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

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.

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.

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.

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

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."

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.

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.

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.

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

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,

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.

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.

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

If several people wanted to order simultaneously additional savings might be had...

Mark

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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.

[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.

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.

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

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