Sherwood waterpump on M-35B

[c34member]

Can anyone explain to me the design concepts involved in deciding to mount the raw water pump on the Universal M-35B Engine so that the bolt heads face away from the mechanic and are behind the pump housing and must be removed backwards?  Further complicated by the alternator belt blocking access from top and sides.  What kind of sadists design thses things?  Granted, there are no threads to potentially strip in the engine casing the way they did it, but is it worth it?

[bjmansfield]

Charlie:
when the Sherwood started leaking on our M35, I replaced it with the Oberdorfer 215-M which is not a mirror-image bass-ackwards design like the Sherwood and the Oberdorfer costs around $115 as I remember.  The Sherwood was a  LOT more.  As I recall, just the rebuild kit for the Sherwood was $85 or so.

I once had to replace the impellor in the Sherwood while sitting at an exposed anchorage in the ICW and used every four-letter word I knew during the process.

I highly recommend converting to the Oberdorfer when you have to replace the pump.

[This message was edited by Jack Mansfield # 1169 on May 02, 2001 at 07:24 PM.]

[Stu Jackson]

I recently replaced my water pump.  My inventory records: Pumps: Raw Water, 11/30/99, Oberdorfer 202M-15   $285.12   Sea Power - hoses, clamps, tools, seals & gaskets.  So the cost for the pump itself was pretty much around $160.

The reason I replaced the pump was that the guts of the old pump were worn enough to cause a steady leak which ended up rusting out the forward starboard portion of the engine, and didn't do the motor mount any good either.  It would have cost almost as much as the new pump to have the shop pop new bearing seals into the old body, so I opted for an all new pump, shaft, impleller (the whoe shebang) and kept the old stuff around as a backup.  One of these days I'll work on replacing the seals per Nigel Calder's suggestions.  Didn't want to try it with only one pump.

A few years ago there was a long Mail List discussion about the merits of Sherwood vs Oberdorfer pumps.  I may still have that if you're interested, email me directly and I'll dig it up.  (mraquaq@aol.com).

It took me a lot of time to get the old pump out because the studs were rusted in.  It sure helped that they were accessible, which doesn't seem to be the case with the Sherwoods.

We have an M25, not an XP.

One other note, previously noted on the old Mail List:  the blow up drawing of the pump (in the engine manual) is different with regard to the end of the shaft inside the pump.  The one shown makes it darn near impossible to replace the shaft inside the pump housing without having to take off the whole pump body to get the shaft aligned inside.  That makes replacing the impleller a real treat, because you can't move the shaft out.  The newer impeller shafts have a different end shape on the shaft which makes pulling the shaft (with the old impleller still mounted) out of the pump body, replacing the impleller and sliding the shaft back in a very easy task.  Don't ask me how it works inside with a different shaft end, but it sure makes it easy.

[Norris Johnson]

I just replaced my raw water pump because the shaft to it was broken inside of the gear cover. I had to remove the engine head and the gear cover. The shaft to the pump is a continuation of the cam shaft, so it had to be replaced. Westerbeke was very good, in that, they sent me all of the parts free with a sleeve that slips over the shaft that comes out of the block. This tells me they knew they had a problem. I would highly recommend that anyone who has one of these engines contact Westerbeke to get one of these sleeves. There are only two size 10mm cap screws that hold the pump on. The shaft broke due to a seal failure between the pump and the bearing housing. This let salt water freeze up the bearing and break the shaft. You don't want to have to do this job, even with free parts!

[Ed Shankle]

I had to replace the raw water pump 2 years ago. Had the Oberdorfer, and Hanson Marine replaced it with the new Sherwood. I too cursed the backwards design with the screws. I have found, however, that a closed end wrench, the one that has about a 10-15 degree tilt, works great to access the nuts.
I don't know if the pump design is any different on the 35. I have an 25XP. According to Hanson, the new design Sherwood is supposed to be much better then either the old design Sherwood and the Oberdorfer.

[jrupinsk]

Norris,

Is there any way of identifying a problem without taking everything apart or finding out the hard way?

[Norris Johnson]

Yes, you can remove the pump and bearing housing by disconnecting the two 10mm bolts that connect the pump and bearing housing to the gear cover. Disconnect the suction and discharge hoses. Now you can remove the pump and bearing housing and turn the shaft with your fingers or with a pair of pliers. The bearing housing can be visually inspected without removing anything. It has some drain holes in it that will indicate if there is water getting into it. If you are in salt water, the drain holes or slots will be rusty. If this is the case, I would recommend you getting a new bearing housing with a good seal. If there is water getting into the bearing housing, the seal has failed.

[This message was edited by Norris Johnson on October 09, 2001 at 05:32 PM.]