New Cast Iron Oil Pump pressure low

[JimT]

I can't speak for others, but my new oil pump, installed September this year, produces 25psi at idle (720rpm), about 36psi at 1500rpm and around 38-39psi at 1800-1900rpm.

One additional thing I did during my rebuild was to replace my oil cooler. Not sure if that had an effect on oil pressures, but I can say that my cold start oil pressures are now much lower then before the rebuild. Prior to rebuild I would have 40-ish psi at cold start idle with up to 55-60psi if I tried to drive before the oil warmed up (150F on the coolant temp). Now with the new pump I'll start out around 30-35psi at cold start at idle with a jump to maybe 40-45psi at 1500 rpm while cold. Oil pressure also normalizes much sooner without engine coolant temps needing to hit 150F.

edit: Cold starts/cold oil includes ambient temps ranging from 70F down to 25F. There has been no real difference in oil pressures due to the seasonal drop in ambient outside temps

I didn't shim anything on my pump.

Only thing I really don't like is the gear noise from this newer pump. Depending where you stand (especially toward the rear of the tractor) the noise from the pump can actually be louder then the engine. It did get quieter as the first oil got older, but once I changed it the noise got loud again. This oil hasn't yielded any noise reduction with age and it's almost time for another change. Hopefully the addition of gear lube with the next oil will help a little bit. And yes, the noise from the pump is always louder when the oil is colder, but not a massive difference.