I have this Lister ST1, complete with electric start and alternator, that I am about to get running after many years of inactivity. I'm giving it a full service but before I go cranking the engine over I wanted to force fresh oil under pressure into the main oil way leading to the crank bearings, rather than wait for the pump to do its job. With a spotlessly clean high pressure oil can I pumped oil down the centre oil way that the filter screws onto, but the oil instantly just flows freely back out the small oil way to the left, that is the feed from the pump to the filter. I expected that once I had filled the oil way there would be resistance from the plain bearings and I could then generate some pressure while pumping the oil can to force fresh lube through the bearings. So why is the oil doing a short circuit? Are there ball valves or something built into the casing that maybe faulty? I have not come across this before. I know I could have just primed and fitted the new filter and then probably pumped oil through the hole above the filter after removing the small plug. But now I have discovered what may or may not be a fault, I cannot see why the oil feed to the filter would be connected to the main oil way after the filter. This would seem to allow the oil to bypass the filter, the oil filter already has a bypass valve buit into it, incase the filter becomes blocked. Honestly! You try and do a bit of good by making an extra effort and are rewarded with extra worry.