This is actually for Brian on the halyard hang up thread but as the topic was wandering I’m posting it as a separate thread.
Many of us have water pumps that are hard to access. Impeller removal / replacement can be made easier by replacing the tiny bolts with studs and using nuts or better yet knurled nuts to secure the cover. This makes it easy to locate the plate in position with one hand and then come back with the nuts. If you have a paper gasket it can be independently placed before the plate, all with one hand, one piece at a time. For studs I just use longer bolts with the heads cut off and locktite them in place.
With knurled nuts the impeller can be changed quickly in an emergency and they can be snugged up later when you are out of danger. I find that hand tight will be leak proof but I like to give them a little tweak with pliers.
Thanks, Paul! I actually had that thought, briefly, about the third time that the gasket fell off, but promptly forgot about it once I achieved success. Since it works for you I will put a note in the box with my spare impeller, hopefully to do it next year.
The pump is apparently bronze. Since screws are more easily replaced and I’d like the studs to last, what material would you recommend for them?
Stainless steel has been working for me for a long time. It’s generally okay with bronze anyway but the Locktite isolates the metals too. This isn’t the first pump I’ve done this to. Even just replacing a couple of the bolts will let you get the pieces in with one hand. That’s pretty easy to do in place. I did all of these because I was replacing the pump.
Inspired by this thread I’ve upgraded my water pump, and oh boy what a difference. So so much easier to put on and off the plate, not loosing nuts in the bilge etc.
In case it’s helpful here are the McMaster Carr parts for my pump on a W33. All brass parts.
Robin: Not being a metallurgist, is it OK to use brass on bronze on a boat?? I was always told to stay away from brass.
Joe Valinoti
S/V iL Gatto NS30U #221
Sea Harbour YC
Oriental, NC USA
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Brass is generally fine on a boat above the waterline but this is a place where salt water is present so stainless is a better idea. I just bought long enough bolts and cut the heads off to make studs. Locktite will isolate them from the pump body.
I’m not sure, Robin. Above my pay grade. I would Google bronze/brass interaction on boats unless someone on in the group knows.
Joe Valinoti
S/V iL Gatto NS30U #221
Sea Harbour YC
Oriental, NC USA
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The problem with brass in a saltwater environment or in contact with other metals is that it contains zinc. Yep… zinc, as in what we use for sacrificial anodes. A Joe stated, an internet search on the topic will yield plenty of specifics. Here’s two I found useful (one includes naval brass (AKA marine brass) that has tin added:
Yes V-drive. The photo was take from the port lazarette looking forward.
It does seem like the pump would need to be removed to get to the impeller… I wonder why they choose to use a pump like this one. The NS33 manual indicates that two pumps were used mine is a sherwood I forget the other brand.
I guess, at this point, instead of worrying about impeller replacement, I ought to be thinking a more broadly about propulsion system’s lifecycle. Maybe I don’t have that many impeller replacements left to do ?
Here is an exploded diagram of what I believe is the relevant Sherwood raw water pump from the Universal M-35 Owner’s Manual. I say relevant because the drawing shows the same pump cover and orientation as Rob’s photo. My question is whether the impeller can be accessed by removing the three bolts on the pump body back plate identified in the drawing as 21. If so, best to have new gasket 18 , o-ring 2, impeller 5 and glycerine on hand before starting.
Hi Ken,
The diagram you shared looks like the pump I have in Soave. I think the approach you describe is the best way to replace the impeller.
I guess with the version of pump we have, we need to remove the hoses before we can remove the impeller housing… adding to the mess and effort..
In addition to the parts you mention and depending on the hours on the pump, I’m wondering if it might also be handy to have a replacement pump cam if the old one is worn or damaged?
If you get to this project before me, please post your notes on the job. Especially if you see anything unusual. I’ll do the same.
I find Youtube to be a great how-to resource. Even when the videos were made by idiots, you can still at least see how things are put together. In this case the guy knew what he was doing and made a very helpful video:
From what I could see in the photo, it doesn’t look that hard to do. If you’ve not done it and don’t know how old it is, I’d do it now in your homeport rather then during a cruise. That diagram that someone sent is correct. They normally make kits that include all the parts you need. Always make sure you have a spare kit onboard including the gasket between the pump and the engine. As a retired mechanic, I’ve always preferred removing more easily removed parts then working in tight hard to reach spaces.
Joe Valinoti
S/V iL Gatto NS30U #221
Sea Harbour YC
Oriental, NC USA
While our boats are only two apart out of the mold and we have the same engine/transmission, my raw water pump is an original Johnson pump which requires removal of six small machine screws and the face plate to access the impeller. The machine screws are finely threaded requiring patience on installation to avoid dropping or damaging threads. I carry six replacement machine screws.
