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05-17-2018, 03:33 PM
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#1
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Senior Member
City: Cape Coral
Vessel Name: Tonic
Vessel Model: 2007 Mainship Pilot Sedan 34
Join Date: Mar 2018
Posts: 152
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Raw water pump - Sanity check
I’m troubleshooting the raw water system on a Next Gen 5.5kw and need a sanity check. For the pump pictured, which would be the inlet, and which is the outlet?
Thanks,
Brett
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05-17-2018, 03:37 PM
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#2
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Guru
City: Jacksonville
Vessel Name: SONAS
Vessel Model: Grand Alaskan 53
Join Date: May 2014
Posts: 7,235
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Which hose goes to the through hull?
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05-17-2018, 03:43 PM
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#3
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Senior Member
City: Cape Coral
Vessel Name: Tonic
Vessel Model: 2007 Mainship Pilot Sedan 34
Join Date: Mar 2018
Posts: 152
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That would be too easy.
The pump can be turned 180 degrees, putting the intake hose on either fitting. To clarify my question, based on the rotation of the impeller, should the inlet be connected to the top, or bottom?
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05-17-2018, 03:44 PM
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#4
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Guru
City: Brookline, NH
Vessel Name: Shalloway
Vessel Model: Defever 44, twin Perkins
Join Date: Sep 2013
Posts: 2,260
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Top is inlet
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05-17-2018, 03:49 PM
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#5
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Guru
City: Quebec
Vessel Name: Bleuvet
Vessel Model: Custom Built
Join Date: Jan 2016
Posts: 4,375
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Quote:
Originally Posted by Tonic1
I’m troubleshooting the raw water system on a Next Gen 5.5kw and need a sanity check. For the pump pictured, which would be the inlet, and which is the outlet?
Thanks,
Brett
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Out at the bottom of the picture.
L
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05-17-2018, 03:51 PM
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#6
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Guru
City: Philadelphia
Vessel Name: Dreamers Holiday
Vessel Model: Mainship 390
Join Date: Jun 2010
Posts: 572
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Top. looking at this end of the pump it is turning clockwise. The pumping chambers open at the top near the hose and close at the bottom near the bottom hose so the pump is pulling the water in the top and pushing it out the bottom. That is one way to tell. Also when you have 2 different size hoses as you do here, the largest hose will always be the inlet.
John
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05-17-2018, 04:05 PM
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#7
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Technical Guru
City: Wilmington, NC
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 6,194
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Need to rotate engine and see which way impeller rotates. If CW, top is inlet.
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05-17-2018, 04:15 PM
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#8
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Senior Member
City: Cape Coral
Vessel Name: Tonic
Vessel Model: 2007 Mainship Pilot Sedan 34
Join Date: Mar 2018
Posts: 152
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Thanks all, I thought top as well, and that was how it was connected. Since I’m getting no flow, and strainer is clear, time to pull hoses and check fittings in the supply side.
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05-17-2018, 04:17 PM
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#9
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Senior Member
City: Seattle
Vessel Name: Mabuhay
Vessel Model: Grand Alaskan
Join Date: Jan 2018
Posts: 399
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Pump is designed to have water travel the long way around...and in this case the top would be the inlet.
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05-17-2018, 04:44 PM
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#10
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Guru
City: Fort Myers, FL... Summers in the Great Lakes
Vessel Name: Slow Hand
Vessel Model: Cherubini Independence 45
Join Date: Dec 2010
Posts: 12,835
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While you have the cover off, spin the engine to see if the impeller turns. The raw water pump on my Onan snapped the tap on the shaft where it mates to the engine.
Ted
__________________
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05-17-2018, 05:30 PM
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#11
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Senior Member
City: Cape Coral
Vessel Name: Tonic
Vessel Model: 2007 Mainship Pilot Sedan 34
Join Date: Mar 2018
Posts: 152
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Good idea, O C Diver. I’ll check that as well.
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05-17-2018, 05:55 PM
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#12
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Technical Guru
City: Wilmington, NC
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 6,194
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Worn pump won't want to prime. With pump all together, try to blow air through the pump, if air whistles through things are worn. Also bought a couple impellers that were like 0.020" shorter than normal and those would not prime.
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05-17-2018, 06:17 PM
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#13
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Guru
City: Jacksonville
Vessel Name: SONAS
Vessel Model: Grand Alaskan 53
Join Date: May 2014
Posts: 7,235
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If you look at how the impeller fins are against the constricted side of the housing you see that the impeller rotates clockwise looking from this side.
The water is picked up at the top hose and, because of the constriction bending the fins closed, is forced out at the bottom.
How long has it been sitting - could the heat exchanger be clogged?
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05-17-2018, 06:30 PM
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#14
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Senior Member
City: Cape Coral
Vessel Name: Tonic
Vessel Model: 2007 Mainship Pilot Sedan 34
Join Date: Mar 2018
Posts: 152
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Generator only started periodically to load check for past year. No extended run time in that period, but noticed minimal flow through exhaust the last few times. Checked strainer, all clear. Replaced impeller, no improvement. Cleared a bunch of impeller blades from the outlet hose. These must have been there a long time, because I replaced the impeller over a year ago and the one I removed was in good shape.
Planning to remove and check all hoses from strainer through heat exchanger and go from there. Just wanted to double check that the pump was oriented properly before I got too deep into it.
Thunderstorm chased me home today, and traveling all next week, so I’ll hit it after Memorial Day. Thanks again to all.
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05-17-2018, 06:31 PM
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#15
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Guru
City: Philadelphia
Vessel Name: Dreamers Holiday
Vessel Model: Mainship 390
Join Date: Jun 2010
Posts: 572
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While checking hoses, You might just as well change the inlet hose. Pumps work by creating a partial vacuum at the inlet then atmospheric pressure (14.7 psi at sea level) pushes the fluid into the pump. Its possible that you could have cut inside the hose that closes off the line when put under a vacuum. I've seen people pull off the hose and look through it and say its ok the reinstall and have it close as soon as the pump turns.
John
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05-17-2018, 06:33 PM
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#16
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Guru
City: Jacksonville
Vessel Name: SONAS
Vessel Model: Grand Alaskan 53
Join Date: May 2014
Posts: 7,235
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Ok, my $1 is on a badly clogged exchanger. A boat sitting that long in Coral Gables warm water has got lots of little creatures up in there!
Waiting for what you find!
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05-17-2018, 07:28 PM
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#17
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Guru
City: Queensland
Vessel Model: Milkraft 60 converted timber prawn trawler
Join Date: Jul 2016
Posts: 5,482
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So many answers and methods but the first was the most obvious and simple.
Quote:
Originally Posted by menzies
Which hose goes to the through hull?
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05-17-2018, 09:35 PM
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#18
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Guru
City: Jacksonville
Vessel Name: SONAS
Vessel Model: Grand Alaskan 53
Join Date: May 2014
Posts: 7,235
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Quote:
Originally Posted by Simi 60
So many answers and methods but the first was the most obvious and simple.
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Simi, because he was getting no water throughput he was questioning whether or not the pump was put on correctly. Or whether it was 180 degrees off!
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05-18-2018, 05:20 AM
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#19
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Guru
City: Aventura FL
Vessel Name: Kinja
Vessel Model: American Tug 34 #116 2008
Join Date: Oct 2017
Posts: 10,595
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Quote:
Originally Posted by menzies
If you look at how the impeller fins are against the constricted side of the housing you see that the impeller rotates clockwise looking from this side.
The water is picked up at the top hose and, because of the constriction bending the fins closed, is forced out at the bottom.
How long has it been sitting - could the heat exchanger be clogged?
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Send a diver down to check the hull inlet or pull the hose on the hull valve to see if it flows free.
__________________
Two days out the hospital after a week in the hospital because of a significant heart attack.
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05-18-2018, 11:46 AM
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#20
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Guru
City: Warwick, RI
Vessel Name: Susan Helena
Vessel Model: Albin40
Join Date: Oct 2014
Posts: 523
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Quote:
Originally Posted by johnma
While checking hoses, You might just as well change the inlet hose. Pumps work by creating a partial vacuum at the inlet then atmospheric pressure (14.7 psi at sea level) pushes the fluid into the pump. Its possible that you could have cut inside the hose that closes off the line when put under a vacuum. I've seen people pull off the hose and look through it and say its ok the reinstall and have it close as soon as the pump turns.
John
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My genny intake hose delaminated on the inside and closed off flow. Great idea to change intake hose regardless. Boy did that one drive me crazy for a while.
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