My car had a generic 'modern' plastic pump which worked fine but isn't
quite kosher so I got a new SU pump from Burlen and that is where I
discovered the diaphragm issue. It really does let quite a bit of
petrol smell through- enough for me to take it apart and look for the
leak. Burlen sent a replacement diaphragm which is, of course, no
better.
If you have a used 60 year old triple layer diaphragm for sale I'd be
interested in upgrading my new one!
The best design I have seen is an Italian copy that had a single layer
clear plastic diaphragm and also a plastic toggle inside the points
which is so much simpler than the mousetrap. Been in a Bn2 for longer
than I have been alive and only needed a replacement inlet fibre
sealing washer to stop a leak.
Andy.
On 11/23/16, Oudesluys <coudesluijs@chello.nl> wrote:
> I have not come across the single layer diaphragms. I have seen offered
> on ebay new dual layer ones from China and the UK. So far I have had
> enough scrap pumps of the wrong type to provide enough good triple layer
> diaphragms for the ones that were fit for a rebuild as the so called
> High Pressure type I want, AUF301 or W/AZX1307/8 or equivalent, so I
> have no experience with the modern replacements.
> The permeation of petrol will probably very, very little if any, so I
> would not worry about it. Some modern rubbers withstand all fuels and so
> as long as these are used it will probably be OK. Time will tell. Anyway
> the pumps cast iron coil housing and the space on top under the bakelite
> cap over the points assembly is vented.
> As the old triple layer diaphragms seem to last for ever I would not
> replace them other then when they have become hard and cracked or when
> the thin plastic membrane that keeps the petrol away from the rubber is
> damaged.
> Kees Oudesluijs
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