Macerator pump failure?

My 11 year-old Jabsco macerator pump took a dump . I pulled it, and found the motor full of water. I am now rebuilding the pump (again)and thinkin' the failure was due to the holdin' tank vent vent bein' plugged with the pump workin' against a solid head, ergo the water inclusion. Any thoughts out there?

I doubt it. My guess is that the seal failed or you did something wrong the last time you rebuilt it.


My thought is, once you consider the cost of the rebuild kit and the fact that you have to remove and replace the pump, it makes sense to install a new pump. If you want to rebuild the failed one anyway, carry it as a spare.

If you look at the exploded drawing on page 3 of the manual Jabsco Macerator Pump owner manual you'll see that MOTOR (part 11) is sealed. If water gets into it, it couldn't run. It's the pump assembly--the impeller and assorted seals and gaskets that filled up with water, but if it were working against a blocked tank, the motor would just overheat and shut off.

Your macerator pump is 11 years old...at least twice the average lifespan of a Jabsco macerator. A service kit for it is about $50...you can buy the whole thing for about $100. You've already put $50 into it...if you rebuild it again--and btw, I'm pretty sure you've rebuilt the pump (parts 5-7 in the drawing), not the motor--rebuilding a pump that old again would be throwing good money after bad. Replace the macerator pump!

If your tank vent is blocked, you're lucky that you weren't at a pumpout...'cuz a strong pumpout pulling against a blocked vent can implode a tank. So make sure your tank vent is clear before attempting to empty the tank again, or even using the toilet again...'cuz every time you flush against a blocked vent, you pressurize the tank...and that can have some very unpleasant consequences!

Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

ancora said:

Any thoughts out there?

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Yes, $hit can it and get a Sealand/Dometic diaphragm pump.

HeadMistress said:

If you look at the exploded drawing on page 3 of the manual Jabsco Macerator Pump owner manual you'll see that MOTOR (part 11) is sealed. If water gets into it, it couldn't run. It's the pump assembly--the impeller and assorted seals and gaskets that filled up with water, but if it were working against a blocked tank, the motor would just overheat and shut off.

Your macerator pump is 11 years old...at least twice the average lifespan of a Jabsco macerator. A service kit for it is about $50...you can buy the whole thing for about $100. You've already put $50 into it...if you rebuild it again--and btw, I'm pretty sure you've rebuilt the pump (parts 5-7 in the drawing), not the motor--rebuilding a pump that old again would be throwing good money after bad. Replace the macerator pump!

If your tank vent is blocked, you're lucky that you weren't at a pumpout...'cuz a strong pumpout pulling against a blocked vent can implode a tank. So make sure your tank vent is clear before attempting to empty the tank again, or even using the toilet again...'cuz every time you flush against a blocked vent, you pressurize the tank...and that can have some very unpleasant consequences!

Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

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Peggie,

Should we discover that the vent line is plugged, what's the best way to unplug it? Water? Air?

Giggitoni said:

Peggie,

Should we discover that the vent line is plugged, what's the best way to unplug it? Water? Air?

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It often gets plugged by insects at the thru hull. If that's the case, scrape them out with anything that's handy. Knife, stick, toothpick, etc.


Another real possibility is a clogged vent line filter. If the filter gets wet, it will probably clog. Personally, I would remove the filter and install a piece of hose in its place. The other option is to buy a replacement filter.

I pulled the motor apart and dried off everything with a heat gun. Replaced both bearings and the motor runs fine. I do not waste money on a rebuild kit every time it need rebuilding. I purchase the seals and impellers individually from a local chandlery. The bearings I got from an on-line bearing house 30 of them for $15.00. The gaskets I make my self. It costs me peanuts to keep the thing running.

My thoughts: is it really that much easier to type a ' instead of a g ? Last I looked, the g is much closer to the n on a keyboard...

If you have to keep spending those peanuts, not to mention the value of your time and effort, to keep it running, it doesn't sound to me like they're a very good investment. Everything has a lifespan...it's time to replace it unless you just want to keep throwing good peanuts after bad.

Should we discover that the vent line is plugged, what's the best way to unplug it? Water? Air?

You aren't gonna get out of this that easily...clearing a blocked tank vent requires some manual labor. However, like most things, prevention is a LOT easier than cure.

Vent line blockages typically occur in only two places--the vent thru-hull and the other end of the vent line...that end of the hose and the vent fitting on the tank. They rarely if ever occur anywhere else.

Start at the thru-hull...use a screwdriver blade, ice pick--whatever works--to scrape out anything that it's in it. If there's a screen, knock it out...screens create more problems than they solve or prevent. Then CAREFULLY open the cap on the deck pumpout fitting to relieve any pressure...you don't want to remove any hoses from the tank before doing this! Remove the vent line from the tank (warming the hose a bit with a blow dryer makes that easier)....scrape out whatever you find in either or both. Reconnect the vent line to the tank.

That SHOULD clear it. I also recommend that you replace the "vent" thru-hull with plain ol' bulkhead thru-hull--the kind you can stick your finger into...the same kind your sinks and bilge drain out of. This will allow you to prevent future vent blockages by simply sticking a hose nozzle up against it to back flush the line every time you wash the boat. Any critter that's taken up residence in it will just take a water slide ride into the tank. It's especially important to keep a close eye on the vent thru-hull in the spring, 'cuz that's favorite place for mud daubers to build a nest (I once had to clean one out of the venturi tube in the grill on my boat!)

NEVER overfill the tank! Waste builds up the tank fitting and that end of the vent line, creating a blockage. If you don't have a tank level indicator that lets you know how much is in the tank, install one!

Remove any vent line filter...they actually help to create the very problem they're sold to solve because they impede the flow of air in an out the vent line that's needed to keep a tank aerobic, which is the key to odor PREVENTION. Plus, they're expensive and are toast if they get wet--which makes it impossible to backflush the vent line to keep it clear. If your tank location or vent line installation makes impossible to use passive ventilation to keep the tank aerobic, some modification may work, or it may be necessary to install an aeration system. I'll be glad to help you work that out.

caltexflanc said:

My thoughts: is it really that much easier to type a ' instead of a g ? Last I looked, the g is much closer to the n on a keyboard...

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If a li'l ol' informal contraction upsets you enough to comment on it, my sloppy punctuation and slang contractions must give you chronic indigestion!

Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

I understand where ancora is coming from, a big part of his enjoyment comes from repairing what others would discard. Everybody enjoys this boating hobby a bit different from everyone else. Don't make it wrong just different.

That or he has a poop fetish.

CPseudonym said:

I understand where ancora is coming from, a big part of his enjoyment comes from repairing what others would discard. Everybody enjoys this boating hobby a bit different from everyone else. Don't make it wrong just different.

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I can see it, especially when you add the frustration that the pumps seem to go prematurely and the motors seem to last and last.

I repair-rebuild every motor I can.
As long as the winding are not shorted or open, motors can work again.
I even paint the insides with grey primer. In pool pumps with spun bearings, I have shimmed exterior bearing races with inserts made from SS sheet metal when they wore the housing.
Bearings and seal from a bearing company. You can buy rubber coated bearings and the little spring you can use a rubber oring if it is not SS.

I have repaired Lectra-San motors, macerator motors in Jabsco heads. Repaired Jabsco utility pumps. Even Rule electric bilge pumps, they can come apart. I also like taking things apart to see why they broke.

I bought a Rule 3700 from Ebay seller, which when arrived was smashed by shipper. Seller sent another one which was OK. I repaired the first one and so got 2 for 1 price. If you drop these from a height, they are so heavy they crack when they hit the ground.

That Jabsco utility pump uses a bronze lip seal bearing, very expensive. From the local seal sellers, that seal coated in rubber is $4. And I put on an O-ring instead of the metal spring that supports the lip since it would rust in sea water. Been great now for 5 years.

I like the idea of replacing the vent through hull with just an open fitting. I thought the screen part was necessary but I guess it isn't. I installed a "penis" on my chain locker drain to keep the chain rust off the hull. I can make a through hull out of PVC and give it a try. Those cheap plated through-hulls don't last long at all.

Talkin' with other D.I.Yers about the problem of buyin' whole Jabsco rebuild kit when you only need one part. Someone mentioned a vendor called, Go2Marine that sells individual Jabsco parts. Worth a try.

By us between many pump out stations and pump out boats no need for a discharge pump, one less thing to go wrong...

Installed the rebuilt macerator pump today and replaced the holdin' tank vent with a 5/8" S.S. thru hull fittin'. Accordin' to my well-kept maintenance records, I am gettin' three years between rebuilds, and that is with a 12 month boatin' season. Got a four day raft-up this Memorial Day week-end and do not anticipate any head problems.

When I had a Jabsco pump I was replacing it every year. Switch to this brand and had much better performance.

Measuring the lifespan of a pump in years is pretty useless. Counting the run time and the amount of time it's run dry would be more meaningful.

I can't imagine why anybody would continue to use that style of macerator pump.