NC SW6 Maintenance Instructions Manual page 72

CHART C4—Lubricating Oil pressure high
Cause
Incorrect lubricating oil. (specification of
viscosity).
Pressure switch or gauge fault.
Engine running too cold.
Oil pump pressure relief valve stuck closed.
Fault Finding
Make sure the correct lubricating oil is being used, Refer to Fluids
& Lubricants section.
Look for reduced viscosity from dilution with fuel. Fuel dilution in
lubricating oil can originate from fuel injection pump driveshaft
seal or fuel transfer pump.
Review/reduce the lubricating oil change intervals.
Verify the pressure switch is functioning correctly.
Refer to Chart D3.
Replace oil pump assembly.
Remedy
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