Maserator pump

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AMCarter3
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Re: Maserator pump

Postby AMCarter3 » Mon Sep 04, 2017 7:07 pm

Hi Dick, hope you are enjoying Labor Day. We're out in the San Juan islanda having a great time, but also experiencing a macerator issue. See next entry.
Last edited by AMCarter3 on Mon Sep 04, 2017 7:32 pm, edited 1 time in total.
Mac Carter
2006 34' PDQ PowerCat "All Heart"; MV 98
Bellingham WA

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Re: Maserator pump

Postby AMCarter3 » Mon Sep 04, 2017 7:21 pm

I have a macerator issue right now. Our Jabsco 18590-2092 unit appears to be failing... when turned ON, it sounds like it is bogged down handling a heavy load. It quickly slows down to a crawl... even though the hose from the tank to the motor is empty. So quickly that to avoid overloading the circuit, I turned it off.

I took the Y-valve out and verified there is nothing clogging the inlet hose into the macerator. The short inlet hose to the macerator was completely clear.

I removed the overboard discharge hose from the macerator- it was clean and dry... and I could see there was nothing inside the macerator gear... I could see the gear turn when powered ON.

Note: while examining the hoses, I noticed that 2 of the 4 brass bolts that attach the gear section to the motor were missing.

At this point, I think the symptoms point to a failing macerator motor, OR MAYBE IT HAS SIMPLY LOST ITS PRIME? What do you guys recommend?
Mac Carter
2006 34' PDQ PowerCat "All Heart"; MV 98
Bellingham WA

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Re: Maserator pump

Postby thinwater » Mon Sep 04, 2017 8:41 pm

When you say "gear" I assume you mean the flexible impeller? I also assume you mean the "hose from the tank to the pump."

There are only four things that can make it bog down:
1. Blockage. Does it spin up properly with no hoses attached (Lube with K-Y or glycerin to prevent wear and over heating when running dry. Not grease--that can damage the impeller)?
2. Impeller is swollen. The impeller is neoprene, and excessive use of vegetable oil in the head can make it swell and get too big for the space. Replace the impeller. This is most likely. And stop using oil and any other cleaners. Certain bowl cleaners can also do this. Lysol will do it.
3. Bad bearing. I doubt it, but new pump.
4. Bad motor or bad connection (high resistance). I doubt it, but check the connections for tightness and corrosion, both at the pump and the switch.

Loss of prime will not make it bog down unless it runs long enough to get hot (a minute or so). Not impossible that damage was done by running dry. The cure is to replace the impeller and remove the blockage (assuming there is a valve on the tank, get some fittings and blow it back with a garden hose).
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Re: Maserator pump

Postby AMCarter3 » Tue Sep 05, 2017 12:22 am

First, thanks for the quick reply.

By "gear" I did not mean the impeller. I mean the silver colored gear that can be seen when looking down into the vertical outlet port at the top of the macerator... where the discharge hose attaches. Thus gear has "teeth" and spins when the motor is turned ON.

The motor does NOT spin up with a "normal" sound with no hoses attached. It starts with a lower frequency sound "like" the motor is already stressed or loaded up (if that makes sense). The sound frequency then quickly declines like it is slowing down... like it is struggling with a clog... yet there is zero evidence of a clog in the hose leading into of out of the macerator.

I cannot see the impeller. We have not disassembled the unit. We do not use any oil or any cleaners of any kind in the system. We do flush ½ capful of Noflex Digestor in the toilet each day.

I would appreciate clarification on where and how to lubricate the unit. That might be worth testing.

I will also pursue the idea that the impeller is the problem. Is it possible for a blockage to exist only in the impeller? Again, there is zero evidence that a blockage exists anywhere else.

And, given that 2 of the 4 bolts are missing from the face of the the impeller section, I am inclined to simply replace the unit.
Mac Carter
2006 34' PDQ PowerCat "All Heart"; MV 98
Bellingham WA

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Re: Maserator pump

Postby deising » Tue Sep 05, 2017 7:41 am

Mac,

On our previous boat, I had the bearings seize and needed to replace the entire unit. It used salt water to flush.

On our PDQ, one of the previous owners wisely replaced the impeller macerator with a diaphragm pump that is reputed to be "bulletproof." Many in the PDQ community have reported they were now worry-free with the diaphragm pump. I wish I could tell you with certainty what brand we have, but it escapes me.

I am pretty sure there are other threads on this same topic in the forum.
Duane Ising
m/v Diva Di
Punta Gorda, FL
2006 PDQ MV 34 - hull 91, 75HP, 3-blade

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Re: Maserator pump

Postby AMCarter3 » Tue Sep 05, 2017 9:34 am

Hi Duane,

Ours is a fresh water system, but the macerator is acting like it may be seizing up OR has a damaged impeller. (This is my conjecture; I Do not actually know how these Jabsco units are constructed yet).

I've seen the positive comments about the diaphragm style unit; also heard about them from local friends... I understand they requir a bit more space and some plumbing modifications.

My challenge is that we are out on the water now till Thursday; then the boat goes out on charter Friday eve for a week. So, I would like to resolve this by this Friday. My plan now is to contact West Marine in Friday Harbor, WA (San Juan Usland) today to see if they have my Jabsco model in stock. If not, I will order it today so I have it Thursday.

Any other ideas or diagnostic suggestions from anyone are appreciated.
Mac Carter
2006 34' PDQ PowerCat "All Heart"; MV 98
Bellingham WA

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Re: Maserator pump

Postby deising » Tue Sep 05, 2017 9:56 am

Hi, Mac.

I know what you mean; when time is short, you can't be making a project out of it. Best thing (IMHO) is to replace the whole unit at this point, as you are doing.
Duane Ising
m/v Diva Di
Punta Gorda, FL
2006 PDQ MV 34 - hull 91, 75HP, 3-blade

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Re: Maserator pump

Postby duetto » Tue Sep 05, 2017 7:24 pm

hi,

having gone thru the rebuild/replacement cycle many times, we switched to diaphragm in our 2003. we switched to a sealand. teamwork (2005) has also switched but to a jabsco.

fix/swap in a jabsco to do your charter.

my advice is to take measurements and lay out where replacement would go including any extra plumbing hose, and next time you have free time do the swap. trust me, with a boat in heavy duty use you'll be doing this a lot.
john & diane cummings
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Re: Maserator pump

Postby thinwater » Wed Sep 06, 2017 12:47 am

If you mean the 2-bladed chopper plate, that macerates the waste but has little to do with pumping force.

Image

In your situation, I would get a new pump and possibly rebuild the existing one, when I had time.
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"Keeping a Cruising Boat for Peanuts"
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Re: Maserator pump

Postby AMCarter3 » Wed Sep 06, 2017 10:24 am

Excellent help on this. Really appreciate the advice. I did get a new Jabsco and installed it yesterday I Friday Harbor. It tested out perfectly, so the pressure is off for now. I'll disassemble the old one to find what happened (I could see some small threads wrapped inside the choppers.)

I like the idea of switching to a diaphragm model. If you have one on your PDQ 34, please send a photo of where and how it is mounted. I assume it's mounted in the starboard bow locker where the Jabsco is currently mounted.
Mac Carter
2006 34' PDQ PowerCat "All Heart"; MV 98
Bellingham WA

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Re: Maserator pump

Postby duetto » Wed Sep 06, 2017 10:31 am

the key to a pump surviving is to NEVER let it run dry. once the pump runs dry for more than 30 or so secs the impeller will overheat and cease to work. so the question is how do you know when you're going to run dry. as the pump gets to the end of emptying the tank the running sound will change and when empty it really changes sound. so the key is to listen to the pump when emptying the tank and shut off immediately when the sound changes. diaphragm pumps can run dry w/o suffering damage.
john & diane cummings

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Re: Maserator pump

Postby thinwater » Wed Sep 06, 2017 11:17 am

^^ Good advice!
Writing full time since 2014.

http://sail-delmarva.blogspot.com/2017/ ... store.html
"Keeping a Cruising Boat for Peanuts"
"Singlehanded Sailing for the Coastal Sailor"
"Faster Cruising for the Coastal Sailor"

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Re: Maserator pump

Postby AMCarter3 » Thu Sep 07, 2017 10:28 am

Thanks again for all the input. This forum is a terrific example of a string community of folks sharing and working together in a common interest.
Mac Carter
2006 34' PDQ PowerCat "All Heart"; MV 98
Bellingham WA


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