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Newbie Question--Impeller for MX25

Kenneth K

1985 32-3, Puget Sound
Blogs Author
Time to order a new raw-water pump impeller for my MX25 in preparation for spring. I might also amass a few spare parts while I'm at it (O-rings, cover plate screws, retainer ring, etc). I have an Oberdorfer N202M-15 pump. It has an O-ring faceplate seal rather than the old paper gasket. I found the following online:

Factory Impleller = Oberdorfer part #6593 = Universal part #295628. Prices range $35-65 for just the impeller, but occasionally a vendor will include the O-ring, too.

I was wondering if anyone has tried Globe Run-Dry Impellers. Defender shows the Globe #815 as a replacement for the Ober. #6593. They claim it will run dry for 15 min and last 2-3 times longer than the factory part. I always have my doubts about cheaper parts ($21) that claim to be better. By appearance, the hub/drive portion of the Globe appears thinner/less-substantial than the original, and looks like it might be plastic rather than metal.

Also, does anyone know if Jabsco offers a replacement for the Ober. #6593? Their parts seem to have a reputation for quality.

I found these previous EYO links, but no specifics Globe or Jabsco replacement parts:

http://www.ericsonyachts.org/infoexchange/showthread.php?6955-Globe-Impeller
http://www.ericsonyachts.org/infoexchange/showthread.php?12819-Impeller-Change-Universal-Diesel-5416

Also, the Defender Link: http://www.defender.com/product3.jsp?path=-1|51|2234245|2234249&id=591852

Thanks,

Ken
 

Rocinante33

Contributing Partner
I have used the Globe impeller the last time or two that I have changed it and it has given me good service.

Where did you get your O ring cover plate? I would like one of those.
 

Kenneth K

1985 32-3, Puget Sound
Blogs Author
Keith,

Guess I should have been more precise. The cover plate is flat. The O-ring sits partially recessed in the pump housing face. It sounds like Oberdorfer switched to this configuration in 2004.

Ken
 

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Geoff W.

Makes Up For It With Enthusiasm
Blogs Author
Ken, I'm looking at this same thing as spring comes upon us. What impeller(s) have you ended up going with, and sourced from where?
 

Kenneth K

1985 32-3, Puget Sound
Blogs Author
Geoff,

Like Keith said, I had good luck the past season with the Globe 815 and Defender usually has the best price. The Globe is easier to install as the blades are softer.

I had a bad time last year with a factory impeller that wouldn't fit on the pump shaft. I had to file down the flat part on the hub to get it to fit. That's when I switched to the Globe.

On a recent post (something about running your engine on-the hard) another user commented that Globe 815s have a history of the hub (which is plastic, compared to brass on the factory impeller) wearing out and letting the shaft turn inside the impeller. I haven't heard of anyone else who has experienced this, though.

If you buy the factory type (I carry both), I stopped buying from Westerbeke.com or the Catalina website--too expensive. Check out pump vendors (pumpsandpartsonline.com, etc). They usually offer a kit with impeller, snap ring, o-ring , carbon seals, etc, all for the price that Westerbeke charges for just the impeller.
 

bgary

Advanced Beginner
Blogs Author
I haven't tried the Globe.

What I have found is there are Oberdorfer "kits" which contain more than just the impeller.

I found Oberdorfer part#11691 is the good (probably overkill) set of spares for my Oberdorfer N202M-16 1KD pump. It contains impeller, lip-seals, retaining ring, o-ring, paper-gasket and carbon bearing.

IIRC, I got the kit at Harbor Marine in Everett; Fisheries carries it (about $75 for the full kit)

https://www.fisheriessupply.com/oberdorfer-pump-n202m-flange-mount-bronze-impeller-pump-spares-11691

Not the least expensive option, but... peace of mind that the parts are OEM.

Bruce
 

debonAir

Member III
I've tried the regular (hard rubber?) and Globe (nitrile? polyurethane/) and found the Globe was a bunch stiffer and thought it might wear the cover plate quicker than the plain one. The cover plate wear *seems* to be the thing that kills these pumps which are otherwise just big hunks of expensive bronze. The o-ring is a significant upgrade over the old paper gasket which breaks into the half that sicks to the pump and the half that sticks to the cover, and, maybe, helps with longevity?

On the more contentious side, I have read about (but not witnessed) the run-dry type impellors actually cracking and disintegrating vs. just having a blade break off. and the bits being able to migrate into the exchanger.

I carry a spare of each type now. The run-dry for when/if I need to diagnose a pump issue, the plain for when it gets resolved.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Oferdorfer adventures

I regularly installed new impellers in the stock Oferdorfer pump on our former M25XP for over 20 years. I found that some grease on the paper gasket would allow it to part in one piece, usually.
As for the "life" of the pump, I finally did have to replace the whole pump due to gradual wear of the innards of the pump casting. (Our Columbia River water has very sharp fine rock particles in suspension, owing to the main flow from mountain sources. This acts as an abrasive, over time, and the pump slowly loses thru-put and pressure.

Several years ago I sourced a new pump at the suggestion of our mechanic, and that improved model had the O-ring incorporated in the cover plate.
The slowing of flow is not easy to document, but the improvement in water out the transom exhaust was quite noticeable after the upgrade.
 
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