Hi all,
I just thought I let anyone who offered help re my previous post know where we as of just now. ;-)
Recap. Bambi 75/150 Silent compressor, not been used for a few years, now slightly leaking (back into the pump) and the pump not starting back up when under pressure.
I removed the one_way_valve between the pump and the tank/pressure switch and found it was a simple spring loaded rubber 'bullet' that was gently pushed into it's conical seat by a reasonably light spring, opened simply by the pump pressure.
When the pump stopped the valve leaked air back from tank to pump 1) loosing tank air pressure and 2) stopping the pump from re-starting (till the pressure dropped to about 40 psi).
The cause seemed to be an indentation across the sealing face of the rubber 'valve' (probably caused by some long-term trapped debris).
I had been considering different ways to gently and symmetrically re-face the valve but being only 10mm diameter and 10mm long (and rubber) it wasn't that easy, till just now. ;-)
I was doing something else and dug out a hex drive socket set and found said rubber valve fitted quite nicely inside the 9mm hex driver. I put that in the variable speed drill and after a bit of manual re-centering, used various grades of paper (down to 240) to do the re-facing.
I put the valve back together (using an O ring as designed, not the PTFE tape as I found it) but it was still leaking back *slightly*. Partially releasing the pipe from the pump to the valve, bleeding off the pressure in the hose seemed to stop it leaking completely (probably the increased pressure on the back of the valve). The pump would also restart after this procedure (there is no dump valve on this design because it would be too noisy).
I stripped the valve again and slightly stretched the compression spring to apply a bit more pressure to the valve [1] and that has seemed to have done it! ;-)
When the pump switches off you can still hear some air leaking back into the pump but that is simply the pressurized air trapped between the pump and valve relieving itself (ready for the next re-start).
I'm glad I seem to have sorted it as a new valve was 19 quid but the postage another £19 (it could have been £30 as there was a minimum order of £50)! :-(
Anyway, all the best and thanks again. ;-)
T i m
[1] If it starts to leak again I'll probably look for a replacement spring.