replacement of Sherwood Raw Water pump

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Capt. Sam's picture
Capt. Sam
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replacement of Sherwood Raw Water pump

I've searched that couldn't find a word on this. I need to replace my Sherwood raw water pump on my '94 Westerbeke M35. First, my engine overheated and had to be shut down in a channel 6 miles from home slip. (God bless Towboat US and if you don't have that insurance get it now).
Of course the problem was a deteriorated empeller that I replaced the next day and everything ran well with no over heat, but now there's a steady drip from what looks like a hairline crack in the pump housing. Tightened all the mounting bolts and still leaks. Has anyone out there replaced the whole thing and is it straight forward? Where can I buy a new pump? And lastly, is there anything else I should check after my engine overheated? I shut it down within in less than a minute of the overheat warning going off and it seems to run fine.
Thanks for any help.
Sam
:(

Capt. Sam Murphy
1994 Catalina 36, Hull 1327
Shoal draft, two cabin model.
Panama City, Florida

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Steve Frost
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Sam,

If you shut down that quick lets hope for the best on collateral damage.

As for the pump swap there were articles in the technical section of Mainsheet two issues back as I recall. I do not recall as good as I used to.

Steve

Cepheus dream
C36 MK I # 825
MK I Tech Editor No Mas

FlyMeAway
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Posts: 241

I would check the gaskets and seals on the heat exchanger. I'm going through this now -- at the end of last season, had a minor overheat (forgot to open the raw-water seacock). Everything else was fine (though the impeller needed to be replaced), the engine ran for less than a minute once the overheat alarm came on, and I managed to shut it off and coast into a berth (still in harbor).

However, my first real full careful inspection of the engine this year, it's clear that zinc oxide was forced out around the head exchanger (I've been meaning to post pictures and a thread about this, and will soon). While I'm not getting any obvious leakage, it's pretty clear that the steam build-up in the heat exchanger forced water out around the ends (at least, that's what I think happened -- more discussion when I actually make my post). The rubber seal, when I took the thing apart, is clearly a bit deformed. Worth a replacement, and not expensive.

Just my thoughts.

David
s/v Portmanteau
Hull #2133 -- 2003 MKII
Seattle, WA

BudStreet
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Sam, here is the link to the Jibsheet article that may be the one Steve is referring to. It is actually about converting from Sherwood to Oberdorfer but I believe there is some info in there that may be useful to you because getting a Sherwood can be difficult as they are no longer made. Try Depco pump or Marine Diesel Direct. You might want to just go with the Oberdorfer conversion as that pump is way cheaper and is still in production. I'm assuming you have an M35A based on your boat year.

[URL]http://www.c36ia.com/node/1837[/URL]

If that link doesn't work here's a link to the PDF of the Jibsheet issue:
[URL]http://www.c36ia.com/files/JS-Sep10.pdf[/URL]

From recollection when I took mine off about 3 years ago there are just two bolts holding it onto the block. Reinstalling it is as simple, you just have to make sure the drive pieces line up correctly and that it seats all the way in.

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stu jackson c34
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Sam, many skippers have replaced their Sherwoods with Oberdorfers, and many think it (the O) is a better pump (better materials). There is a writeup of this swap out on your C36 site. We also have it on our Tech wiki with permission, so if you can't find it here, please let me know.

Stu Jackson, C34IA Secretary, C34 #224, 1986, SR/FK, M25 engine, Rocna 10 (22#)

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Gsmith
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Sam

I had the Sherwood on my M35A showing signs of weeping and needing a rebuild. Decided to replace with the Oberdorfer N202M-16 following the instructions in the article referenced above. The modification of the mounting flange to avoid a boss on front of engine is easy, a slight notch is required. I used a dremel but it could be done with a file if necessary, job took about 30 minutes total. A quick Google search shows pricing currently runs about $260 from industrial pump suppliers as well as Catalina Direct. Good Luck

Gary Smith
93 MK I, Hull #1231
Std rig; wing keel
M35A Oberdorfer conversion
 

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Capt. Sam
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Again, my helpful friends, I'm amazed at the help I get here. Thanks so very much, And David, I didn't want to admit it but a week before I had this problem, I too took off from my slip to the fuel dock after forgetting to open the raw water sea cock. (Had a new girl aboard, so its her fault);) and the overheat warning didn't go off until I got fuel and just got back into my slip. I shut down immediately but I think the pump running dry damaged the impeller enough to cause the eventual failure on Saturday. So I got what I deserved.
I'm studying the info provided. I also have that corrosion showing on the edges of the heat exchanger. I think I'll remove and open it up as part of this process. Thanks again for all the very relevant help.:)
Sam

Capt. Sam Murphy
1994 Catalina 36, Hull 1327
Shoal draft, two cabin model.
Panama City, Florida

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Capt. Sam
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Just a follow up. I decided to replace my failing (leaking) Sherwood pump with the above recommended Oberdorfer. I ordered mine from one of the florida dealers that Oberdorfer told me about. It was less expensive than Catalina Direct and arrived in two days. There was one change not mentioned on the above referenced link, that I had to back out two inserts in the existing mounting holes in my M35AC Universal/Westerbeke that weren't previously used by the Sherwood. Takes an allen wrench and about 2 minutes, and buy two new mounting screws as the Oberdorfer uses four flange mounting screws as opposed to the Sherwood only two with lugs. (seems weird to me but the Oberdorfer method seems much better).
The other modifications described in the link were easy with my drimel tool and dressed up with a flat file. The result is very satisfactory, with engine running at a cool 150 deg. F after a half hour at idle. Relatively easy job and best of all the new Oberdorfer was $250 compared to the new Sherwood at $500. Thanks C36IA guys!:D

Capt. Sam Murphy
1994 Catalina 36, Hull 1327
Shoal draft, two cabin model.
Panama City, Florida

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deising
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Sorry about your problem, Sam. It is very true that if you know or suspect that your raw water impeller has run dry for more than a few seconds, you really better replace it ASAP. Running dry heats it up so much that it permanently damages the rubber.

"Good judgment comes from experience, and experience comes from bad judgment."

Duane Ising - Past Commodore (2011-2012)
s/v Diva Di
1999 Catalina 36 Hull #1777
Std rig; wing keel, M35B, Delta (45#)
Punta Gorda, FL
http://www.sailblogs.com/member/diva-di/

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Capt. Sam
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Words of true wisdom Duane. And here's a photo of my ruined impeller to help make the point.
Nice feature of the Oberdorfer pump is that it has an easy to remove plate that allows quick inspection of the impeller and replacement
And by the way, what preventive maintenance should I be doing to my fresh water cooling pump? Same thing? replace impeller?
Thanks
Sam

Capt. Sam Murphy
1994 Catalina 36, Hull 1327
Shoal draft, two cabin model.
Panama City, Florida

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BudStreet
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Posts: 1127

Those pumps are "maintenance free". Until they quit, then you replace them. They usually give you warning, leaks start showing up here and there. But typically they last a long long time. Other nice thing is they are a stock Kubota part so you can get them cheaper from a Kubota tractor dealer, if there's none in your area there's lots online, Messick's being one.

One other thing with that Oberdorfer pump I believe you can get a Speedseal for it. Makes impeller changes even faster.

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deising
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I am going out on a limb here, since I don't know for sure, but I think the coolant pumps are centrifugal in design and do not have any soft rubber impellers in contact with the housing. Just turning the pump with the v-belt off shows that is has no friction other than the fluid (coolant).

I hope someone can confirm, but I don't think you have to worry about that one.

Duane Ising - Past Commodore (2011-2012)
s/v Diva Di
1999 Catalina 36 Hull #1777
Std rig; wing keel, M35B, Delta (45#)
Punta Gorda, FL
http://www.sailblogs.com/member/diva-di/

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TomSoko
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Sam,
I'm glad the Oberdorfer swap worked well for you. I agree with Bud and Duane. The fresh water (recirculating) pump's design is the same as the water pump in your car. Hard vanes that work by centrifugal force and not contact/displacement. Preventative maintenance involves not over-tightening the alternator belt, and possibly completely loosening the belt during an off season.

Tom Sokoloski
C36/375IA Past Commodore
Noank, CT

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Capt. Sam
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Thanks guys, that's excellent news, that there's a component I don't have to worry about, well maybe just a little.
Thanks
Sam

Capt. Sam Murphy
1994 Catalina 36, Hull 1327
Shoal draft, two cabin model.
Panama City, Florida

gorgonshead
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New question on this topic: Do you think the modification shown above could be done with a hand hack saw rather than the saws-all shown in the article?

Peter L

Peter Lundquist
s/v Rafael
1998 Catalina 36
Hull #1669
Salem, MA

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Capt. Sam
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No, If you're talking about the slight removal of metal on the bronze flange on the Oberdorfer pump to make it fit around the steel stud that sticks out of the Universal M35A, I think a hack saw is not the right tool. I'd use a drimel if you have one. (If not, I'd buy one because they are invaluable) or a rat-tail and/or flat file. The amount of metal to be removed is very little and should be rounded to clear the stud. Try to keep the shavings out of the pump to avoid abrading the new impeller.
Sam

Capt. Sam Murphy
1994 Catalina 36, Hull 1327
Shoal draft, two cabin model.
Panama City, Florida

gorgonshead
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I'm talking about the larger amount of metal to be removed for the M35B - I don't think the dremel tool is up to that.

Peter Lundquist
s/v Rafael
1998 Catalina 36
Hull #1669
Salem, MA

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deising
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Peter,

I just received my Oberdorfer pump from Cartalina Direct and plan to make the modification for my M35B within the next few weeks. The housing is bronze, which sounds like a hand-held hacksaw should work, but there are some pretty tough, hard bronze alloys out there.

I plan to try the hand hacksaw and then get my sawz-all involved if needed.

Duane Ising - Past Commodore (2011-2012)
s/v Diva Di
1999 Catalina 36 Hull #1777
Std rig; wing keel, M35B, Delta (45#)
Punta Gorda, FL
http://www.sailblogs.com/member/diva-di/

prh77
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One more thought on fresh water pump maintenance; changing the antifreeze. It has anti-corrosion additives and lubricants for the pump. Do it every 2 to 3 years. Also as noted, keep the belt tension relaxed, it is hard on the bearings. You do not want belt slippage, but be gentle.

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Kelly Supply Company price: $208.00, shipping estimate was $18.07.

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deising
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Reporting on the conversion to the Oberdorfer pump for my M35B engine:

I used the JibSheet article right here on our website as a guide. Overall, I am pleased with the result, but I did not quite get the new hole located in the proper place at first and without access to a milling machine, I had to use a Dremel tool and grinding bit to make it fit.

I also had to buy shorter machine bolts and over-sized washers. I did make all the cuts with a hacksaw and had no problems.

I don't mind changing the impeller from time to time, but I hope the pump seals and bearings give me longer life than the Sherwood.

The still working, not-leaking Sherwood pump and all the required fasteners are still onboard as a spare, just in case.

One of our officers has accepted my two old Sherwood pump housings and will attempt a rebuild. Perhaps he will report on this progress when the time comes.

Duane Ising - Past Commodore (2011-2012)
s/v Diva Di
1999 Catalina 36 Hull #1777
Std rig; wing keel, M35B, Delta (45#)
Punta Gorda, FL
http://www.sailblogs.com/member/diva-di/

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[QUOTE=deising;17790]... but I hope the pump seals and bearings give me longer life than the Sherwood.[/QUOTE]

Duane, actually it's not the seals and bearings that are too much different, it's the construction of the bodies of the pumps between the Sherwood and Oberdorfer. When we bought our boat in 1998, it appeared to have the original Oberdorfer pump, 888 engine hours. I bought a new one in 1999 because of the leaking and because I didn't yet know how to rebuild the pump. In late 2012 or earlier this year, I rebuilt it, again because of leaking, but we had 2600 engine hours!!! I can attest that the Oberdorfer will outlast any Sherwood pump, given the discussions here and on our C34 site.

I think you made the right move.

Stu Jackson, C34IA Secretary, C34 #224, 1986, SR/FK, M25 engine, Rocna 10 (22#)

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baysailor2000
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I have all the images and drawings of how the Oberdorfer pump can be modified to fit M35B. I did it myself and it takes a drill press and hack saw and Dremal tool. I also replaced the 4 Phillips screws with Allen head . If you PM me I will send you the CD with everything you need to know.

Haro Bayandorian, 1999 C36 MKII, Sail La Vie #1787, M35B,
Coyote Point, San Mateo, CA.

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deising
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Thanks, Haro, but I did the job yesterday. It all came out well.

Also, thanks to Stu for confirming it was worth the effort.

Duane Ising - Past Commodore (2011-2012)
s/v Diva Di
1999 Catalina 36 Hull #1777
Std rig; wing keel, M35B, Delta (45#)
Punta Gorda, FL
http://www.sailblogs.com/member/diva-di/

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