Replacing Sherwood pump - gasket sealant?

Mick Laver · April 16, 2013, 08:20:32 PM

I'm replacing the Sherwood pump on my M35BC. The old one is pretty corroded (see attached) and I figured it was time to bite the bullet. There seems to be some disagreement about whether or not to use a gasket sealant like Permatex on the seal when you replace just the impeller, but I couldn't find anything on the list about using sealant (or not) on the gasket when you replace the entire pump. Thanks.

TonyP · April 17, 2013, 03:19:46 AM

Mick
Looking at your picture, the Sherwood is way different to my Johnson raw water pump. We have a plate on the face with a gasket behind that I feel doesn't need a sealant as well. Each time I have removed the plate, the gasket is stuck to both faces and needs to be replaced.
Yours seems to have only 3 bolts holding the body (I see only 2, and from the rear) together so may need extra help sealing them together.
That gasket also look quite thick so should seal well under pressure. I presume the whole pump to motor gasket is the same so again should seal well under the pressure of those connecting bolts as well.
Going back to the picture, Yes the connecting body looks to be corroding on the external skin, but a good clean up/sand blast/acid wash I think would clean it up then seal and would be good to go for more years to come. It does look like rust. The main body looks like cast brass or bronze. The corroded connecting body looks like cast iron, hence the rusting. I do feel it is only the face though.
Others will add their comments soon.
As Stu says ... your boat your choice
Good luck

Tony

Roc · April 17, 2013, 04:09:33 AM

Mick,
When you replace the impeller, and change the gasket on the cover, no sealer is needed. Just install it dry. When you replace the whole pump, there is a round gasket that is used between the pump body and the engine. For that, Universal recommends using "High Tack" sealant. You can get it at an autoparts store. Spoke to Universal when I changed my pump and that's what they said to use. Follow the directions on the can.

Ron Hill · April 17, 2013, 06:07:26 PM

Mick : You shouldn't need anything if you replace the entire pump as the old gasket should still seal (no pressure).

If you replace the impeller only I'd look at the paper gasket on one side of the brass plate and the rubber "O" ring type gasket on the other. A bit of dishwashing soap will help you get the impeller seated and the pump around it.

If you happen to have another pump I'd install it and send your present pump to DEPCO. They will re build it and bake Zn Chromate coating on the iron portion of the pump body - call them 800-445-1656.

A few thoughts

Hawk · April 21, 2013, 06:31:56 PM

Mick,

I replaced my Sherwood pump with a new one this winter. I debated and then decided to put a relatively small bead of Permatex gasket sealant on, figuring it can't hurt...all looks fine with no leaks.

Hawk

Mick Laver · May 16, 2013, 03:37:09 PM

I finished this project a few weeks ago. Thanks for the tip on the gasket sealant. I got some from the local NAPA (see pic) and it seems to work fine. I sent the old pump to DEPCO and they totally refurbished it for $139, so now I have a spare. Probably easier to swap pumps in a seaway than try to replace the impeller; it certainly was that way for the Oberdorfers.

Speaking of. I have an Oberdorfer body (see pic) off my old 30's M25XP that I never got around to refurbishing. I won't be doing the Sherwood to Oberdorfer conversion on my M35B any time soon, so the old one is free to anyone who will pay the USPS postage. Send me a message offline.

Ron Hill · May 16, 2013, 03:54:33 PM

Mick : The sealant won't hurt, but I've never found it necessary, as there is a "paper" gasket that usually stays put on the engine side.

DEPCO, does a great rebuild job!! My thoughts

Stu Jackson · May 16, 2013, 04:44:49 PM

Quote from: Mick Laver on May 16, 2013, 03:37:09 PMProbably easier to swap pumps in a seaway than try to replace the impeller; it certainly was that way for the Oberdorfers.

Hmm...four bolts into the engine compared to either 1) swapping out a faceplate and an impeller which should be on a new shaft for backup anyway; 2) taking an entire pump off the engine.

Not sure that I wouldn't opt for (1) and, even better, a simple yearly impeller change.

Ron Hill · May 16, 2013, 05:41:02 PM

Guys : The only reason that I ever swap out pumps is because it's leaking, not just to change an impeller.

As Stu said - just change the impeller every year and 98% of your impeller problems are solved before they ever get started.

A few thoughts

Mick Laver · May 16, 2013, 08:38:58 PM

I'm not talking about maintenance. I do change the impeller yearly (at least I did on my 30's Oberdorfer - I've only had the 34 1.5 yrs). I still carried a spare pump on the 30, even though as Stu noted, the impeller replacement is trivial. We're all Boy Scouts (or Girl Scouts ... I'm not sure what their motto is.) We try to control what we can control. Stuff is going to break at the worst possible time, and I contend if it's dark, rolling, and nasty and you're operating at about 20% it's a lot easier to pull off a couple of hose clamps and four big bolts (two in the case of the Sherwood) and slap on a new pump than deal with the internals of either the Oberdorfer or (especially) the Sherwood.

Now how to deal with those things we can't control ...

reedbr · May 28, 2013, 08:10:55 AM

Can I ask where you got your Sherwood raw water pump and possibly the part #? I'm just starting my research on this. Last year at the end of the season I noticed some signs of oil around the shaft of my pump. This spring I see signs of rusty water in the same area. I've cleaned it up each time to try to identify the specific issue, but at this point I think I'm going to replace it to be safe.

Thanks.

Jim Hardesty · May 28, 2013, 10:22:52 AM

I just went through all that. Number switch and one source make it confusing. Here is where I got my pump, service was very good.
http://www.marinepartssource.com/newdetails.asp?mfg=Universal&pnumber=JHW42175
don't forget the pump mount gasket #UJHW-302678

Jim

reedbr · May 28, 2013, 11:34:22 AM

Thanks a second time Jim. It looks like you've been where I'm going on a couple repairs. How many hours on your diesel?

Jim Hardesty · May 28, 2013, 12:09:26 PM

475 hours.....about. My pump was just starting to weep. Couldn't tell it was till I had it off to change the impeller.

Ron Hill · May 28, 2013, 12:41:17 PM

Guys : All you need to do is look at the bottom of the pump while the engine is running. You'll see the water drip out of the bottom weep hole.

You can also put a piece of "fuel diaper" on the floor under the pump and check to see if it's wet after running the engine (incase you don't have door in the head to inspect the port side of the engine.)

Also drips do not mysteriously just go away!!