[Lister-FR] a leaking centrifugal circulating water pump

Simon Kelley simon at thekelleys.org.uk
Sat Apr 18 20:00:08 BST 2009


John Clive wrote:
> Simon
>  
> I think you emailed me some time ago,
>  
> Do you know anyone who knows how to "fix" a leaking centrifugal 
> circulating water pump?
>  

Well, I fixed mine.

Here's a "brain dump" of what I learned, doing it.

I assume the leak is from one or both of the weep-holes in the pump 
casing. Don't just block these holes (as someone had done on mine) you 
risk diverting the water into more destructive places (like the crankcase).

The shaft through the pump is sealed at each side by a carbon seal which 
runs on a machined surface in the casing. There is an O-ring which stops 
seepage between the shaft and the carbon seal.

There seem to have been two designs, in the earlier one the carbon seal 
is driven from the shaft just by friction on the O-ring. In the later 
design there is a brass driving dog on the impeller which engages with 
slots on the side to the carbon seal to ensure a positive drive. My pump 
is of the later design but I have drawings for both.

New carbon seals were available a couple of years ago from Sleaman and 
Hawken.

If the machined faces in the casing on which the carbon seals run are 
worn or corroded, even new seals will not work. I had the casing 
re-machined by Peter Thompson an Marine Engine Services in Uxbridge 
which did the job fine.

Dismantling requires a puller to get the drive-gear off the shaft but is 
otherwise not difficult.

I guess that a best-case might be that just the O-rings need replacing.

If you're not up for doing the job yourself, I'm sure Peter Thompson 
would quote for it.

Cheers,

Simon.





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