How to install water pump impeller w/o pulling shaft?

Because I have read that it is possible to damage the seals on my Oberdorfer pump when pulling the impeller shaft (the easiest way to change the impeller and the reason I keep a spare impeller mounted on a spare shaft), I bought an impeller puller which works great when removing the impeller. However, when I replace the impeller the shaft is just a hair too short to allow me to push the impeller on far enough to seat the snap ring with the result that I have to pull the shaft out anyway. Does anyone have a similar problem (and solution)?

one way

I replaced my old Sherwood and went to the Oberdorfer two years ago. I lightly tap the rim of the impeller with a rubber mallet on a flat-head screwdriver to seat it. The snap ring then fits fine...well, it is still tricky but I can get it on. This has worked well for me. Having looked at the tight fit of the carbon seal, I can see how you could score it when pulling out the shaft.

Thanks Chris, I'll give that a try next time. I had my seals replaced because of a leak, but then found that the problem was wear on the shaft from the seals. Replacing the $50 shaft cured the problem. I now keep the old shaft with an impeller already mounted in case of emergency. I can't see fooling with that snap ring if I have to change the impeller in a hurry.

i hope that i am not damaging the seal...
i pull the impeller while holding the shaft in place with a screwdriver. when i put a new impeller in i lube it and the shaft a little with dish soap. then i pull the shaft out about 1/8" and slide the impeller on. that way when the impeller is all the way on i still have room to get the snap ring in place. i've never pulled the shaft all the way out. do you think that moving it as much as i do will score the seal / shaft?

I think the concern is that the end of the shaft will somehow knick the seals. The shaft revolves millions of times against the seals. I can't see how sliding it back and forth laterally would be any different. How do you manage to pull yours out just a little once the impeller is in place? What do you grab onto and with what?

Remove rough edges

When you remove the shaft, inspect for burrs and sharp edges. Where the shaft is slotted on the end, the edges get hammered out during use. Take a small file and chamfer the edges back about 1/32" to 1/16", then take a piece of emory cloth and polish the shaft. Use a motion similar to polishing your shoes around the shaft. This will help prevent damage to the seals. Another trick is to wrap 0.010" shim stock around the shaft, insert the shaft through the seal then carefully remove the shim stock.

Geoff Johnson said:

How do you manage to pull yours out just a little once the impeller is in place?

Click to expand...

i can't. i slide the shaft out about 1/8" before i put the impeller on. with some lube and finesse the impeller slides on to the shaft without pushing the shaft back in (very much). so when the impeller is all the way on the shaft is still out enough to get the snap ring on.

Incorrect

I just changed my impeller last night, and, Geoff, you were right! The snap ring just didn't fit on the shaft. When I talked about the tapping I must have done that on the Sherwood pump. I know for a fact that I never pulled that shaft out.

After futzing around for a bit I finally just pulled the shaft out and put the impeller on (with bronze rings front and back and snap ring). The aft aedge of the shaft is already beveled but I still took out the 600 grit paper to make sure there are no burrs. I then wiped the shaft clean and oiled it lightly with motor oil before CAREFULLY reinserting it through the seals. While I don't like to do it this way I just found no other possibility to get the snap ring on the front of the shaft.

Chris