Impellers

[stickandrudderman]

OK, I've answered my own question.
There's a brass bellows that slides over the shaft which is locked to the shaft by a locking plate and circlip.
The "O" ring on the shaft seals inside that bellows to prevent the passage of fuel up the shaft, into the motor body and out through the two small vent holes.

[PeterPortugal]

Colin,

Those two inserts, and the holes in the side of the casing, are above the hole which allows leakage out to the little pipe stub. To go back to your original question it is still not easy to understand why fuel would come out of the holes in preference to the pipe.

I will be real interested in the answer if anybody does come back with one.

Regards

Peter

[thelews]

OK, I've answered my own question.
There's a brass bellows that slides over the shaft which is locked to the shaft by a locking plate and circlip.
The "O" ring on the shaft seals inside that bellows to prevent the passage of fuel up the shaft, into the motor body and out through the two small vent holes.

Correct.  There is a write-up in the tech section with pictures

[BaronYoungman]

I wish I could help regarding the long pumps.  I have tried working on them in the past but I have been frustrated  with the system, so I've just concentrated my efforts on the short pump, which due to its design and materials I can guarantee performance and tight seals.  By applying more modern materials and Technology in both Viton gaskets and improved techniques / glues for Armature rewinding I have actually improved on the original designs. Although again I'm improving on a design that has lasted in some pumps 40 years plus which I'm always amazed by when I get them to rebuild.  Some have never been taken apart since they left the factory.  This just demonstrates a good and robust original design of the pump. Bob