Head pump jammed

[galway2004]

We have a typical Jabsco head on our Catalina 38. The pump jams a bit and “pops” back up, water from bowl doesn’t flow through to holding tank. In other words doesn’t flush. Have tried head lube, and have confirmed no clogs in hoses from the head to the holding tank. Even replaced the pump for the head, thinking valve was defective. But same thing. Any ideas out there? Thanks all

[fregata]

Is your holding tank vent clear? I’m no expert but the symptoms sound like pressure is building in your holding tank.

The same thing happens to me if I have the head set to overboard discharge and try to pump it with the seacock closed.

[HopCar]

The obvious thought is that the discharge is blocked. As Fergana said a blocked vent might cause those symptoms.

Another problem that people don’t often think of is that for the piston to go down, either water or air must come in on top of the piston. If air or water can’t come in on top of the piston, it creates a vacuum that causes the piston to rebound as you describe. Take a look at the wet/dry flush valve at the top of the cylinder.

[peghall]

There's another possibility: a problem that's very common in Jabsco manual toilets--a failed wet/dry cam. The wet/dry "valve" is actually just a little "gate" (the cam) that the lever swings to block or unblock the flow of incoming flush water. Due to either a tooling or mfr'g flaw, it hangs up...creating back pressure that feels like pumping against a clog or blocked tank vent, except it only happens in one mode--usually the wet mode.

The cure: replace the wet/dry cam assembly. Jabsco often sends out a new one for no charge...but then you have to take the pump apart to replace it, which can be a PITA and really messy because you can't flush water through the pump to clean it out before you take it apart.

So my advice: just replace the pump instead. It's prob'ly overdue for a rebuild or at least a joker valve --and besides,service kit costs almost as much as a pump, which doesn't cost that much anyway... and swapping it out only requires removing and replacing the 4 bolts that hold the pump on the base and two hoses, which beats the socks off taking the pump apart!


--Peggie

[Sarks757]

Brand new toilet on my Beneteau. I replaced it about a month ago -NOW, hand pump will not eject any fluid from the bowl with much resistance on the up and down. Moved L- R the handle on the wet dry- on the dry cam side pump m has great resistance. .. when on the wet side of the cam valve, It will add water to the bowl, but no water ejecting to the outside of vessel, and yes all Thru Hulls are open..

[peghall]

Sounds like a blocked tank vent has pressurized the tank, creating back pressure that's preventing the flush from going anywhere.

The two most common locations for a vent blockage are the vent thru-hull and the other end of the vent line--that end of the hose and the vent fitting on the tank. Start by cleaning out the thru-hull...use a screwdriver blade, ice pick--whatever works. If that doesn't result in a spew out the vent, you'll need to relieve the pressure before removing the vent line from the tank to clean them out...so open the deck pumpout fitting VERY CAREFULLY with a hose at the ready. Be sure you're UPwind of it! Scrape out that end of the vent line and the vent fitting on the tank...reconnect the vent line.

Do not use the toilet again or attempt to pump out until you're sure the vent is open.

If this also happens when flushing directly overboard, your new toilet may have a defective wet/dry cam assembly. Paul Campagna is Jabsco's toilet guru...call him tomorrow his direct line is 978.282.5246

--Peggie