working fine so I am assuming it is not a tank vent blockage.

JLR: large hose from bowl to pump is fine. It is only about 2-3' long with a 6" vertical drop. I suppose this is the first thing I should check to see if it has build up in it?

Is it possibe there is an issue with the new vented loop, i.e. a clog? BTW nothing other than single ply TP and waste ever go into this head. Further, it is primarily urine in this one: the yellow bowl.

Problem with vented loop would likely make bowl fill on its own.

 

[Fair Well]

Has anyone (you or PO) ever changed out the hoses? I did mine two years ago and all were blocked with calcium deposits. some were blocked to 75% or more. Hear is a pic of a pump with a partially blocked discharge line. The others are things that I found in the pumps that I rebuilt. Some things just don't flush. Even got paid to rebuild one (one Peso) LOL! Had some pic of the 2" hose that were closed down to about 3/4" but they were on my other phone that took a deep dive off shore.