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Old 08-11-2020, 09:29 AM   #1
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Onan MDJE7.5 Raw water pump

The salt water pump on my trusty old 7.5kw onan genset is slowly giving up the ghost, these pumps are notoriously expensive to repair or replace. The unit is a slot driven direct bolt on unit and very rare. Others have written about replacing the unit with a March (or other) electric pump. Looking for any new or additional info anybody has regarding this..

Thanks
HOLLYWOOD
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Old 08-11-2020, 09:38 AM   #2
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That is what I am planning on doing. I bought a small March pump, but have not yet installed it. My WP is still good though, so no hurry. I may have a spare of two for you. I will look if your interested.



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Old 08-11-2020, 04:03 PM   #3
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Quote:
Originally Posted by Redhook98 View Post
That is what I am planning on doing. I bought a small March pump, but have not yet installed it. My WP is still good though, so no hurry. I may have a spare of two for you. I will look if your interested.



-Rich

Thanks for the offer, I am currently considering buying a decent copy of the entire genset we currently have as a spare parts donor, the electric pump option seems to check a few of the boxes to lessen maintenance and keep the noisemaker in the boat for the future.
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Old 08-11-2020, 04:21 PM   #4
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Call Depco and discuss your options. They have all the parts, or the whole pump, or can rebuild it for you, and discuss alternatives. The pump authorities.

http://online.anyflip.com/ucrc/jfuq/...dex.html#p=134
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Old 08-11-2020, 05:04 PM   #5
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Can you get too little flow rate and overheat? I am supposing with a position displacement engine it would be hard to get too much. You could screw up and not have the pump shut down along with the generator and flood it. These issues bugged me; so I chose to leave my MDJE fully stock except for the miserable little POS heat exchanger which I junked in favor of a much bigger copper/nickel unit which I mounted off the genny.
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Old 08-13-2020, 03:03 PM   #6
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I use a March pump in place of the belt-driven pump on my 7.5 MDJE. It's worked great for several years now. It's wired directly to the generator output, so no way it can run without the motor running. It cools fine, the flow seems at least as good as, if not better than, the old pump.
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Old 08-13-2020, 04:22 PM   #7
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I replaced our failed pump with a March pump on a MDJA 3.5KW and wired it to the output ,no chance of flooding the engine. The pump works better than the original with no problems.
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Old 08-13-2020, 11:31 PM   #8
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I switched to a electric and ran for 4 years. It was wonderful. I am trying to pm you the instructions which were given to me by another member edelweiss
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Old 08-14-2020, 12:06 AM   #9
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I switched to a electric and ran for 4 years. It was wonderful. I am trying to pm you the instructions which were given to me by another member edelweiss

I got the info, Thanks again

HOLLYWOOD
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