The bottom line is just a basic drain line straight to the crankcase. There should be no pressure on that line.
If you have an air compressor, disconnect the line from the canister and blow through it, you should hear unrestricted air in the crankcase.
re. disconnecting the bypass oil filter. I've got a 235 engine ready to go into my 3100 whenever I decide to pull the trigger. It's never had a bypass oil filter and the return port on the block is capped and the oil pressure tap doesn't have a Tee for multiple line hookup, it just feeds to the oil pressure gauge. So if you want to remove the oil filter just cap the return ports, remove the Tee and connect the gauge line straight to the block. Don't run a line as it's not needed.
re. correct hookup of the bypass oil filter. Make sure the bottom return line isn't tapped into the pressure oil gallery that runs the length of the block. The gallery boss is clearly visable running fore to aft. The tap to the crankcase is mush lower in the block towards the front of the engine.
Good luck
Dave
