In Reply to: Re: oil pressure posted by gary on June 27, 2020 at 14:33:13:
Also you do not need to line bore the engine for a new oil pump, only ream the new bushing."
The oil pump is part of the front main bearing cap and main bearing caps are matched sets that are manufactured and bored in situ on the block they are mated too. They will not interchange with another block or each other and must be installed in the exact position and orientation in which they were bored. That is a fundamental precept of engine building regardless of make or model.
If you replace the oil pump on an N series tractor you have to align bore the block to match the new cap to the block and other two main bearing caps. Failure to do so will result in an out of round and misaligned front main bearing housing which throws the crankshaft out of alignment on all mains. Failure to rebore and/or hone the block and caps is a real easy way to ruin a new crankshaft and main bearing set.
If you replaced the oil pump and did not align bore/hone the block and caps there is a real good chance your bearing failures and oil pressure woes are caused by front main housing out of round and misalignment problems.
If I were you I'd revisit that very critical area before you chance reaching another set of bearings and crankshaft.