Jabsco Macerator - worse than just unreliable

[send54sail]

I have a newish (less than 12 months old) Jabsco macerator pump 18590 – 2092 (12 volt). Its the 3rd or 4th one I have bought in the last 6 years so I was under no illusions about the disgraceful quality of these products, despite the high price (and forums are full of caustic comments about them), but I wonder if anybody has come across the following issue?

First, the macerator has not successfully emptied the holding tank on the last couple of times that I have attempted to use it (even though the motor ran as usual, and sounded normal), so yesterday I decided to check what the problem was.

Before taking anything apart, the first thing I did was to get the holding tank emptied out at a boat pump-out facility at the marina so that I could inspect the macerator without the contents of the holding tank spilling out. However, when I opened up the lid to the holding tank itself (which had only just a few minutes earlier been completely emptied at the pump-out) I found the holding tank was filling up very fast with sea water. I then shut the seacock straightaway (which obviously I would have done before removing any hoses, but hadn't expected any drama just from lifting he holding tank lid).

To double check, with the seacock closed, I then removed the hose from the inlet side of the macerator (i.e. exposing the 1 1/2 ” plastic "hose tail" piece on the end of the macerator that the hose is clipped to that connects the macerator to the holding tank). When I then allowed the seacock to open for a few moments with that hose removed, seawater again poured out of that inlet side of the macerator.

I realise now that, not only had the macerator not been working to pump the holding tank out, but, much more dangerously, seawater in the outlet pipe (i.e. the 1” hose that connects the macerator the seacock) was actually being allowed to pass through into the “holding tank-end” of the pump. This means that it was only the tight lid on the holding tank that prevented the boat from being flooded (and sunk). Obviously, the macerator should not allow water to pass in the direction from “seacock-end” to “holding tank-end” – it should only allow flow in the opposite direction.

If I had left the boat for an extended period then there would have been constant flow of seawater into systems (ie. the holding tank itself) which are not designed to deal with seawater coming in under pressure and inevitably the boat would have been at risk of sinking.

Any thoughts on this situation gratefully received - including any different brand to replace the Jabsco macerator pump 18590 – 2092.

Cheers
Andy

 

[matthewriches]

I'm not a plumber but I have a Whale Gulper. Sucks it from the tank, chews it up and pushes it out. I'd guess you'd want a loop thingy as well?

 

[matthewriches]

It wasn't Whale, it is Jabsco's version.

 

[RichardS]

I cannot believe that the macerator is designed to act as a non-return valve .... and, even if it was, there is no way that any holding tank system would be designed to rely on that valve holding. I'm pretty sure that there must be something wrong with the design of your system. Possibly a missing swan-neck or anti-syphon loop?

Richard

 

[pvb]

I cannot believe that the macerator is designed to act as a non-return valve .... and, even if it was, there is no way that any holding tank system would be designed to rely on that valve holding. I'm pretty sure that there must be something wrong with the design of your system. Possibly a missing swan-neck or anti-syphon loop?

Correct. The Jabsco macerator pump has no backflow protection; the OP's system needs re-designing.

 

[vyv_cox]

The exploded diagram of this pump suggests it is a vane pump with a rubber impeller. This should act as a non return valve
, which suggests it may be broken or faulty. However, it seems the installation could be better designed.

 

[emmalina]

My last Jabsco lasted 5 years Only then did the impeller give up. Any system that uses an impeller pump as a non return valve is in deep trouble ! Where the hell is the vented loop ? Oh and they (like any impeller pump) don't like to be sat a long time without use ! Back to the drawing board me thinks.

 

[Momac]

I have the same pump which was replaced 4 years ago when the boat was 11 years old and no issues since. It had developed a slight leak and at the time was easier to fit a new pump rather than try a repair. From a quick Google search the price seems to have gone up substantially since 4 years ago.

I have the sea cock normally closed on the outlet so there can be no pressure on the pump from the sea water side. My tank, or at least the top of the tank is above the water line. I am fairly sure the sea water doe snot flow back in the time between stopping the pump and closing the sea cock - or at least there must be no substantial flow.

The environment is as harsh as it gets .

Is a service kit not available for the pump?

 

[VicS]

I have a newish (less than 12 months old) Jabsco macerator pump 18590 – 2092 (12 volt). Its the 3rd or 4th one I have bought in the last 6 years so I was under no illusions about the disgraceful quality of these products, despite the high price (and forums are full of caustic comments about them), but I wonder if anybody has come across the following issue?

...............................

Any thoughts on this situation gratefully received - including any different brand to replace the Jabsco macerator pump 18590 – 2092.

Cheers
Andy

What Vyv says may be true about ordinary flexible vane pumps acting as their own nrv, but it seems that this one probably does not and has not been installed as described in the instructions which state

NOTICE: The discharge thru-hull may be positioned
below the waterline only if the discharge hose has a
vented loop fitting installed at least 8" above the waterline
at all angles of heel or trim. Consult with a qualified
marine plumber​

In full, with expanatory diagrams, here:

https://www.absak.com/pdf/manuals/Flojet/18590man.pdf

.

 

[fontmell]

Hi All

Why don't you tallk to the very helpful jabsco rather than just winge on here! You will learn the pump needs servicing as the impellor expands when constantly immersed, you will learn that the impellor will not act as sea cock, you will learn that thousands are sold and the main problem is nearly always to do with what is in the holding tank (Chemicals) degrading the impellor. I have a 12 year old version in heavy commercial use and change impellor every couple of years.

 

[vyv_cox]

I was not suggesting that a vane pump was an adequate nrv for the purpose, only that in the OPs case it would appear to be absent. An engine seawater pump will hold a head of water for an appreciable time.

 

[VicS]

I was not suggesting that a vane pump was an adequate nrv for the purpose, only that in the OPs case it would appear to be absent. An engine seawater pump will hold a head of water for an appreciable time.

The pump body, esp the inlet port looks quite different to other flexible vane pumps eg engine cooling water pumps .

Perhaps this is why it wont hold back much of a head... and the note in the installation instructions as result.

Surprising perhaps that they dont fit it with a Joker valve.

 

[npf1]

One wonders why the seacock is left open at any other time apart from when emptying the tank.

I ran a system for many, many years where the macerator and outlet were both below the water line and there was no vented loop. I only ever opened the seacock to run the pump, and closed it again immediately. I did have pump issues several times but they were either due to hair from the showers, or something that shouldn't have been put down a bog or sink. All the boat's waste (bogs/showers/sinks) went into two holding tanks there was a redundant pump in the outlet loop, so whenever there was a pump issue, it was rarely an urgent issue.

 

[thinwater]

One wonders why the seacock is left open at any other time apart from when emptying the tank.

^^ This. A loop is also needed, but why leave unused seacocks open? Surely the pump is not used for days at a time (in the US it could be months or years, since inside 3 miles and all bays (even huge ones) you must use shore pump-outs). Was the lack of backflow prevention causing the OP to run the pump daily or more, explaining the short life?

 

[MoodySabre]

Not quite the same as my macerator pumps out through the loo seacock (via a Y connector) which goes way above the waterline. However I found recently that pumping out direct was filling the tank.. I deduced that there is a restriction in the outlet pipe ( lime scale build up) and so the waste took the path of least resistance back through the macerator into the tank. I am leaving the diverter on to the tank and pumping it out often. New hose is now on the list of jobs -a grim job on a Moody 31.

 

[vyv_cox]

The pump body, esp the inlet port looks quite different to other flexible vane pumps eg engine cooling water pumps .

Perhaps this is why it wont hold back much of a head... and the note in the installation instructions as result.

Surprising perhaps that they dont fit it with a Joker valve.

View attachment 71827

I agree, the axial suction may provide more of a leak path than is available with a radial one but would have thought that the vanes would mostly stop the discharge port.

 

[send54sail]

Thanks for all the thoughts chaps. The Macerator was accepted as defective and was replaced. However, I'm still interested in why these items have such a short lifespan since I am now on my third in 4 years. Obviously, i only ever opened the seacock when actually using the pump but - because the pump and the hose to the seacock are entirely below the waterline - the pump would still be sitting in water (sea or foul or a mixture) all the time and it doesnt seem to be well made enough to withstand that without breaking down (and in my recent case even allowing water to flow back into the holding tank etc).
If I was able to put a vented loop in the run from pump to seacock then i assume that would create the desired water-free zone at the pump itself (and hopefully it might last longer than a few months?) but on my boat the whole run is below the floor, which is itself below the waterline, so I cant fit a loop in there which would go higher than the waterline (at least not without redesigning the whole thing). So, a combination of the design not allowing a vented loop plus Jabsco kit not being able to cope with being immersed seems to be pretty problematic. Am i missing something?
Thanks for the insights!
All the best

 

[thinwater]

Is there any chance the pump is running dry, either after the tank is empty or because of inlet clogs? Running dry will ruin the impellor in seconds to minutes, depending on extent. Did you examine the interior of the pump to determine the type of failure? Pictures?

* Is someone flushing facial tissues? This will cause clogs. Remove them from the head.
* Is there some factor in the inlet design, perhaps a 90 el too close to the pump, that is causing trouble.
* Are you using a treatment chemical? Which, and how much?
* Are you winterizing the head with glycol? Propylene glycol can ruin flexible impellers.
* Are the impeller vanes stiffened or cracked? If yes, is it heat or chemical damage?

I believe there is a factor you have not yet identified.

 

[langstonelayabout]

I used to own a boat with one of these fitted in the end of the holding tank, with a slightly over 20cm loop of 1" pipe to the exit seacock. No vent.

It was properly stuck when I bought the boat so instead of splashing out GBP 210 for a genuine one I went to a chandler in the midlands that sold me a non-Jabsco macerator pump for just over GBP 70. It failed after 1 year of occasional, very light use. (maybe that is half the problem)

Keeping a significant electrical component below the waterline fixed to a tank full of seawater and pee is little short of stupidity in extreme/design. Had I have kept the boat I would have replaced it with a manual pump.

A total piece of rubbish, and, honestly, you would be better fitting a gravity holding tank to a small yacht: it needs no electricity and less servicing.

 

[RupertW]

^^ This. A loop is also needed, but why leave unused seacocks open? Surely the pump is not used for days at a time (in the US it could be months or years, since inside 3 miles and all bays (even huge ones) you must use shore pump-outs). Was the lack of backflow prevention causing the OP to run the pump daily or more, explaining the short life?

For me the seacocks are opened the moment we get on the boat and closed only when we leave it weeks or months later, or when using the holding tank, until it can be released when we next leave a bay. I wouldn't switch off the mains water at my house in between using the dishwasher or taps or toilets and wouldn't do the same on a boat either.

In the areas I sail nobody every pumps out - in the UK people often don't have holding tanks at all in anchorages or harbours because the water is too cold and murky to go swimming, but in Med and Caribbean dumping your waste at sea from the holding tank is the norm, and harmless especially if following the civilised Greek way of nothing down the loo that hasn't been eaten.




Sailing in the UK and Med (and Caribbean occasionally) the