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Author Topic: JMP Raw Water Pump?  (Read 2402 times)

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kyleolmstead

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JMP Raw Water Pump?
« on: May 09, 2023, 07:09:46 PM »

Hello! Has anyone had success using JMP Marine JPR-WB7108 raw water pump on their M-35B engine? Thoughts? Seems that it can replace the Sherwood G908.
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Breakin Away

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Re: JMP Raw Water Pump?
« Reply #1 on: July 11, 2023, 10:30:44 AM »

Did you end up purchasing this? I'm looking for recommendations, since it is all bronze and priced much more reasonably than Sherwood's new bronze pump.

Is the pump cavity the same size as G908, or is it smaller like the Oberdorfer? Will it use the same replacement impellers as the Sherwood version?
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2001 MkII Breakin' Away, #1535, TR/WK, M35BC, Mantus 35# (at Rock Hall Landing Marina)

pbyrne

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Re: JMP Raw Water Pump?
« Reply #2 on: July 11, 2023, 10:56:14 AM »

Did you end up purchasing this? I'm looking for recommendations, since it is all bronze and priced much more reasonably than Sherwood's new bronze pump.

Is the pump cavity the same size as G908, or is it smaller like the Oberdorfer? Will it use the same replacement impellers as the Sherwood version?

And can you replace the impeller from the FRONT.  I don't like the current Sherwood design.  I get it but the boat is on the hard 6 months of the year, and removing/installing the impeller twice a year is a PITA....
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2000 Catalina 34 MK II #1534

KWKloeber

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Re: JMP Raw Water Pump?
« Reply #3 on: July 11, 2023, 11:17:59 AM »

Did you end up purchasing this? I'm looking for recommendations, since it is all bronze and priced much more reasonably than Sherwood's new bronze pump.

Is the pump cavity the same size as G908, or is it smaller like the Oberdorfer? Will it use the same replacement impellers as the Sherwood version?

And can you replace the impeller from the FRONT.  I don't like the current Sherwood design.  I get it but the boat is on the hard 6 months of the year, and removing/installing the impeller twice a year is a PITA....

No. Itís essentially the same as the stupid Sherwood design.
JMP claims the parts are not universal and you need its kit (minor or major kit.)

If one doesnít like the design JUST SWITCH to an Oberdorfer. Itís the simple answer.

You canít buy the $$$herwood any longer.  Only the ridiculou$$$$$ Westerbeke pump.
« Last Edit: July 11, 2023, 02:03:01 PM by KWKloeber »
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Twenty years from now you'll be more disappointed by the things you didn't do, than by the ones you did.
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pbyrne

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Re: JMP Raw Water Pump?
« Reply #4 on: July 11, 2023, 11:39:10 AM »

Did you end up purchasing this? I'm looking for recommendations, since it is all bronze and priced much more reasonably than Sherwood's new bronze pump.

Is the pump cavity the same size as G908, or is it smaller like the Oberdorfer? Will it use the same replacement impellers as the Sherwood version?

And can you replace the impeller from the FRONT.  I don't like the current Sherwood design.  I get it but the boat is on the hard 6 months of the year, and removing/installing the impeller twice a year is a PITA....

No. Same as the stupid Sherwood design.
They claim the parts are not universal and you need its kit (minor or major.)

If one doesnít like the design JUST SWITCH to an Oberdorfer. Itís the simple answer.

You canít buy the $$$herwood any longer.  Only the ridiculou$$$$$ pump.

Ok.  The engine has less than 900 hours on it, so it'll be years before the pump goes on it's own... but man do I despise that impeller design....
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KWKloeber

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Re: JMP Raw Water Pump?
« Reply #5 on: July 11, 2023, 02:08:10 PM »

Do not base the longevity of a Sherwood on engine hours especially if you are in salt!!!

Make SURE THAT THE REINFORCING RING IS INSTALLED. And DO NOT let ANY water drip out the weep hole go uncorrected..
The camshaft that you save could be your own.
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Twenty years from now you'll be more disappointed by the things you didn't do, than by the ones you did.
So throw off the bowlines.  Sail away from the safe harbor.  Catch the tradewinds in your sails.
Explore.  Dream.  Discover.   -Mark Twain

Ron Hill

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Re: JMP Raw Water Pump?
« Reply #6 on: July 11, 2023, 02:44:49 PM »

Guys : The biggest problem that I found with the Sherwood is the they used a bronze "C" clip to keep the spring compressed. I wrote up a Mainsheet tech note article on how to rebuild a Sherwood and listed the size and source of getting a replacement Stainless "C" clip.

Ken is correct - if you see water dripping out of a Sherwood repair that leak!! 

A few thoughts
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Breakin Away

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Re: JMP Raw Water Pump?
« Reply #7 on: July 11, 2023, 08:09:30 PM »

I did not intend to ignite more rage over the Sherwood vs. Oberdorfer debate.

Someday I may opt to buy the Oberdorfer pump, but I still wince when I see how much smaller its pumping cavity is. Two years ago I posted some calculations to back up my concerns over its lower capacity for motors over 30 hp. But I realize that many people use it on their 35 hp M35B motors and are happy with it. I am not ready to try it now, but maybe someday.

The simple fact is that a third company has now come out with an all-bronze knockoff of the Sherwood at a fraction of the cost (around $400). That's worth discussing. Competition between different pump companies is good for the consumer.

I am not bothered by "backwards" direction of the Sherwood pump cavity. I'm able to get my skinny fingers behind it to remove the 3 screws, and to pull the cavity off the impeller without having to disconnect the hoses. However I am bothered by the potential for rust causing failure of the G908 bearings. So the opportunity to buy an all-bronze Sherwood knockoff for $400 is worth my consideration. But only if I can confirm that JMP is a reputable pump manufacturer, and that it matches the pumping volume of the Sherwood. That's the reason for my question about cross-compatibility of the impellers - that would answer my question about its capacity. I know that JMP recommends using their impeller - every company recommends using their own replacement parts. But if JMP is selling their replacement impeller for use in the Sherwood G908, that suggests that the pump cavity is the same size.

So rather than beating the Sherwood vs. Oberdorfer horse to death, I'd love to hear comments from someone who has actually seen the JMP version.

EDIT: I just answered one of my questions. JMP sells their own replacement impeller (#7172-01) as a replacement for the Sherwood impeller (Westerbeke #200175). https://www.jmpusamarine.com/products/7172-01k-jmp-marine-flexible-impeller-kit/

Therefore, the pump cavities are the same size. Based on this, I might purchase the JMP and keep my Sherwood as a spare. I'll think it over some more, and look to see if there are happy customers out there somewhere.
« Last Edit: July 11, 2023, 08:18:18 PM by Breakin Away »
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Breakin Away

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Re: JMP Raw Water Pump?
« Reply #8 on: July 21, 2023, 05:59:01 AM »

As I previously mentioned to Kyle on Facebook, I have purchased the JMP all-bronze pump and will be installing it in the near future. At some point I'll provide an update on how it's working.

I plan to inspect the current Sherwood G908 to ensure there's no rust, and if everything looks good I will keep it as an emergency spare. But I will no longer have to worry about iron rust causing the bearings to seize and break my cam shaft.

I will have to transfer my elbow fittings over from the Sherwood pump to the JMP. What is the preferred thread treatment for this? Is Teflon tape OK, or is there some liquid pipe dope that is preferred? I've always used Teflon tape for everything, but want to be sure to follow best practices for this critical application.
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2001 MkII Breakin' Away, #1535, TR/WK, M35BC, Mantus 35# (at Rock Hall Landing Marina)

KWKloeber

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Re: JMP Raw Water Pump?
« Reply #9 on: July 21, 2023, 05:00:39 PM »

Interesting if you can see what, if any, the differences are. 

The only information I have been able to get is that 'the Korean JMP engineers have redesigned the internal parts and improved them'  -- nothing of substance as to why they are better -- which makes me cautious.  And yet the impellers are interchangeable. 
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Twenty years from now you'll be more disappointed by the things you didn't do, than by the ones you did.
So throw off the bowlines.  Sail away from the safe harbor.  Catch the tradewinds in your sails.
Explore.  Dream.  Discover.   -Mark Twain

Matthieu G

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Re: JMP Raw Water Pump?
« Reply #10 on: August 28, 2023, 02:06:16 PM »

As I previously mentioned to Kyle on Facebook, I have purchased the JMP all-bronze pump and will be installing it in the near future. At some point I'll provide an update on how it's working.

I plan to inspect the current Sherwood G908 to ensure there's no rust, and if everything looks good I will keep it as an emergency spare. But I will no longer have to worry about iron rust causing the bearings to seize and break my cam shaft.

I will have to transfer my elbow fittings over from the Sherwood pump to the JMP. What is the preferred thread treatment for this? Is Teflon tape OK, or is there some liquid pipe dope that is preferred? I've always used Teflon tape for everything, but want to be sure to follow best practices for this critical application.


Hey Breakin Away,

Did you install your new JMP pump finally ?
Iím about to rebuild my Sherwood and may consider a swap.

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Matthieu Girard
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KeelsonGraham

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Re: JMP Raw Water Pump?
« Reply #11 on: September 13, 2023, 06:19:16 AM »

Iíd also love to hear about your experiences with the JMP pump.
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