1948 case DI

[Royblizzard]

This 1948 DI tractor was running but the oil pressure would slowly drop from 20 to almost zero after about 15 minutes as it warmed up. Is this a pump or a bearing issue. Can I even get parts to rebuild this motor?

 

[mEl]

Your DI has shim adjustable mains and rods, if you have any mechanical ability and a good torque wrench you can remove shims to restore running clearance. If you take on the project be sure to remember the caps are directional, they are marked so be sure that they are put back up exactly as they were taken down. I always remove enough shims so it will not turn then add back what is needed. The knowledgeable ones would not like it that I have filed the rod caps when all the shims were out then added shims, and this on a motor that I ran turbocharged in competition for years. When you get it close, deleting a shim on one side only is permissible. Some use Plastigage but I think it unnecessary if you have any feel for this stuff. You will not be running into this in this operation but DC oil pumps from the factory are loose fit, when I redo a DC pump, I take the body down till the gears have a couple thousandths of clearance to the end plate. If I were doing your operation, I would remove the oil pressure relief valve plunger and inspect it for wear, they wear a pattern that is football shaped where the internal passages of the pump wear them, and it can be dressed off with emery paper to ensure that it won't stick. If you do this look at the spring for wear on the coil sides. If you do the relief, the pressure should be 35 lbs or close, and with a tight engine and pump should not vary cold or hot. To answer the last part of your post, the main bearings can be rebabbited to new , the bad part is they must be line bored in place, the rods can be rebabbited and sized to their journal at the babbiter. There is not a lack of good used parts out there and we have a couple on forum who can supply the kits and gaskets.