Sherwood Raw water pump

sail4dale · November 22, 2009, 03:26:49 PM

There does not seem to be a malfunction of my Sherwood raw water pump
but I have heard that when you see any
water showing in the weep holes you should do a repair job.
Conversely, I have also heard that it is not unusual to see some weeping
in those holes and maintenance is not needed.

I would love some input from this great panel of experts.

Stu Jackson · November 22, 2009, 05:07:54 PM

It's been explained simply: if you see weeping, it's time for service.

Can't get much simpler than that. I'd like to meet those who say differently, and not just because I believe that, it's the way the pumps are designed and built.

Weep holes are what's called "telltales" like sail telltales that tell you which way the wind is blowing.

Based on the May 2002 writeup in Mainsheet by Ron Hill, recently noted in Rick Allen's pump woe story, rebuilding a pump is not rocket science. The only issues are whether you do it yourself or pay to have someone do it or buy a completely new pump.

Ron's article also explained where the seals are located and just why you shouldn't see water coming through the weep holes UNLESS it's time for service. I looked it up and read it earlier today.

The Critical Upgrade topic was NOT kidding.

And if you don't believe me, call DEPCO and ask them.

Ron Hill · November 22, 2009, 06:00:09 PM

Dale : The difference between the Oberdoffer and the Sherwood is like night & day!!
If your Sherwood has a drip I'm not too sure that I'd immediately take it off and rebuild it. I'd watch it and look at that weep hole while it's running. That damn Sherwood has a cast iron body(holding the water & oil seals) that is bolted to the engine, even though the water pump housing itself is bronze.

You just need to watch that weep hole. That water seal on a Sherwood 906/908 is comprised of two ceramic seals that are compressed against each other - one turning and one stationary. The smallest piece of junk could cause a drip or two (with rust from the iron body!) and cause alarm. Then it may go away. Just keep an eye on it (while running) before you panic.
Also, it's difficult to see the bottom weep hole with the steps in place, as I can just barely see that port side pump from the head alternator door - which I believe the MKIIs don't have!! A few thoughts

Jack Hutteball · November 22, 2009, 10:31:04 PM

Ron and Dale,

I am now on my third Sherwood with 550 hours on the engine. I monitor my engine faithfully, so I noticed when they started to drip. None of them ever quit or got better, just continued to get worse. I was not happy with salt water dripping down the front of the engine and running across the oil pan. Per Ron's comments, better to fix the pump rather than replace the oil pan.

Jack

sail4dale · November 23, 2009, 11:34:01 AM

interesting input form all three of you experts..

Jack, did you repair any of the Sherwoods or buy new ones? Were there any re-manufactured ones available? Any "deals" available on new ones?

Also, I am intrigued by Ron and Stu not totally agreeing on what action to take when it drips slightly.
I guess I will have to address the situation in one way or another before long. I have read the input on many phases of Cat34 life from these gentlemen for a few years. Thanks for the past hints.

Stu Jackson · November 23, 2009, 01:04:04 PM

Quote from: sail4dale on November 23, 2009, 11:34:01 AMAlso, I am intrigued by Ron and Stu not totally agreeing on what action to take when it drips slightly.

Please note that my experience is with an Oberdorfer pump, as were my recommendations, and Ron's Mainsheet article. I do not have a Sherwood pump and never would because of the backwards screws on the face plates. Given what I've learned about Sherwoods recently, if I had one and I was $$ enough to replace the pump, I'd buy an Oberdorfer because of ease of replacing the impeller, getting them on discount, no cast iron in the construction, and the "better" weep holes (the picture's on the Critical Upgrades topic).

Ron Hill · November 23, 2009, 02:34:49 PM

Guys : The two differant pumps have two differant ways to seal the raw water side of the pump.

On the Oberdoffer the lip seal is riding on the shaft. Inside the lip seal there is a spring that keeps the seal
compressed onto the shaft. So when you get a drip it's only going to get worse because the rubber lip may be worn or it's making a grove on the shaft and it will NEVER get any better - just worse.

On the Sherwood all I'm recommending is watch it and see. I've already replaced one Sherwood at 117 hrs and am not impressed with the design. Another case of an engineer in closed room without windows designing something and he did not have to work on in the real world.

I've always professed that when any piece of military equipment is first used in combat, that it be manned by contractor personnel - we'd have the best designed equipment in the world!! A thought

Jack Hutteball · November 24, 2009, 04:47:02 PM

Dale,

I replaced both of mine with new as I read on this site that a rebuild of a Sherwood usually requires a new shaft and they are unavailable (makes one wonder why when one can but a new pump at top $). I do not have any tools that will push bearings in and out. Both times they started leaking was just before I planned to head out for 3 weeks, so it was quicker to simply order and replace (30 min job). I have the two leaking ones sitting on my workbench and plan to ask a local shop about rebuilding them. This might be a good time with the economy such as it is.

Jack

Ron Hill · November 26, 2009, 12:39:04 PM

Jack : My pump was still under warrenty, but I did purchase the replacement seals for the water and oil. The oil looks like a press in seal, while the water seal appears to be a spring loaded cermic seal held in with a "C" clip.
When I have to "rebuild that Sherwood", I'll write an article. Until that time I'll let the warrenty "do the work" and let someone else fix it!!

Jack Hutteball · November 27, 2009, 03:39:50 PM

Ron,

Interesting, my last Sherwood went out at almost exactly the same amount of hours as yours. Certainly says something about engineering? Did not think about warranty on mine, but think it was probably past the time as I only put about 50 hours a year on the engine.

Jack

mainesail · November 27, 2009, 07:21:15 PM

While not a Sherwood or Oberdorfer this article my help those of you wishing to undertake your own DIY pump re-build. In writing this I tried very hard to use products most boaters would have around the house..

http://www.pbase.com/mainecruising/raw_water_pump

Rick Allen · November 27, 2009, 08:38:54 PM

As usual Mainesail, your pictures and website are excellent. Thanks for your post.

Rick

Fou Du Large · November 29, 2009, 07:29:02 AM

My motor is a M-25 (old model)
Is it possible to replace the Sherwood by a Oberfolder?
Th
ank you.

Stu Jackson · November 29, 2009, 07:32:56 AM

Quote from: Fou Du Large on November 29, 2009, 07:29:02 AMMy motor is a M-25 (old model)Is it possible to replace the Sherwood by a Oberfolder?

Oberdorfer - yes it is, no modifications necessary, just buy the Oberdorfer and install it. We have the M25 engine, too.

Craig Illman · November 29, 2009, 12:49:14 PM

Stu - I don't want this to sound like a contradiction, but when I added the Oberdorfer N202M-15 to my M25XPA, I needed to find some 3/8-18 NPT to 5/8" hose elbow fittings. The Sherwood pump has 1/2" NPT output. I don't recall where exactly I found them, but the local Universal distributor wasn't much help.

http://www.oberdorfer-pumps.com/Spec_sheets/202M%20Series%204%20page.pdf

You also need a couple metric cap screws. Ah, order a gasket too, it doesn't come with the pump.

Craig