DocDirk If the guage has an electric sender to the gauge it is possible that the line as rubbed on a metal spot and cause the gauge to pin with contact to a ground source. Did you hear any rocker arm noise? Is the
oil filter shape expanded? At about 140 psi most filter blow apart.
Been there done that. If you are running a plastic tube to the
oil gauge in the dash, then you have a problem with either the pressure relief spring or a clogged
oil filter. Try to figure out which one you have first. We can then work this problem out. You may need a new sender in the block. Rick L. If you can get to the sender wire, turn on the ignition, without the motor running and see if the gauge jumps, if yes wiring issue. Turn key off and unhook wire from sender. Make sure gauge is at "0" reading, Touch wire to sender terminal and see if gauge moves, may or may not. Ground this wire to chassic and gauge should pin to max. If this checks out OK, I would buy a sender and replace. Make sure it MATCHES the GAUGE for the correct OHMS reading. IF not you will have some goofy readings. Is it an Autometer? They have a couple of different senders. Look for numbers on the sender to match up. Good Luck Rick.