Replacing Jabsco Joker Valve

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houldsworth

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Got to replace this valve as loo keeps backfilling.
Presumably as you undo the outlet fitting with joker valve in it the dirty water floods back down the pipe all over the floor as you cant easily get a bucket under it!
Any tips?
Charles
 
Did mine last month, for only the second time in ten years. Obviously one should flush through lots and lots of water first, so the pipe post joker contains essentially just water and not gloop. Then have bucket and sponge ready to mop up the spillage quickly. I took three goes to get the new joker to seat itself perfectly with no leakage, so had to go through the whole process too often! All this in full Med heat, dripping with sweat, glasses fogged up, and usual impossible access requiring chimpanzee arms and fingers!! Next time will be quicker.

The old engineers trick before starting jobs like this was to stuff a smear of Vick or Tigers Balm up each nostril.
Peter
 
My top tip for catching 'water' is such circumstances is to use aluminium foil. Take a nice big sheet, double it up and mould it to form a cup under the fitting you're undoing and to create a gravity run-off drain into a suitable container where possible. Also works great for draining heat exchangers, exhaust manifolds, oil coolers etc.
 
I usually turn off the inlet valve, put fresh water with some disinfectant in the bowl and pump a little past the joker. Leave for a while before starting work and then pump lots of fresh through via the bowl. Lever is obviously in drain position instead of flush. A few extra pumps to displace as much water as possible and that's it. Water will still leak out when changing the valve but at least it is reasonably clean.

Change the flap valve at bottom of the cylinder if you have a twist and lock model. That valve stops water running back much more effectively than the joker valve. It seats into a fine ridge on the base, so give that a good clean before assembling.

Beaten to it by Resolution. Wifi signal dropped and my earlier reply vanished. Pasted this post when connection came back. Good tip about aluminium foil.
 
Steve_N said:
My top tip for catching 'water' is such circumstances is to use aluminium foil. Take a nice big sheet, double it up and mould it to form a cup under the fitting you're undoing and to create a gravity run-off drain into a suitable container where possible. Also works great for draining heat exchangers, exhaust manifolds, oil coolers etc.
Click to expand...

I carry a small packet of disposable nappies for such spills - including around the log impeller when removing or when cleaning the filters--
 
houldsworth said:
Got to replace this valve as loo keeps backfilling.
Presumably as you undo the outlet fitting with joker valve in it the dirty water floods back down the pipe all over the floor as you cant easily get a bucket under it!
Any tips?
Charles
Click to expand...

Yes, 'water' gets all over the floor... (LOL: thousand yard stare creeps in at this point...)

So: (1) Buy a new joker valve.
(2) Sling a few bucketfulls of fresh or mild bleach detergent water down your loo and pump it through on the 'empty pan' setting. Your 'water' in the soil pipe really now is water.
(3) Take two or three old cotton duvet covers and some spare towels you never use and stuff them around the front and back of your loo.
(4) Undo the two screws that retain the joker valve. Water will come *issing out and be absorbed by the duvet covers/towels. Mop up and remove these to the cockpit ASAP.
(5) Change the Joker valve. Screw the two screws back up evenly and tight. Sling a bucketful of water down the loo to check for water tightness (better it's fresh water that leaks...)
(6) Resume use of your loo.
(7) Put old duvet covers into your home washing machine/pass them to your wife, etc
(8) Dispose of old joker valve. Remember where it has been and wash your hands appropriately.

Simples, and yes: this is based upon experience of inverted joker valve (where Mrs LL hadn't opened the 'out' seacock first.
The pipe all the way to the vacuum break was full of, er, not water...)
 
The clearance between my joker valve and the toilet base is only about an inch. I can get a decent polythene bag beneath the housing, which catches most of it. Once the housing is separated the hose connecting it and the toilet is loose, so the bag can be removed easily. Living aboard for half the year I expect to change mine at least once per year but things happen and some years it could be four or five.
 
vyv_cox said:
The clearance between my joker valve and the toilet base is only about an inch. I can get a decent polythene bag beneath the housing, which catches most of it. Once the housing is separated the hose connecting it and the toilet is loose, so the bag can be removed easily. Living aboard for half the year I expect to change mine at least once per year but things happen and some years it could be four or five.
Click to expand...

Best type of bag for this is a ziplock, the type that has the little blue slider. The insert at top makes it easier to use.

N.B. Jabsco Greco and Raritan joker valves are interchangeable. Jabsco usually the cheapest.
 
Last edited:
Mistroma said:
I usually turn off the inlet valve, put fresh water with some disinfectant in the bowl and pump a little past the joker. Leave for a while before starting work and then pump lots of fresh through via the bowl. Lever is obviously in drain position instead of flush. A few extra pumps to displace as much water as possible and that's it. Water will still leak out when changing the valve but at least it is reasonably clean.

Change the flap valve at bottom of the cylinder if you have a twist and lock model. That valve stops water running back much more effectively than the joker valve. It seats into a fine ridge on the base, so give that a good clean before assembling.

Beaten to it by Resolution. Wifi signal dropped and my earlier reply vanished. Pasted this post when connection came back. Good tip about aluminium foil.
Click to expand...

not quite sure what you mean by the 'flap valve at bottom of cylinder'.
looking at parts list diagram on web jabscoshop.com it is not clear to me which this valve is!
joker valve is clearly named.
boat in Poros, me in UK at present so can't tinker easily.
Charles

ps. all comments most helpful and appreciated.
 
The backfilling problem is almost impossible to solve if you have a holding tank mounted above the toilet because this gives you a head of water. Joker valves are completely incapable of stopping backflow in that situation. If you hold a brand new one up to the light you will see through it, so it has no chance. The flap valve can seal, but if the toilet is old and there is any limescale on the seating it will also leak. The lock down type can even make things worse because it can actually distort the rubber flap enough to unseat it.

The fact is that the Jabsco Toilet is reliable and avoids backfilling if the output goes downhill to a seacock, but they are not really designed to pump out uphill. When I go to my boat at the end of this month I am going to fit a non return valve into the output hose a few inches from the joker valve in the hopes that I can solve the problem, which was not solved even after completely stripping the toilet and dissolving all of the limescale with acid and fitting new joker and flap valves.
 
Our holding tank is above the pump but our system, which is gravity-emptied, includes a seacock type valve to hold or divert effluent from the tank. For ordinary use, this is kept closed. Joker valves are pretty unreliable and we limit the chance of back flow by pumping "dry" until most of the pipe contains air. This also obviates the need for a syphon break.
 
Norman_E said:
The backfilling problem is almost impossible to solve if you have a holding tank mounted above the toilet because this gives you a head of water. Joker valves are completely incapable of stopping backflow in that situation.
Click to expand...

I'm afraid that's not true. My Jabsco pumps uphill about a metre to the top of the holding tank, and I don't get backflow at all.
 
when we installed a new Twist'nlock Jabsco our local loo guru recommended fitting an additional check valve in the line to the holding tank, since our vertical and gravity draining tankfills from top down andthe filler connection is over 4ft above the toilet itself. We have no drain back at all and could change the joker or ducks bill valve as they call it here with dry feet.[/SMUG]
 
Norman_E said:
The backfilling problem is almost impossible to solve if you have a holding tank mounted above the toilet because this gives you a head of water. Joker valves are completely incapable of stopping backflow in that situation. If you hold a brand new one up to the light you will see through it, so it has no chance. The flap valve can seal, but if the toilet is old and there is any limescale on the seating it will also leak. The lock down type can even make things worse because it can actually distort the rubber flap enough to unseat it.

The fact is that the Jabsco Toilet is reliable and avoids backfilling if the output goes downhill to a seacock, but they are not really designed to pump out uphill. When I go to my boat at the end of this month I am going to fit a non return valve into the output hose a few inches from the joker valve in the hopes that I can solve the problem, which was not solved even after completely stripping the toilet and dissolving all of the limescale with acid and fitting new joker and flap valves.
Click to expand...

I believe almost exactly the opposite. Yes, there is a gap between the lips of some new joker valves but the head of water closes them fully. The typical loop of a toilet discharge will always provide a head of water above the joker valve, not sure how many toilets discharge downhill to the seacock but I suggest it is not many. My holding tank is well above the joker valve but since the discharge from the toilet goes via a loop above the tank its position is immaterial.
 
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