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Universal M-25XPB Sherwood Raw Water Pump Questions

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Nov 18, 2010
2,399
Catalina 310 Hingham, MA
Hello All,

I have a Catalina 310 with a Universal M-25XPB. The raw water pump is a Sherwood. If anyone has ever changed the impellar on this pump, they know what I am going to ask. To access the impeller, the bolts are difficult and you can not use a ratchet or ratchet wrench. You can only use a open-end wrench and you don't get that much turn per attachment due to limited space.

My biggest fear with this water pump is if I ever had to change the impeller in an emergency situation. It takes me about 15-30 minutes to change it due to this difficulty.

It is time to either rebuild or replace my pump. And since the one I have is highly rusted, I plan to replace. I may eventually rebuild for a back up.

I have looked at some threads about changing to an Oberdorfer raw water pump that has more traditional access to the impeller. But while many have discussed it, I have not seen any updates from anyone who actually made the change.

So here are my questions:

  1. Has anyone actually made the switch and how did it go?
  2. Am I being overly paranoid since I have a raw water strainer?
  3. Should I just suck it up and continue with the Sherwood?

Thanks All.
 
Feb 26, 2004
21,141
Catalina 34 224 Maple Bay, BC, Canada
The Sherwood pump design is totally crazy!

Here's an article about the rebuild of our Oberdorfer pump. The change to an Oberdorfer is simple, it's a straight swap out replacement. You can get the best buy on an Oberdorfer pump from www.depcopump.com in Florida, a lot less expensive than a Sherwood (who won't do any price discounts).

http://c34.org/bbs/index.php/topic,6766.0.html

There are two you can choose from: the N 202M-15, which has an O ring on the faceplate and a reversible faceplate, or the standard 202M-15 which uses a paper gasket for the faceplate with only one "inside" face on the faceplate. We have the 202M-15 in the article.

I strongly urge you to make the change.
 

gpd955

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Feb 22, 2006
1,164
Catalina 310 Cape May, NJ
Stu Jackson said:
I strongly urge you to make the change.
Where was that advice last week when I bought and installed my new Sherwood??!!!! :)

JK--- when I changed out the impeller the first time with the Sherwood I decided to take the exact tools needed for the change and put them in a box with the gasket and impeller, just to save time since it is a real pain to do that. An option if you continue with the Sherwood.

If I'd have known about the Oberdorfer, I would have switched!! When I had my 30, I replaced the pump on my atomic 4 with one that had a quick release plate that came in handy when I had to replace an impeller underway, especially with the limited access I had. Would be nice to have it on the 310,

Anyway I wondered what engineering genius decided to put such important pieces in a place where they are invisible and inaccessible on a part that is probably the most accessible on this engine! Kind of defeats the purpose!
 
Feb 26, 2004
21,141
Catalina 34 224 Maple Bay, BC, Canada
Where was that advice last week when I bought and installed my new Sherwood??!!!! :)
Gee, Jack, ya didn't ask, didja now? :cussing:

And I thought you read our C34 Message Board, too. :eek:
 
Jan 6, 2010
1,520
Catalina 30 Mark II John's Pass Florida
Jack,

Stu is the one of the best voices of reason on this site. I have the Universal 3M20A, which came with the worst pump of all....Sherwood.

If you look at the exploded views, the sherwood has 21 parts to it and is designed to FAIL. The Oberdorfer on the other hand is a well designed pump and has lasting power with far fewer parts.

Two years after I got my engine, the pump failed. Westerbeke just took over ownership and the replacement cost tripled. I bought another "Shitwood" pump that lasted a year before leaking. I put in a changout Ober, and it's the best pump.

If you go this rout, get 1 or 2 impellers as spares pal. Hope this helps.......

CR
 
Nov 6, 2006
8,711
Hunter 34 Mandeville Louisiana
Not the blue spare impellers.. get the real black ones.
 

gpd955

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Feb 22, 2006
1,164
Catalina 310 Cape May, NJ
Jack,

Stu is the one of the best voices of reason on this site.
Don't I know it! If it weren't for him and Maine I probably would get nothing done.

The only reason I stayed with the Sherwood was that I needed the boat useable because we had to move from the winter slip on Wednesday last week and I didn't have the opportunity to do any research or take the risk of needing modification. If she were on the hard, I would have probably asked about it and spent more time looking.



You know I use them, Stu!! The 34 forums are bookmarked on my iPhone and I use them like the engine manual!! I found their "M25XP Equivalents" very helpful yesterday when I was stocking up on filters! The tech wiki on there is probably one of the most useful sites on the internet!
 
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Bob S

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Sep 27, 2007
1,559
Beneteau 393 New Bedford, MA
JK,

I made the change and it was quite easy. I'm not sure I would worry about needing to change your impeller in a hurry. I had to do it while floating in Buzzards Bay. I forgot to open my through hull and didn't realize it until i noticed we were overheating. It shouldn't take more than 10 minutes once you've done it once. I did the Oberdorfer change because the pump started weeping oil and when I pulled it apart it fell apart so bad it wasn't worth rebuilding. Did you already change the impeller? Sounds like you've already taken it apart. I have an extra impeller if you need it. I'm not far from you. You can also buy the Sherwood or Oberdorfer in Dorchester at Associated Diesel. You can pick it up and save the shipping charge.

http://www.adiesel.com/store/OB-N202M-15.html

There prices are very good. I buy my fuel and oil filters (Baldwin) from them. Good price for a good filter.
 

gpd955

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Feb 22, 2006
1,164
Catalina 310 Cape May, NJ
While we are on this topic.....

My Sherwood is attached using 2 clamps that bolted to the engine. The Oberdorfer pumps you guys are looking at haave 4 holes that I assume are placed on 4 posts/bolts that are on the engine. Am I correct in this assumption? If so, is there another mod to the engine that needs to me made or is there a different pump? My engine is the M25XPB but it is also listed as the XPC--- for Catalina......and I think we resolved on this forum that the only difference between the XPB and XPC is wiring.

The pic is the old pump so it doesn't look that bad now!
 

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Nov 18, 2010
2,399
Catalina 310 Hingham, MA
Thanks everyone. Bob S, I have the same issue as yu had. I pulled it to rebuild and didn't like the quality of what is left. Thanks for the Dorchester hook up, that will be handy.

JK
 
Sep 29, 2008
1,799
Catalina 310 #185 Quantico
I considered it but

while the Oberdorfer is easier to change, it does provide less performance as far as water flow. Considering that I decided to stay with the Sherwood, at least until it breaks. :eek:
 

Bob S

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Sep 27, 2007
1,559
Beneteau 393 New Bedford, MA
Jack,

The Oberdorfer has the same bolt circle and mounts directly. You don't need the clamps the Sherwood used. Mine was the same and it confused me too. Actually, if you look at the pic in the link, the pump has 5 holes which probably makes it universal to many engines.
 
Nov 18, 2010
2,399
Catalina 310 Hingham, MA
It Doesn't Just Bolt On

:cussing::cussing::cussing::cussing::cussing::cussing::cussing::cussing:

OK, so the N202M-15 has two major flaws for use on the M-25XPB, or any Universal as far as I can tell:
  1. It does NOT just bolt on, none of the bolt patterns line up. You can see what needs to be ground off of the pump housing in black on the photo below.
  2. The fittings are 3/8" and the fittings that are on the Sherwood are 1/2". This means you have to have some additional fittings in line to bush up from 3/8 to 1/2".

If I had not already spent the day messing around with pump, I would return it and get the N202M-16. From the manufactures website it appears the same basic shape and has 1/2" fittings. Otherwise, just be prepared to have to do some modifications to the pump to make it fit.
 

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Jan 6, 2010
1,520
Catalina 30 Mark II John's Pass Florida
Guys,

Unless Westerbeke changed their manuals, or stopped having optional pumps, There should be an Ober option. The parts list that came with my engine had both Ober & sherwood interchangeable pump exploded views, & listed by part nos.

They should also have matching bolt patterns. I wouldn't think you would need to modify anything.

To verify this call R.B. Grove in Miami @ 305-477-0277 or a local Westerbeke dealer. Make certain you have the correct pump. Ask for the Ober model number, & then hunt for a better price (not Westerbeke) to save some money.

CR
 

Tom J

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Sep 30, 2008
1,630
Catalina 310 Quincy, MA
Thanks for the post, JK. I already ordered the same pump from Associated Diesel, but I'll be looking to return it and get the one that fits better. I'll probably bring the Sherwood to Associated Diesel and compare it to what they have.
 
Feb 26, 2004
21,141
Catalina 34 224 Maple Bay, BC, Canada
:cussing::cussing::cussing::cussing::cussing::cussing::cussing::cussing:

OK, so the N202M-15 has two major flaws for use on the M-25XPB, or any Universal as far as I can tell:
  1. It does NOT just bolt on, none of the bolt patterns line up. You can see what needs to be ground off of the pump housing in black on the photo below.
  2. The fittings are 3/8" and the fittings that are on the Sherwood are 1/2". This means you have to have some additional fittings in line to bush up from 3/8 to 1/2".

If I had not already spent the day messing around with pump, I would return it and get the N202M-16. From the manufactures website it appears the same basic shape and has 1/2" fittings. Otherwise, just be prepared to have to do some modifications to the pump to make it fit.
I hear you.

Try this, and please read Reply #8 and click on that link, too.

http://c34.org/bbs/index.php/topic,6769.0.html

I forgot if you said where you bought your pump, but you could also call Depco, www.depcopump.com.

Also: Rebuilding an Oberdorfer pump:

http://c34.org/bbs/index.php/topic,6766.0.html
 
Feb 26, 2004
21,141
Catalina 34 224 Maple Bay, BC, Canada
while the Oberdorfer is easier to change, it does provide less performance as far as water flow. Considering that I decided to stay with the Sherwood, at least until it breaks. :eek:
Ray, I've heard that so many times, but I still ask myself the question: "If my Oberdorfer keeps my engine "happy and cool" what the heck difference does it make?"

And yes the Sherwood does pump more water and has more vanes. But the Sherwood pump body has parts that are NOT bronze. The O is better pump for a M25 series engine, as well as for M35s: http://www.c34.org/wiki/index.php?title=Replacing_a_Sherwood_Water_Pump_with_an_Oberdorfer
 

jerry

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Jun 9, 2004
60
Catalina 320 500 Stockton, Mo.
Anybody try this one: MMI 502

Mine started leaking too. I have a 1991 Catalina 28 18 hp Universal M3-20 and am looking at the MMI 502 flange pump at Moyer Marine. It looks like an excellent repalcement. Any thoughts?
 
Jan 22, 2008
597
Oday 35 and Mariner 2+2 Alexandria, VA
I have the Ober. No issues at all. Keeps the engine at a good operating temp, impeller is easy to change (I still have the old paper gasketed cover plate which will get changed out later this season.)
 
Jan 6, 2010
1,520
Catalina 30 Mark II John's Pass Florida
Guy,

I've read alot here about flow rate questions/advice between the Ober & Sherwood pumps.

I don't recall what the Sherwood flow rate was on my 3M20A, but the Ober was rated @ 9.3 gph.

Water in Florida in summer can get into the 90 degree range, so engine cooling is very important here.

I had some high temp. readings with my out of the box engine when I first got it.
I remember re-checking everything over & over to no avail, and finally really started to look at the heat exchanger.

What I found, was that the heat exchanger was underated for the engine. I believe the orig. was a 2 pass type. I contacted Sendure Inc. who makes these. I downloaded their generic shop drawing and revised the in/out connections to agree with my hose & needed zinc connections.

I had them make me a 4 pass HE with a 3 1/2" dia. outer shell. After installing it, my water temp. never goes higher than the OEM specs. It sticks @ 165 degrees no matter what time of year I'm runnung in.

Some thoughts that if you're concerned with flow rates, or maybe running alittle hot, check to see what the OEM supplied.

CR
 
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