Jabsco Joker Valves.

Norman_E

Norman_E

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What a hopeless piece of **** they are. They may be OK if your heads discharges to a holding tank in the bilge, but if you have holding tanks above the level of the heads they are pretty useless. I have replaced mine many times but despite an absolute ban on putting paper in the heads they all fail to prevent the liquid in the pipe up to the tank from leaking back to the bowl after a short period of use. Some fail immediately on installation. The locking pump handle that is supposed to hold the flap valve shut is equally useless at preventing flowback. Has anyone had success with fitting a non return valve into the discharge hose immediately after the joker valve fitting? If so what type. I have seen spring loaded ones but wonder if the pump is up to the job of forcing waste past them.
 
Most cheap nrvs allow a bit of backflow unfortunately. You could put a ball valve in the line which you could shut when not using the head.
Bit of a pain but positive action.
 
The only leakage back into the bowl should be clean seawater. (and not much of that)

If you get anything other than seawater back, then there was insufficient flushing.
Imagine the contents of your home toilet cistern, and pump that much seawater through.
 
The Jabsco instructions advise to pump at least 8 strokes for each metre of outlet hose, in our case with 2metres, that means at least 16 strokes of the pump. That seems tedious, but far less so than have to strip out hoses that are blocked with hard concretions. I have taken the pump apart a number of times, and there has never been any sort of deposit on the joker valve or anywhere else other than some superficial slime.
 
MM5AHO said:
The only leakage back into the bowl should be clean seawater. (and not much of that)

If you get anything other than seawater back, then there was insufficient flushing.
Imagine the contents of your home toilet cistern, and pump that much seawater through.
Click to expand...

We have the same difficulty as the OP, our holding tank is above the level of the heads and although we pump lots of clean seawater through the system the pressure of the head of water in the pipes going up to the tank and around the swan neck results in slow, but steady, return of the clean seawater into the toilet bowl. The joker valve does not seem robust enough to resist the pressure, I too have tried replacing the valve with new ones but they seem to have little impact.
 
If you've got a holding tank, you don't want to pump too much flushing water through or it will fill up in no time. Conversely you don't want to pump too little either - difficult balance. I don't have the problem as I have a portapotti (which has it's own drawbacks).
 
If your holding tank is anything like mine, the answer would be to pump the waste into the tank, then close the tank and flush through as recommended. The small amount of waste in the intermediate section shouldn't be enough to cause concern.
 
Surely there is some confusion here as it's the lower "flap" valve which is supposed to stop the the back flow - this is the valve which the "twist and lock" handle locks into position. The joker valve is in the outlet pipe and it looks as if it would struggle to stop back flow unless it was in perfect condition because there are a lot of potential "gaps" in it.

Richard
 
I just put yet another new joker valve in. So far its holding. I have converted the heads to grey water flush which saves tank capacity, and am hoping that without seawater to react with urine and produce a hard deposit the valves will stay watertight for longer. the grey water is pumped in electrically, and the Jabsco pump is now for pump out only.
 
RichardS said:
Surely there is some confusion here as it's the lower "flap" valve which is supposed to stop the the back flow - this is the valve which the "twist and lock" handle locks into position. The joker valve is in the outlet pipe and it looks as if it would struggle to stop back flow unless it was in perfect condition because there are a lot of potential "gaps" in it.

Richard
Click to expand...

That is true, but in practice the flap valve fails miserably, and if the twist and lock feature is used I find that the pressure on the flap valve distorts it and makes it leak still faster. IMHO the whole design is badly flawed. A good system would feature separate in and out pumps probably made of bronze with decently engineered valves, but I can't afford a Baby Blake!
 
I've had many boats, both motor and sail. The ONLY sea toilet to never give problems was the old Baby Blake. Every other one we've had, either flushing directly overboard, or to a holding tank, has caused endless problems. As previously stated, I think there's a basic and intrinsic design issue.
Jabsco/ITT pumps are a joke! Fine if you only spend a few weeks a year on board, but anything more and they’re usless imo. Seriously considering the only one we haven't tried; the Lavac.
 
I've had a jabsco heads with overhead holding tank for the last 3/4 years and only once had a problem with contents returning. On a trip to Holland the holding tank had been closed for about 3 days and I found the bowl filling up with the contents of the holding tank. The vent pipe to the holding tank had become blocked and on a nice sunny day the "fermenting contents" literally inverted the joker valve with the increasing pressure.

Would suggest checking the holding tank is not pressurising when you pump the bowl contents into it. I also use brick cleaner (dilute hydrochloric acid) a couple of times a season to stop calcification of the system.
 
A potential business opportunity to offer a direct replacement that works for circa £100?
It would be a pretty sizable market ....Not sure it could be done for £100 though
 
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