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Author Topic: Series 3 water pump seal replacement  (Read 719 times)
0 Members and 1 Guest are viewing this topic.
Posts: 13

« on: 25 October, 2020, 09:51:45 AM »

(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 didnít go according to plan so here is what I did.
If thereís a simpler solution Iíd 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 wasnít 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 Donís 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: 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, itís vital to get everything positioned so that there is some small pressure (it doesnít need a lot) holding the seal and face together. Itís easiest to do that after fitting the shaft and bearings and tightening the fan fixing nut Ė 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.


* seal and seat from China.jpg (263.39 KB, 1032x1014 - viewed 80 times.)

* bare pump body.JPG (874.66 KB, 1936x1936 - viewed 87 times.)
* Don Cross Tech Note Water pump overhaul.pdf (80.71 KB - downloaded 44 times.)
« Last Edit: 02 December, 2020, 08:20:05 AM by DaveKennedy » Logged
Permanent resident
Posts: 1353

Slow but rough

« Reply #1 on: 27 October, 2020, 10:35:05 AM »

Hi Dave
Looks like you have nailed this problem well and truly great work.

Fulvia Coupe S2 Flavia Coupe 1967 1.8 Kugelfischer Prisma 1.6 carb Y10 Fila Y10 Touring Dedra 1.8 Dedra 2.0 Turbo Appia S1
Senior Member
Posts: 119

« Reply #2 on: 01 November, 2020, 08:28:18 PM »

Ahh! I wished I'd read this before again, today, rebuilding the pump and putting it back on

I had the recess machined out a bit to take the seal and this housing and face is in good condition. I ran the engine and it seems to hold the water.

If it doesn't continue working, I will try this method 

1960 Lancia Appia Series 3 Sedan, 1966 Lancia Fulvia coupe, 1980 Suzuki FZ50, Bob Jackson bicycle.
Posts: 13

« Reply #3 on: 23 November, 2020, 09:04:55 AM »

Having now opened a pump where the old seal hadn't completely disintegrated, the originals were similar to the one supplied by the consortium. The seal was pressed into the recess with the ceramic face towards the impeller, then when assembled the impeller boss ran against that face.
I was originally told there was a hardened seat in the pump body and the seal was fitted the other way round - that's not right.

Simon's solution, enlarging the diameter of the recess, is best if you can get the machining done.

On the new seals there isn't much spring movement on the ceramic side, so the seal and the shaft have to be positioned accurately. There might be a better seal out there somewhere.


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