JMP full bronze replacement raw water pump

[waughoo]

I have been working through raw water flow optimization ever since puchasing my boat.  The sherwood G908 that came with the boat was leaking rather significantly and due to the challenges many had reported, I swapped to the oberdorfer.  I have the m35 which with 4 cylinders seems to be a bit shy on flow so I am leaning towards going back to the sherwood.  That said, I have never been fond of the non bronze portions of the g908.  In searching I found that JMP makes an all bronze replacement of their own (albeit slightly modified).  Has anyone fitted this on their boat or does anyome know of someone who has?  My main concerns revolve around locating an impellor when needed.   

https://www.jmpusamarine.com/products/jpr-wb7108-jmp-marine-westerbeke-replacement-engine-cooling-seawater-pump/

[Ron Hill]

Alex : It sure looks good, but didn't see how it attached to the engine?!

A thought

[waughoo]

There are some brackets with through bolts that hold it in place.  It is exactly the same as what the orginal sherwood used to hold it to the block.

[KWKloeber]

Alex

The old iron body Sherwood G908 is NLA, and the replacement Sw bronze body pump is also discontinued.
Westerbeke has its own "new" round base pump ($$$$)

See
https://groups.io/g/Catalina30/message/114295

Someone on here reportedly installed the JMP —- but shoutouts about it have gone unreturned.

[KeelsonGraham]

The JMP pump is really good. I installed one at the beginning of the season. Everything mates up nicely and the casting quality looks good. Nice also to have an all-bronze unit.

[KWKloeber]

The JMP pump is really good. I installed one at the beginning of the season. Everything mates up nicely and the casting quality looks good. Nice also to have an all-bronze unit.

Keelson

Do you notice anything different about that pump, guts-wise?

JMP claimes that the innards are upgraded from Sherwood's but they haven't yet explained what,  exactly, is upgraded whitchaway.  Impeller?  Bearing?  Shaft?  Seals? 
It's all rather mushy what the distributor is claiming. 
Surely it cannot be just empty talk from a marine manufacturer/supplier!

Thx
Ken

[waughoo]

Keelson,

Glad to hear of a first hand user.  Is the impellor specific to JMP or will the stock sherwood impellor slot in?  One of my concerns is getting an impellor.

[KWKloeber]

Alex
JMP told me that the impeller specific 

There should not a problem getting impellers from the USA distributor and one of the several dealers.

[waughoo]

Ken,

Curious... at least that answers the question about SOME-thing thats different.  Thanks for the info Ken.

Alex

[Breakin Away]

JMP markets their impellers as replacements for the Sherwood impellers, so it stands to reason that if JMP were to someday disappear that you could pop in a genuine Sherwood impeller into the JMP pump.

Another option is to send your leaky Sherwood out to be rebuilt. Depco rebuilt mine several years ago for about $100. They only had to rebuild the water-side seal - a full rebuild would be more.

Interesting that you think your Ob pump has too little flow. I've always been concerned about the design being on the edge for warm water locations. Yours is the first time I've heard about a potential flow deficiency in a cold water location. FWIW, Depco and Hansen Marine both advised me not to use the Ob for engines above 30 HP. My M35B is 35 HP, so I won't install the Ob. Others feel differently, but many of them have the smaller engines.

[Jon W]

FWIW - A few months ago I was curious about the Ob N202M-15 and -16 GPM at various M25XP engine RPM's. I talked to an engineer at Ob about determining ballpark numbers. We came up with a very rough scheme. I'm hesitant to post it because I know the data is 30,000 foot level values only good as a reference. Determining the exact values as you know is a very involved process. I'll post it if interested.

[KWKloeber]

JMP markets their impellers as replacements for the Sherwood impellers.

Wondering....  Where did you find that info the JMP markets its impeller for the G903/G908? 
JMP told me the opposite, and the published pump info states that "internal parts" are not compatible.

Depco and Hansen Marine both advised me not to use the Ob for engines above 30 HP.

True, but the backstory explains what the average owner doesn't know.

A condition of Hansen's distributorship agreement with Westerbeke FORBIDS it from selling or recommending an Oberdorfer pump for a Universal engine.  It also may not advertise any part for less than Westerneke retail. 

Therefore, it's not shocking that Hansen finds a reason to recommend a Westerbeke part over an Ob part.

Technically, being an authorized Westerbeke dealer, Depco is also prohibited from selling a non-Westerbeke part to "knowingly" be used on a Westerbeke engine (I'm not claiming they don't get away doing it.)

I had discussed the flow question with the (former) Depco marine pump manager, who admitted that he had no data or known complaints or failures, or science-based justification that supported the claim not to use it on a 4-cylinder.  None whatsoever - it is just what (hearsay) they "understood."

Randy in LA (the Gulf is pretty warm) has no issue whatsoever with the Ob pump on his 35B.

The mere fact that the Sw pumps more, is sufficient fodder for Westerbeke to instill fear in owners that its part is better and the Ob is deficient.

Facts do not play into it, fear does — even if both pump sufficient water.

JTSO, based on fact not fear.

[Ron Hill]

Ken & Guys : The best upgrade to the Sherwood pump would be to change out the bronze "C" clip to a stainless "C" clip - especially if you are in salt water!!   
Years ago Jabsco finally figured that out for the "C" clip on the bottom of their head hand pump!! Daaa!!

A few thoughts

[waughoo]

Jon... I'd be interested to see your details.

Breakin',

I have an expectation that I should be able to run flat out without the temp rising.  At cruising speed, it stays at 165 or so.  I have been working through things... I was way over propped, changed for a campbell sailor to allow engine to reach full spec rpm at max throttle. Cleaned injectors to make sure they werent running lean.  Used banacle buster on the heat exchanger.  Found the water jacket for the fresh water circuit was rusty... rust acts as an insulator.  Flushed fresh water circuit and then filled with evaporust.  Have been running that now for the summer.  The next step is to drain the evaporust and remove the heat exchanger and have it boiled out at a radiator shop. 

I have a few other ideas to change the 90 degree fittings at the OB pumps for 45s to reduce head pressure.  The last step will be to try the JMP pump.

I really like to fiddle.  The boat behaves in a predictable fashion so it presently isnt a limiting factor.  I feel the cooling system should have enough overhead to cool the engine even at max load.  Figuring it out is an intereating puzzle.

[Jon W]

My apologies, I realized I had mixed up reference cells on the original PDF. I've attached a revised version.

Hi Alex, Keep in mind the data is extrapolated, and is for the M25XP. The Ob guy said it was a reasonable method to get the "on engine" pump GPM, but cautioned more analysis would need to be done to be truly accurate. You will need to determine gear ratio's for an M35 to get pump GPM's. PDF attached.