Jabsco problem- bowl not filling

[sparkie]

Hi all, sorry to add to the mountain of previous on these things but I'm hoping to save a bit of time wading through all the threads. After being faultless for 5 years or more my Jabsco won't suck water in. Hull inlet is clear, and when filled with a bucket the bowl pumps out fine, so not the pump plunger seal methinks? Any suggestions before I get the rubber gloves on? Cheers S.

 

[LadyInBed]

Try taking off pump housing top and cleaning the (2) flap valves, and check the in / out leaver operation.

 

[prv]

Do you normally leave the lever in the "wet" or "dry" position?

Intuitively it seems sensible to leave it on "dry", to prevent water coming in. This is actually wrong, because the lever works by distorting the flap on the intake valve to stop the pump working. If you leave it there all the time, the distortion becomes permanent and then the pump stops working regardless of the lever position. It's better to leave it on "wet" to allow the flap to close properly - if anything this actually provides slightly more protection against incoming water.

Pete

 

[VicS]

Whats said above. Check / overhaul the flap valves in the top section of the pump,


Exploded diagrams and parts lists on the Jabscoshop website will be useful.

Take care to engage existing screw threads in plastic parts when reassembling.

 

[rob2]

No, it is rubber glove time. The flap valves may have got stuck on their seats or simply aren't seating at all. You're not looking for a leaking gasket, just a valve that's not doing the biz. It's quite possible that cleaning and reassembling will sort it out, but you may as well buy a service kit and leave it aboard if not used - for next time. I've usually found all the rubber valves are either slightly encrusted or slimy depending on their position and can often be simply wiped cleam or scraped off with a plastic squeegee (sp?).

Take great care locating the thread with the body screws or you'll be buying a new loo - they're self tappers into plastic. When repriming the pump, sometimes it will fail to tackle the task, if you drop the inlet syphon loop down to inlet level it eliminates the head pressure. Once primed, the pump can easily pump up over the loop.

Rob.

 

[catalac08]

These things are so simple that there is little to go wrong. The water sucked in is on the top of the piston on the downstroke and is then lifted into the bowlby the upstroke. If you take off the top 6 scews and remove the plunger it is very apparent if the rubber flap is complete or has deteriorated. There is nothing at the bottom to do with sucking water in so the really grim part of the pump can stay assembld! When you move over the lever to allow water in there is a plastic stub that can become worn or the little rubber flaps with weights can detatch or the small spring can become displaced.

I spent about a day recently with the same problem and that turned out to be a blockage in the inlet thro hull fitting that allowed water to pour out so I initially thought it was ok but it would still not allow sucking in, perhaps a dead fish, plastic bag etc. I blew out the inlet tube with a dinghy inflator and all was then well. Good luck-a horrible job.

 

[johnalison]

It's better to leave it on "wet" to allow the flap to close properly - if anything this actually provides slightly more protection against incoming water.

Pete

Although I agree with your advice, it hasn't been my experience that the "wet" position will prevent water ingress. I have fitted a syphon break on the inlet side for this reason, otherwise the bowl will fill to near the brim.

 

[prv]

Although I agree with your advice, it hasn't been my experience that the "wet" position will prevent water ingress. I have fitted a syphon break on the inlet side for this reason, otherwise the bowl will fill to near the brim.

Agreed, it won't really, but the point is that it's no worse at it than the "dry" setting.

Pete

 

[sparkie]

Thanks all. Always been careful to leave the lever in the recommended position, so all a bit puzzling. Anyway, comforted by the fact that I may not have to strip the thing out completely- it's a pig to get out. Lots of sound advice as usual, I'll attack the top next week when I'm back down there. CHEERS! S.

 

[RichardS]

Do you normally leave the lever in the "wet" or "dry" position?

Intuitively it seems sensible to leave it on "dry", to prevent water coming in. This is actually wrong, because the lever works by distorting the flap on the intake valve to stop the pump working. If you leave it there all the time, the distortion becomes permanent and then the pump stops working regardless of the lever position. It's better to leave it on "wet" to allow the flap to close properly - if anything this actually provides slightly more protection against incoming water.

Pete

I've recently installed a new Twist and Lock Regular and the instructions are very specific that after use the seacocks must be closed and the flush control left in the shut (right hand) position rather than the flush (left hand) position.

Have you taken the valve fitting to pieces to confirm your recommendation Pete, as I have never removed the cover plate.

Added one month later ..... I have now installed a second Jabsco and dismantled the pump head on the old one to understand the mechanism. I can confirm that Pete is correct and that the valves are held in the "unstressed" state if the flush control is left in the flush (left hand) position. I will ignore the Jabsco instructions from now on! Thanks Pete.

Richard

 

[ghostlymoron]

After 5 years, I would renew the valves and seals. A service kit costs about 30£

 

[Scotty_Tradewind]

Whats said above. Check / overhaul the flap valves in the top section of the pump,


Exploded diagrams and parts lists on the Jabscoshop website will be useful.

Take care to engage existing screw threads in plastic parts when reassembling.

as above BUT Don't overtighten those screws ..... stainless screws into plastic base .... only one winner if too tight!

Have you looked into cost of replacing pump housing complete. If you then recondition you will have a spare.

S.

 

[lpdsn]

After 5 years, I would renew the valves and seals. A service kit costs about 30£

I've always thought that a bit steep considering a complete new pump assembly costs £80. Buy a whole new pump and you can cannablise the old one for spares.

 

[ghostlymoron]

I've always thought that a bit steep considering a complete new pump assembly costs £80. Buy a whole new pump and you can cannablise the old one for spares.

Agree its expensive for a few bits of rubber but it does solve the problem and only works out at £6 per year. If you keep buying new pumps, sooner or later you'll need to the little flap valves to get them serviceable.