Advertising and Classifieds => Douglas Motorcycles and Parts Wanted - Private => Topic started by: Clive on 21 Nov 2011 at 20:29

Title: Oil Pump
Post by: Clive on 21 Nov 2011 at 20:29
Hi Everone ,
The oil pump on my 1930 b31 has badly corroded internals, it pumps oil cold but is very sick when hot hardly lifts the indicator .  My question is does anyone have a spare to sell or just the vanes and spring would be a help The Douglas club spares cant help so hoping someone out there has a box of bits they could sell me .
Title: Re: Oil Pump
Post by: coles1933 on 07 Dec 2011 at 16:23
Hi  I remachine oil pumps of the postwar series ( Holbourn Eaton rotary pumps) to get away from wear
problems and to increase both pressures and flow volumes. I dont know your older pump but if it is a
rotary vane pump I may be able to help you Regards coles1933 UK.
Title: Re: Oil Pump
Post by: Clive on 07 Dec 2011 at 20:26
Hi Coles,
Thanks for the reply , yes it is a rotary vane pump of the simplest design . The housing is badly pitted [40 yrs under a hedge] full of water etc. I have attempted to fill these holes with epoxy filler [metal set] and have had a limited success but the pumping efficiency has suffered ,pumps cold oil but hot not so good . you say you machine out the housing which means you would have to make a new shaft and rotor , i am not sure how much meat there is in the case for removal .  At the moment a friend has the pump so i cannot photo or measure it.
Will get back to you as soon as the pump returns home
Title: Re: Oil Pump
Post by: coles1933 on 08 Dec 2011 at 09:08
Hi Again I have been re- working these pumps for 7-8 years and have 40 or so being used now, I keep the Mark version in stock modified and ready for exchange or if douglas owners wish to keep their own pumps I modify them. I have an Alexander die sinker and a rotary
table with which I can increase diameters in 0.0005" increments, normally all that is required is 3-5 thou removed on diameter and the
same on depth (sometimes zero on this dimension) the cutters have to be the best available tungston carbide and the finish down
around a few microns. It is not necessary to re-make the shaft and rotary unless you have wear on the bearing surface and your
pressure getting away here. The jigging for the pump is quite elaborate but could be done by any good machinist with a CNC
machine. The pump cover quite often requires lapping to get a good flat surface as you can loose pressure and flow here very easily
the end of the pump face needs grinding or lapping to get the clearance to the vanes correct. I carry out this work for a very modest
25  if only the diameter needs attention more if it needs more work.  You can now use this to get it done yourself or I will be happy
to do it for you. Just remember one force move and the pump could be junk. Regards coles1933