Sunday, November 3, 2013

Field Overhaul of Sherwood R10870G, R50G, R30G Raw Water Pump

I had replaced my raw water pump some years ago and I finally managed to get a pump repair kit. I didn't have a fancy workshop with press, but instead had to make do with the tools I had on the boat. Here is how I set about reviving this old raw water pump.
First I removed the four bolts holding the cover plate on and extracted the rubber impeller. You can remove the impeller by using  needle nose pliers, holding an impeller blade opposite each other. Gently pull, alternating sides till it slides out.
Then I moved to the pulley end and undid the two screws holding the bearing and seal body to the main body.

Once the bearing body and shaft has been removed, remove the seal assembly. This will necessitate removing a small circlip on the shaft. Now remove the two woodruff keys. I use a pair of side cutters and gently grip at the base of the woodruff key and lever up. Be careful not to damage the shaft.
There is a woodruff key for the pulley and one for the impeller.

Remove the large circlip which sits in front of the bearing and drive out from the opposite end. Be sure to protect the end of the shaft from damage by using a sacrificial block of wood. The shaft is now free of the bearing and seal body.

Now, after removing a small circlip in front of the bearing, I used a bearing/pulley puller to pull the bearing off the shaft.

Puller with added socket on end of shaft

As the bearing came down the shaft, I used a small socket between the end of the shaft and the puller, to facilitate the last little bit to get the bearing off. You can see that in the picture to the right.

Now, replacing the seal surface is as simple as pulling out the old one with ones fingers and placing in the new one with a gentle push with the fingers. White side of seal (running surface) goes opposite the bearing and towards the sprung seal assembly.

In getting ready to reassemble, I cleaned off the matching surfaces of old gasket and proceeded to make a new one. For some reason my kit did not include this gasket. You can see the impression of the cut out to be, made in the gasket paper to the left of the pump body. Careful use of scissors and a hole punch made this easy work.
Now for assembly.....
First, I used a fine wet and dry sand paper to rub off all rust, nicks and burrs that were on the shaft.
With the one circlip on the other side of the bearing which was not removed off the shaft, I used this as the guide to which I would drive the new bearing on the shaft to. I used a small spark plug socket which was just the right size to slide over the shaft and seat against the inner race of the bearing. Using gentle taps with a hammer, I drove the bearing onto the shaft. It is important at the start of this, to make sure it is on square to the shaft as you make the first taps with the hammer. I finished with a piece of stainless tubing I had, to drive the bearing up to the circlip and then placed a new circlip on the other side of the bearing which keeps the location of the bearing on the shaft at the exact point needed. At all times, the force must only be applied to the inner race of the bearing. If you drive the bearing on using the outer race of the bearing, damage can be done to the bearing before it is even put to use.
Now place the shaft and bearing assembly through the bearing body and drive the assembly into the body by now driving on the outer ball bearing race. Small taps with a sacrificial block of wood and hammer will drive the assembly in till such time as you can now place the large retaining circlip which keeps the bearing/shaft assembly inside the bearing body.

Finally for the shaft, place on the spring loaded seal arrangement, compress the spring and place a new circlip to retain the assembly against the running surface. This can be seen assembled in the photo to the right.
With the gasket between the interfaces, present the bearing body to  the pump body and secure with the two threaded bolts. Mine were somewhat rusty, so I took the opportunity to put two new ones in with anti seize used on the threads.
Replace the two woodruff keys.
I didn't replace the cam inside the pump body: my kit had the wrong one and the old one was still OK. Also, I didn't replace the carbon bearing in the end of the cover plate. That was also OK, and while the carbon ones are easy to remove by breaking out from the recess, that can also be the demise of the new one when replacing; if one is not careful. These should be a finger push fit when done right, but heavy hands can also break these carbon bearings. Mine was OK, so I decided best to leave alone. After all, I'm not in a location where spares are easy to come by.
I leave the impeller out of the pump body until I'm ready to put it into service. I've seen too many pumps come off the shelf with impellers with distorted blades, just because they have been sitting in one spot inside the pump for many years.
The end cover was placed on the pump and the four retaining bolts finger tightened. Now it is wrapped in plastic and ready for the next time I have to replace the raw water pump due to leaking.
Hope that helps with your project.
Kit about $150 verses new at about $400. Time, about four hours.

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