water pump rebuild

[Steve L.]

I've got my original 73 SB water pump that(813) I took out of service for many yrs due to a small leak. Now I want to rebuild it for the correct casting date.

I got a rebuild kit on ebay(dakoninc P1444-kit).
This kit has a sheet metal impeller while the original is a cast impeller.

I'd like to re-use the cast impeller, original fan hub. I'll use the new shaft and seals. Anyone know of a problem in mixing new and original parts?

[D S.]

Re: water pump rebuild

Bill Mock once rebuilt Corvette water pumps. Mockauto@aol.com

[Jim D.]

Re: water pump rebuild

There's probably a rebuilder in your home town that would do it for less than you paid for that kit. The local one in my town charges less than $50 with a 1 year warranty.

[Joe L.]

Re: water pump rebuild

I've got my original 73 SB water pump that(813) I took out of service for many yrs due to a small leak. Now I want to rebuild it for the correct casting date.

I got a rebuild kit on ebay(dakoninc P1444-kit).
This kit has a sheet metal impeller while the original is a cast impeller.

I'd like to re-use the cast impeller, original fan hub. I'll use the new shaft and seals. Anyone know of a problem in mixing new and original parts?

Steve-----


You can use the cast iron, original impeller if it's in good shape. In fact, I recommend that you do re-use it if you can. I consider the original cast impellers to be superior to the stamped steel type although others might feel differently.

I would use the new hub, though. Used hubs often loose some of the interference fit after removal and re-installation. They can also have excessive run-out after removal and re-installation.

A few things to be aware of:

1) While pressing the bearing in and out, the pump must be supported from the backing plate surface and NOT the legs. If you use the legs there's a VERY good chance you'll break the casting;

2) Clearance between the impeller vanes and body casting must be as specified in the overhaul manual. You won't find anything about waterpump rebuilding in a 1971 or later manual. So, you'll have to use a 1970 or earlier manual. Most (but NOT all) of the specs will be the same for the 1971 and later pumps. The hub spacing is one of the dimensions that will NOT be the same. Measure your original hub spacing prior to disassembly;

3) Achieving minimal run-out on the hub after assembly can be a trick. Too much run-out and your pulley will "wobble" and the pump (and fan clutch) will have a VERY short life.

[Steve L.]

Re: water pump rebuild

THanks all,
There is no auto water pump rebuild that I could find locally.

I've measured the clearance between the vanes and the body casting of the original as 0.030" Also the back of the impeller casting sits 0.015 proud of the backing plate sealing surface. I don't have acces to a 1970 manual. Either of the 73 service manuals have no info on the pump internals.

I've also measured the hub spacing as 5 13/16- which is different than what the Corvette magazine "water pump rebuild how-to" says (the only place I've found instructions on rebuilding). The impeller clearance of the sheet metal according the how-to is 0.010 to 0.013 which is again different.

Any idea what the max run-out should be?

Also the finish- Looks like there is no paint on the backing plate nor the fan hub. I'll re-use the backing plate since there are tabs on the original and none on the rebuild. I would imagine that the bolts would have paint only on the exterior faces since the whole pump was painted assembled onto the block.