I have a high mileage engine and the Oil Pressure gauge shows much lower than spec oil pressure. At idle almost nill.

So far no damage. The engine has had lots of maintenance and the top end (heads) I know have been reworked.

Is it common for the 3.0 oil pump to wear out or am I more likely looking at worn bearings and a need to rework the crank and replace main and rod bearings?

This is my 1st experience with the Mitsubishi 3.0!

 

may help if you tell us what year you're driving.


but chances are it needs nothing. Mitsu v6s NEVER wear out unless neglected or abused.

 

dirty engine oil can cause the reading to be lower than normal.
another possible cause is the oil pressure sensor but this sensor hardy fail.

 

Maybe you have dirt built up inside the engine? How many miles on it?

 

where is the oil pressure switch located in a 2000 montero sport v6 3.0?

 

at idle the spec on that motor is 9 to 11 psi when warm.