Jabsco toilet - strange flush resistance

[LiftyK]

In brief, any reason why my Jabsco twist and lock with new pump
- pumps out normally
- resists pumping out when the flush position is selected

The background

- the loo pumps everything into a holding tank. There is no diverter to select between tank and sea.
- the loo was working normally for years and then started to emit a dribble at the top of the barrel where the plunger goes in
- my plan was to remove the entire pump section, replace it with a new pump then service the old pump assembly and keep it on standby as a spare
- the only unusual thing I did when installed the new pump was to liberally apply silicone grease to the piston rubber

Upon testing the new setup, I found that
1. With the selector switch set to the right, pump out only, everything was perfect and no more leak. The handle moved up and down very easily.
2. With the selector set to the left, to flush and pump out, water was sucked in on the upstroke. Not a huge amount but it seemed normal. The effort required on the upstroke felt about right.
3. With the selector still to the left, the downstroke offered a lot of resistance. The piston wanted to bounce back near the bottom of the downstroke.

The flush setting downstroke has eased marginally over time, at least in my imagination. However I don’t understand how the handle is really easy to operate when pumping out the bowl but as soon as the selector is set to flush the downstroke offers so much more resistance.

Any ideas please?

 

[Boater Sam]

In brief, any reason why my Jabsco twist and lock with new pump
- pumps out normally
- resists pumping out when the flush position is selected

The background

- the loo pumps everything into a holding tank. There is no diverter to select between tank and sea.
- the loo was working normally for years and then started to emit a dribble at the top of the barrel where the plunger goes in
- my plan was to remove the entire pump section, replace it with a new pump then service the old pump assembly and keep it on standby as a spare
- the only unusual thing I did when installed the new pump was to liberally apply silicone grease to the piston rubber

Upon testing the new setup, I found that
1. With the selector switch set to the right, pump out only, everything was perfect and no more leak. The handle moved up and down very easily.
2. With the selector set to the left, to flush and pump out, water was sucked in on the upstroke. Not a huge amount but it seemed normal. The effort required on the upstroke felt about right.
3. With the selector still to the left, the downstroke offered a lot of resistance. The piston wanted to bounce back near the bottom of the downstroke.

The flush setting downstroke has eased marginally over time, at least in my imagination. However I don’t understand how the handle is really easy to operate when pumping out the bowl but as soon as the selector is set to flush the downstroke offers so much more resistance.

Any ideas please?

Lime scale in the discharge pipe?

 

[stranded]

In brief, any reason why my Jabsco twist and lock with new pump
- pumps out normally
- resists pumping out when the flush position is selected

The background

- the loo pumps everything into a holding tank. There is no diverter to select between tank and sea.
- the loo was working normally for years and then started to emit a dribble at the top of the barrel where the plunger goes in
- my plan was to remove the entire pump section, replace it with a new pump then service the old pump assembly and keep it on standby as a spare
- the only unusual thing I did when installed the new pump was to liberally apply silicone grease to the piston rubber

Upon testing the new setup, I found that
1. With the selector switch set to the right, pump out only, everything was perfect and no more leak. The handle moved up and down very easily.
2. With the selector set to the left, to flush and pump out, water was sucked in on the upstroke. Not a huge amount but it seemed normal. The effort required on the upstroke felt about right.
3. With the selector still to the left, the downstroke offered a lot of resistance. The piston wanted to bounce back near the bottom of the downstroke.

The flush setting downstroke has eased marginally over time, at least in my imagination. However I don’t understand how the handle is really easy to operate when pumping out the bowl but as soon as the selector is set to flush the downstroke offers so much more resistance.

Any ideas please?

Interesting - we have a similar issue with a new jabsco pump assembly we bought in the spring - symptom sounds identical except ours is when the lever is over to empty. It is fine if you physically hold the lever hard over to the right while you pump, otherwise judders and kicks back. Might have been quality control issues on the levers/changeover valves in a batch of pumps?

 

[KevO]

Interesting - we have a similar issue with a new jabsco pump assembly we bought in the spring - symptom sounds identical except ours is when the lever is over to empty. It is fine if you physically hold the lever hard over to the right while you pump, otherwise judders and kicks back. Might have been quality control issues on the levers/changeover valves in a batch of pumps?

Ours has started to do the exact same thing... was planning to strip it down on next Visit. It was serviced at the start of the season with
all bits replaced and worked fine until our last trip.

 

[LittleSister]

Inlet seacock closed, or blocked, perhaps?

Inlet and water transfer to bowl pipes reversed?

 

[VicS]

What LittleSister suggests.
Some restriction in the inlet/flush plumbing.

 

[KevO]

Inlet seacock closed, or blocked, perhaps?

Inlet and water transfer to bowl pipes

 

[KevO]

Nope, not in mine, well, not when serviced in March anyway, all pipes checked as clear and seacocks serviced too. I'll strip it down again and see.

 

[jaminb]

is the selector pushed over fully - mine has resistance if not.

 

[KevO]

is the selector pushed over fully - mine has resistance if not.

Yes but sometimes it flicks back a mil or so and has to be held over to the right.

 

[mikegunn]

Seawater inlet blocked by weed. Not uncommon this time of year.
If you have a seawater inlet filter fitted, that may be blocked.

Mike

 

[KevO]

Seawater inlet blocked by weed. Not uncommon this time of year.
If you have a seawater inlet filter fitted, that may be blocked.

Mike

Seawater pumps in perfectly. It's on the empty switch position the prob occurs.

 

[mikegunn]

Seawater pumps in perfectly. It's on the empty switch position the prob occurs.

Sorry, my response was to the OP’s problem, not yours. I should have made that clear.
Mike

 

[stranded]

Ours has started to do the exact same thing... was planning to strip it down on next Visit. It was serviced at the start of the season with
all bits replaced and worked fine until our last trip.

Given they are so inexpensive I was planning to just get another when we get back to the UK, but happy to add our experience to a joint complaint if anyone wants to make one - imagine jabsco will be reasonable.

 

[LiftyK]

Lime scale in the discharge pipe?

Good theory but when the pump is simply emptying the bowl it uses the same pipe to discharge as it does when in the flush setting.

 

[LiftyK]

Interesting - we have a similar issue with a new jabsco pump assembly we bought in the spring - symptom sounds identical except ours is when the lever is over to empty. It is fine if you physically hold the lever hard over to the right while you pump, otherwise judders and kicks back. Might have been quality control issues on the levers/changeover valves in a batch of pumps?

What a coincidence. Thank you for sharing your experience. The black selector lever is definitely hard over one way or the other so it is not that. Maybe a bad batch indeed. I bought my pump around the same time as you did.

 

[LiftyK]

Ours has started to do the exact same thing... was planning to strip it down on next Visit. It was serviced at the start of the season with
all bits replaced and worked fine until our last trip.

Mine is fairly new. However, with the shared experiences in this thread I have enough confidence to contact Jabsco and ask for their advice.

 

[LiftyK]

Inlet seacock closed, or blocked, perhaps?

Inlet and water transfer to bowl pipes reversed?

In my case, all was working well with the old pump. Changing to the new pump with no change to the pipes. Furthermore, when the bowl empties it goes straight to a tank. No seacock is involved.

Similarly, the up stock to bring in seawater works ok. It is only the downstroke that resists, and only on the flush setting.

 

[LiftyK]

is the selector pushed over fully - mine has resistance if not.

Yes, I checked that but will try again

 

[LiftyK]

Seawater inlet blocked by weed. Not uncommon this time of year.
If you have a seawater inlet filter fitted, that may be blocked.

Mike

The flush water comes in with minimal resistance. Only the downstroke gives resistance.

Sorry, my response was to the OP’s problem, not yours. I should have made that clear.
Mike

OP (me) had the same symptoms as mikegunn