1930’s MG Oil Pump Flange

image of MG car oil pump flange, close up above

This oil pump flange (from a mid 1930s MG K type) was found at a vintage auto-jumble by one of my regular customers. It was in a bad state. The mounting face was pitted and, worse still, the oil pressure control piston was jammed deep inside the flange. It was in the ‘last chance saloon’ as all attempts to remove the piston had failed. I was asked to remove the piston and tidy up the flange for re-use. If possible without damage to the piston or the flange! My first attempt to remove the piston by pressurising with compressed air through the rear oil port had no effect. Looking down at the back of the piston, carbonised oil could be seen this was hard and was jamming the piston in. The engine that this oil pump flange had been on had probably been run with filthy oil (no oil changes) and had almost certainly seized up. I noticed that the oil pump piston had a deep rear recess. So a made a steel plug to fit in snugly. With a bit more juggling I got the plug tight enough into the back of the piston to enable me to just pull out the piston. No damage to the flange or the piston. The carbonised oil that was jamming the piston was cleaned off and the piston bore was found to be serviceable. A quick skim (0.008 inch / 0.2 mm total, in stages) off the mounting face and the flange was ready for action again.