Chrysler 1991 Service Manual Supplement page 67

9 - 4 5.9L (DIESEL) ENGINES
SERVICE DIAGNOSIS • MECHANICAL (CONT.J
CONDITION POSSIBLE CAUSES CORRECTION
LUBRICATING OIL
PRESSURE TOO HIGH
Pressure switch/gauge not
operating properly.
Verify the pressure switch is functioning correctly. If not,
replace switch/gauge.
Engine running too cold.
Refer to Coolant Temperature Below Normal (Engine Diagnosis—
Performance)
Oil viscosity too thick. Make sure the correct oil is being used. Refer to Group O,
Lubrication and Maintenance.
Oil pressure regulator valve
stuck closed or binding.
Check and replace valve, and/or oil cooler cover.
LUBRICATING OIL LOSS External leaks. Visually inspect for oil leaks. Repair as required.
Crankcase being overfilled.
Verify that the correct dipstick is being used.
Incorrect oil specification or
viscosity.
(a) Make sure the correct oil is being used.
(b) Look for reduced viscosity from dilution with fuel.
(c) Review/reduce the oil change intervals.
Oil cooler leak. Check and replace the oil cooler.
High blow-by forcing oil out
the breather.
Check the breather tube area for signs of oil loss. Perform the
required repairs.
Turbocharger leaking oil to the
air intake.
Inspect the air ducts for evidence of oil transfer.
Repair as required.
Worn valve seals.
Inspect and replace the valve seals.
Piston rings not sealing (oil
being consumed by the engine).
Perform blow-by check. Repair as required.
COMPRESSION
KNOCKS
Air in the fuel system.
Poor quality fuel.
Bleed the fuel system (refer to Group 14, Fuel System).
Verify by operating from a temporary tank with good fuel. Clean
and flush the fuel supply tanks. Replace fuel/water separator
filter.
Engine overloaded.
Verify that engine load rating is not being exceeded.
Incorrect injection pump timing. Check and time injection pump (refer to Group 14, Fuel System).
Improperly operating injectors. Check and replace inoperative injectors.
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