head isn't pumping water

[Aquah0lic]

I tried out the head today and it isn't sucking water in. The seacock (both) are open. Do I just need a rebuild kit or is it something else? Thanks.

Two quick checks. First, make sure the thru hull is not blocked. Second, make sure the anti siphon is not stuck open. Depending on the head you have, there is a way to prime it. Take loose the hose that runs from the pump to the bowl. Take it loose at the bowl. Fill it with water, then reconnect it, and start pumping. If this does not work, and everything eslse is in order, you likely need a rebuild.

[Stillraining]

FWIW..I spent the 69.00 for the rebuild kit and it did absolutely nothing to improve mine...I fear my pumps cylinder walls are beyond useful life..not worth the price differance between that and a new one now...so its out with the old and in with the new this spring.

You might tray a little lithium water pump grease on both the shaft packing and the pump swap packing for a temporary fix at getting prime.

Good Luck

Edit: KAI NUI ...thanks for the tip on the anti siphon...I will check that as well...didnt think of that.

[highseas]

I had same problem with my Jabsco head,replaced flat gasket that has little brass flapper valves.Worked fine ever since,too bad my relationship didnt.

[Charlie]

I recently rebuilt the head and then replaced all of the sanitation hoses. It is amazing what a difference this makes. Now I need to replace the holding tank. The pumps are prettyy easy to figure out (On the jabsco head anyway) I spent an hour rebuilding and then rerebuilding the pump till I figured out that I had opened the wrong seacock for the head water. Before the rebuild the pump was very hard to pump and didn't let much water in. Sometimes none. Have tried putting some vegie oil in the pump to lubricate it.

[RBEmerson]

A quick test: disconnect the inlet line to the head's pump, put it on flush (not "empty bowl"), put a finger or thumb over the pump's intake barb, and pump. If the pump's in reasonable condition, you should feel suction forming on your finger. If the pump's really good, it'll stiffen up and you'll feel a lot of suction. If there's no suction or very little, make sure any assembly screws are reasonably tight (do not overtighten them or things will probably warp, break, or strip out). Check the piston o-ring (usually, the piston is just a disk with an o-ring around the edge). If it's worn... no pumping action.

As to the anti-siphon valve, under no circumstances should there be a an anti-siphon valve between the water inlet and through-hull. It must be between the pump and bowl. If it's on the intake side, the pump will suck air and not work. Putting tape over the vent in the valve will stop the air leak. And kill the anti-siphon function. Not Good.

[highseas]

Trust me ,just change the rubber flat gasket.

[RBEmerson]

Depends on the make of commode. BTW, Aquah0lic, it might help to know the make and model.

[Stillraining]

Originally Posted by highseas

Trust me ,just change the rubber flat gasket.

I trusted you...it still dosent work......I have a Raritan PHII though.

[RBEmerson]

In case you don't have an owner's manual, CLICK HERE. Past that, check the four bolts that hold the pump cylinder to the base (the flapper valve at the base will control black water coming into the pump from the bowl but shouldn't influence drawing raw water into the pump). There are three other seals to check, the collar seals around the piston shaft and "dry/flush" valve shaft, and the o-ring on the piston. The dry/flush valve seal shouldn't matter too much, but the piston seal and piston o-ring matter a lot. If you can't get suction when pumping, one of these three points is most likely at fault. Or, as you said, it may be the cylinder wall is shot.

Vic Williams and the rest of the Raritan Engineering support crew are skilled and helpful. If all else fails, give 'em a call.

[Stillraining]

All thoes seals came new with the kit..didnt help...new head will replace it this spring if its not the vent as stated above...Thanks for the link

[MidLandOne]

Originally Posted by RBEmerson

As to the anti-siphon valve, under no circumstances should there be a an anti-siphon valve between the water inlet and through-hull.

Claiming "under no circumstances" is poor advice because it is perfectly possible to put the antisiphon between the pump and the seacock without destroying the pump suction provided one knows the proven and safe method of doing so. Doing so results in a much tidier installation.

But assuming it is not a new installation it is likely not the original poster's problem so I won't bother arguing with you about that here . I think many here are coming to know that I know what I am talking about on such matters even if you don't .

[RBEmerson]

How scored is the pump cylinder wall? For that matter, how old is the head? Generally, what's killed the heads I've dealt with is either the seals or warping in the plastic mating surfaces. You replaced the seals, so that leaves either the wall or a warped base. How badly does the overall head leak? I don't recall you're saying something like "water dribbles out of..." or "water squirts out of...", but maybe you're coping with water leaks, too? In general, though, it's air leaks on the inlet side that keep most pumps from working if things are otherwise OK.

[donradcliffe]

Don't forget to test the water inlet by removing the inlet hose from the tolet, holding it below the waterline, and opening the thru-hull to see if water pours out. If the boat hasn't been used in a while the sea-critters can block the thru-hull.

[RBEmerson]

A good point. Keep in mind, though, that if the pump's sound and the inlet is blocked (closed seacock or too much crud in the through-hull or hose), the pump will stiffen up fairly quickly as a vacuum forms between the pump and the outside of the boat. If I understand the symptoms correctly, this isn't happening with this boat. Or is it, Aquah0lic?