Rebuilding a Sherwood raw water pump

[Ron Hill]

Guys, Susan and D. Gill : I just took apart a G908 Sherwood pump (like is on the M35BC engine) and rebuilt it. Not that difficult!!

It took me about 2 hours, but then I was in unknown territory.  Now that I have done it; I could do it on the boat in maybe in 1 hr (for those that like to suffer) or take it home on the workbench and do it easily in < 15 minutes.

I found that you don't have to destroy the oil seal to replace the water seal and you don't need to make a special tool, which makes things easier than with the Oberdoffer. 

I'm sure others have rebuilt theirs, so I surely am not the first.   A few thoughts

[Jack Hutteball]

Ron, it sure would be nice to have a photo essay of your rebuilding process.  I have one sitting on my workbench that I could work on.

Jack

[Roc]

Also, what kind of tools are needed to do such a job.....

[Ken Juul]

When I looked at rebuilding mine, this was probably 6 years ago, the critical part was the shaft.  Mine was scored beyond reuse.  The shafts were very hard to find, thus cost as much as a new pump. Perhaps that has changed now.  Also for an emergency repair on the boat, I could see not replacing the oil seal, but for a couple dollars (if that) why not replace it so you have a completely rebuilt pump.

[Ron Hill]

Jack : I'll send you a little write-up.

[Ron Hill]

Roc : I just used the tools that I had at hand. 

I didn't have to make a special tool like I did to rebuild an Oberdoffer!

[TonyP]

I sucked up some weed on the weekend but my first thoughts were the raw water pump.
We have a Johnson (made in Sweden), which looks a very simple pump.
I removed the face plate, ruining the gasket, popped out the impeller, replaced with new one we had onboard, made a gasket out of a magazine page (temporary till I get some real gasket paper) them back together to find still no water.
Later found no water coming through the inlet filter so dived overboard to find it was blocked at the inlet under the hull.
Lesson learned... try the easiest options first.
I have only read about Sherwood and Oberdorfer pumps here.
Do others have a Johnson?

cheers
Tony

[Ron Hill]

TonyP : Been there done that twice - mine was sea-grass or hydrilla.

After that happens the first thing, what anyone should do is to check the raw water flow.  Remove the raw water inlet hose from the thru hull.  Then slowly open the thru hull.  To my surprise NOTHING came out/ not a drop. 
Wrote this up many years ago and that is the reason to carry a 3/8" wooden dowel onboard. I poked it out from the inside.   A thought

[Ron Hill]

Ken : When the raw water pump shaft is scored you are SOL (and I don't mean Standards Of Learning!).

Usually the shaft is not scored except when you do something unknowingly stupid as I did. 
I was on the ICW and decide to follow a tug boat.   Because -- They come up and the bridge opens because they are commercial traffic!! 
The tug I was following too closely came to a shallow spot and "kept on a trucking" churning up the bottom. There was silt/sand etc. everywhere in the water and I was motoring thru it. 
The end result was that I chewed up the cutless bearing and the shaft on the Oberdoffer with all of that sand going thru the system.

Lesson learned, don't follow a tug!!   A thought

[Stu Jackson]

TonyP : Been there done that twice - mine was sea-grass or hydrilla.

After that happens the first thing, what anyone should do is to check the raw water flow.  Remove the raw water inlet hose from the thru hull.  Then slowly open the thru hull.  To my surprise NOTHING came out/ not a drop. 
Wrote this up many years ago and that is the reason to carry a 3/8" wooden dowel onboard. I poked it out from the inside.   A thought

Good point.  You can also remove the intake hose from the raw water pump and use a dinghy foot pump to blow it out.  Sometimes...depends on what the clog consists of.

[TonyP]

We have a bloody big filter on top of the through hull and I couldn't remove it. I did 2nd as Ron suggested and removed the hose (which on inspection probably could do with replacing as well) and saw that no water was coming through, and as I couldn't get to it from the inside, the only other way was the wet way, about 15 degrees C

[Ed Shankle]

Ran into the clogged intake through hull this past weekend. The dowel solution doesn't work for me because of the type of strainer that I have. After unscrewing the bowl, it's a 90 degree angle to go down the through hull. I assume others have the same issue. Need something that will bend, like a wire brush bottle cleaner. I had one, but still couldn't push past the last half inch. I assume it got caught up on an edge, but not sure. The dingy foot pump solution didn't work either. Had no choice but to go over the side with a screwdriver and my bottle brush. So I'll either have to change my strainer type or experiment with different types of brushes to determine what works best.
I guess the lesson is, do a dry run before assuming the solutions offered on the board will work for your boat. Although I don't know how I would have done an effective dry run with the foot pump.

Ed

[Stu Jackson]

Ed, I have the same arrangement.  The strainer is screwed directly into the thru hull.  One thing I've considered is simply relocating the strainer by inserting a short piece of hose between the thru hull and the bottom of the strainer.  We don't seem to have the same amount of debris in the waters here.  I've had only two blockages in 14 years.

[Ed Shankle]

Nice idea Stu, thanks. We don't seem to have it too bad around here either, but it seems whenever someone writes about a problem they have, it soon happens to me! I pray no one writes that their boat blew up!

regards,
Ed

[MarkT]

Try using the foot pump for inflating your dinghy to blow air back through the thru hull. I can't tell from your signature whare you may be in the country but if it is a jellyfish or weed then this might clear the blockage.

Mark T