Jabsco Macerator Pump - Seven Years Later

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November 2010 -- Gee, it's been seven years to the month since I installed the macerator pump. I've really only been using it hard since moving aboard two years ago, though.

This is a critical pump, because I did not plumb the boat for direct overboard discharge. Everything goes into the tank,
and gets pumped out when I'm off shore.

For about a year, it's been worrying me. It had a hard time priming itself, and often would run for about 15 seconds and then the breaker would flip. It seemed to be able to work when my battery charging system was in 'acceptance' mode, which produces charging voltage in the 14.5 volt range. The higher voltage seemed to feed the motor better, and it was able to power through whatever the problem was.

That was a clue, but it was confusing. It's a short wire run and I used 12 gauge wire, so there couldn't be much of a voltage drop to the pump.

It was possible that the hoses were getting clogged with calcification. There's a reaction between urine and sea water that can create a calcium carbonate buildup inside the hoses, reducing the inside diameter and making it harder to move material through the hoses. So, with an empty tank, I pumped five gallons of vinegar through the head and let it sit for a week, adding another gallon every day. The vinegar will react with the buildup in the hoses, and dissolve it.

I saw, and heard, a lot of bubbles due to the chemical reaction with the vinegar. A lot of crusty stuff came loose in the one foot pipe between the bowl and head pump, so there was definitely some buildup in the hoses.

But still the macerator pump failed to prime, and flipped the breaker.

I really didn't want to pull the pump out, as I still remember what a royal pain it was to install it the first time.

So I decided to check the brushes. After all, the motor brushes could be getting worn and dusty, and the dust could be stealing power from the motor through weak short circuits or poor contact. I got my water maker pump working again by cleaning the brushes, and figured it was worth a shot.

Bad idea. Unlike my water maker pump, and the fresh water pressure pump, this macerator pump has a sealed bearing that's pressure fit onto the motor shaft at the bottom. It makes sense, after thinking about it, since this motor really has to work hard sometimes and there can be a lot of twisting torque applied to the working end.

That bearing prevented the bottom cap from coming off the motor, and although I tried to force it off while the motor was still mounted under the head sink, I only managed to wreck the motor.

Bottom line: You can't check, clean, or replace the brushes on my macerator pump, and trying to do it will wreck the motor.

Fortunately, I have a spare.

The old pump came out much easier than I'd expected.
I am really glad that I used the expensive Shields hose fittings for the stiff Sealand Odorsafe hose. A normal barbed fitting would have been jammed into the hose so tightly that I would have had to cut the hose to get it off, but the smooth Shields fitting allowed me to work the hose off with a minimum of cursing.

I'm also glad that my spare macerator pump is the exact same model as the old one. I can take the entire cap assembly, with the PVC pipe fittings in place, and move it onto the new pump. What a relief.
It's just a replacement, not a redesign of the entire setup.

I originally went with the Jabsco pump because it allowed me to move the top assembly, and change the direction of the hose connections. That is essential if one is to reduce the amount of hose winding around in the head. Less hose means less material sitting in the hose, which means less stuff permeating the hose, which means less odor.
My hoses are seven years old now, but there's no hint of smell.



Somebody put something in the head that had *NOT* passed through his or her body.

I don't know what it is, but it's very fibrous and tough, almost like cloth. It nearly covered the blades and was wrapped around the motor shaft. Well, that explains why the pump was having a hard time priming itself, and why the motor would slow down and stall, flipping the breaker.

This is my fault, as I've allowed toilet paper to be put in the head. The pump can macerate paper. I only use the cheapest, weakest paper.
I usually have found the 'septic tank safe' paper,
that dissolves into pieces very quickly.

However, by allowing *anything* to go in that had not passed through the human body, I allowed guests to interpret the exception to the rule. I have a feeling that this fibrous cloth is a 'Wet One.'
I keep Wet-Ones in the head.

So I'm going back to the Absolute Rule: Nothing Goes In The Head Unless It Passes Through Your Body First. I've reinstated the collection of old plastic grocery bags, and paper products go into the bag, are tied up tightly, and placed in the trash.

If anyone doesn't like that, he or she can go sail on some other boat.


If I hadn't already destroyed the motor, I could have cleaned this up, rebuilt it and put the old pump back.

It's too late for that.

The new pump has four cutting blades instead of two. I guess that's better. Other than that, it's a perfect match for the old one.

I took it apart anyway, and lubricated everything well with silicone grease. It only took a couple of hours to reinstall.


As with all my electrical connections, these were done with good Ancor butt connectors, and then completely sealed with adhesive lined heat shrink tubing.

This is installed in the head, after all, and there's a shower here.

Besides, I'll occasionally take a hose and wash out the entire inside of the hull. So every electrical connection on the boat is waterproof.



Since the old motor was wrecked, I decided to take a good, destructive look at it.

I never could get the bottom plate completely off. The bearing was a really tight fit. However, here's a good look inside.

Everything is really clean, with no problems at all. You can see one of the brushes (which fell out of it's little holder) and it's clean.


Here's another look at one of the brushes, pulled out from inside.

There's plenty of material left after two years of hard use. It's a much bigger, thicker brush than the ones on my water maker and fresh water pumps.

This pump would have been good for another five years or more, if I hadn't destroyed it trying to fix it.

Oh well.


Here's the top of the motor. The impeller (not shown) was in perfect condition.

There was some tarnishing of the brass bolts that hold the entire top pump assembly together, but nothing serious.

Having the pump mounted with the motor under the wet pump assembly doesn't seem to have created any problems. No liquid matter had leaked through the seals around the motor shaft, and the motor itself was as shiny and new as the day I installed it, seven years ago.

Overall, I would recommend this pump to anyone who asks.



Just for my own documentation, here's the part number of the motor.




And here's the part number for the entire Jabsco pump.