I had to replace my cam and lifters last year. I packed the oil pump with Vasoline to prime the oil pump. Ever since I did this last year, the gauge shows 40 psi at idle and maxes out while driving down the road.
This weekend I had to change my rear main seal and oil pan gasket. I knew my oil pump pick up was going to be dry when I started the engine up after everything was done.
I sat in the seat and watched the oil pressure gauge when I started it after the seal job was done. I knew the pressure would be low, so I wanted to see how low it was when it started and ran for the first few seconds. It seemed that it was at 20 when it was really dry, then after 3 or 4 seconds it jumped up to 40 psi. I took it for a spin around the block and it was the same again, 40 psi at idle and maxed out under normal driving speed. I have a few questions. Can the gauge be calibrated? It seems to be the stock gauge that came with the 79 AMC 304. Could it be a bad gauge or sending unit? Any help is much appreciated.
I am thinking faulty gauge, sending unit, or wires. Another reason why I only run mechanical gauges.
You can always pick up a mechanical gauge and hook it up to the block in place of the sending unit, never installing the gauge in the dash. Just sit it on the fender to test your motor. If it test shows good oil pressure, then you know the gauge circuit is faulty. If not, its in the motor. Cheap easy way to eliminate a few things.
Beat it to fit, paint it to match!