(modified on 2nd December to correct a few things)
Fixing the leaking water pump was the first job after getting my 1962 Series 3.
It didn’t go according to plan so here is what I did.
If there’s a simpler solution I’d be pleased to hear it because I have a couple more pumps that need new seals.
Despite some good advice from Don Cross ( his tech note is attached ) three things were difficult:
- removing the screws holding the backplate to the body
- removing the pin holding the impeller on the shaft
- fitting a new seal.
OK, removing screws and pins are normal problems but I wasn’t expecting the seal problem.
This is what I found:
There seem to be at least 2 variations of the water pump that look the same externally.
One has a steel bush inserted in the pump body, and a ceramic-faced seal runs against that, with pressure applied by the impeller bush. This is the type shown in the parts list diagrams and in Don’s technical note. The 24mm dia seal supplied by the Consortium fits this type.
Another type has the seal inserted the other way round, with the ceramic face sealing against the impeller steel bush. There seem to have been at least two different sizes of seal fitted. It may be necessary to enlarge the recess in the pump body to fit the 24mm dia seal to this type.
Instead of machining the seal recess I bought a seal complete with seat from China (ebay link:
https://www.ebay.co.uk/c/1218719860 or look for 10mm x 22mm x 26mm Rubber Bellows Pump Shaft Sealing Mechanical Seal from newcentury22 and other China/Hong Kong sellers)
The ceramic seat from that seal, in its neoprene mount, is 22.5mm OD and fitted neatly into the recess. I smeared some silicone grease on the underside to make sure it sealed well. I then used the Consortium seal but equivalents are on eBay.
Whichever way you do it, it’s vital to get everything positioned so that there is some small pressure (it doesn’t need a lot) holding the seal and face together. It’s easiest to do that after fitting the shaft and bearings and tightening the fan fixing nut – then the shaft will be in its final position and you can work out how much space there is between the seal recess and the impeller. You may need to cut down the impeller bush if it's too long or add washers if it's too short
A few photos are attached. I fitted new bearings too and the pump has been working for 3 months now with no problems.
Dave
