Water pump refurbishment

Tools required for this job, other than the socket/spanner to remove the pump are: good quality gear puller, long reach sockets, hammer and wood (persuader), internal and external circlip pliers, wire brush, wet and dry sandpaper.

I could now turn my attention to refurbishing the pump body and would obviously require a new shaft. Fortunately, there is a shaft kit available which includes two new bearings, spacer and retaining circlips, but bizarrely only one seal.

However, as I’d already bought the overhaul kit, I had two seals, as well as two more bearings and circlips, cover plate, bolts and main body O-ring so I was well covered. Interestingly neither kit came with the plastic seal spacer and small O-ring so I re-used the original spacer and sourced an O-ring from my stores.

Step by step

1

With the help of my cheap extractor, a hammer and some wood, I was able to remove the old shaft and associated fittings from the pump body, and it became clear this was long overdue. The fact I now had a new shaft saved me from having to try and get this rusty mess apart, but I did manage to get the first seal off to free the spacer.

2

The mating face on the body required a bit of a clean-up and I felt doing it now before the bearings were installed was the ideal time. I used a very flat cutting board with a silicon mat to prevent contamination and a few different grades of oiled waterproof sandpaper, going down to 1,200-grit to get a perfectly flat surface.

3

The bearings are a very tight fit onto both the shaft and the body. I could have cooled the shaft in the freezer to get the bearings on, but there would then be the challenge of pushing two bearings into the body at the same time. Instead, I used a socket and the gear puller to push the seal then the first bearing home into the body from the gear end. The socket ensures the seal was set to just the right depth and allowed the bearings to be pushed in without damaging them with excessive sideways force.

4

The shaft was pushed in from the impeller end to just past its final location, and the small circlip fitted from the gear end before pushing the shaft back to its final position. This was not that simple as getting the shaft through the bearing resulted in the bearing moving, so it needed to be reset a couple of times. The bearing spacer could then be popped on (it’s a loose fit) before the second bearing was pushed home, again using the socket and gear puller. The large circlip could then be installed so the shaft and bearings were now correctly seated into their final positions.

5

The seal spacer, with the lugs pointing towards the gear end, and small O-ring could then be inserted before the second seal was pushed home, again using a socket to set the depth correctly.

6

The rescued gear could now be fitted to the tapered end of the shaft. A few gentle taps of the hammer with a block of wood to locate it and stop the shaft rotating, enabled it to be torqued down to 50Nm. The gear was clamped in a vice with lots of protection in the form of wooden blocks and rags. While there is a lock washer, I also added some medium strength Loctite for good measure. No nut is included with either kit, but it’s a common M10 thread, and as the original nut was damaged, I sourced a new one from my box of stores.

7

Finally, the new faceplate was fitted with the new machine screws, but the impeller was not fitted at this stage. I anticipated needing to ‘wiggle’ the shaft when re-fitting the pump to get the gears to mesh so it made sense to hold off installing the impeller. I’ll also wait until the pump is installed on the engine before repainting to ensure no paint gets on the mating surfaces.