Lycoming IO-390-D Series Maintenance Manual page 122

Problem
High oil pressure
Sluggish propeller
operation
Engine does not
hold rpm during
cruise, climb, or
descent
Propeller goes into
feather during
landing rollout with
decreased power
setting
12-30
Page 96
Table 1 (Cont.)
Fault Isolation Guide
Cause
Relocated oil pressure
take-off point on the
engine
Oil temperature is too
cold
Oil pressure incorrectly
adjusted
Incorrect weight of oil
used
Oil passage is blocked
from the pressure relief
valve to the sump
Propeller oil control leak Complete the "Propeller Oil Control
Propeller oil control leak Complete the "Propeller Oil Control
Propeller oil control leak Complete the "Propeller Oil Control
IO-390-D Series Engine Maintenance Manual
IO-390-D Series Engine Maintenance Manual
Corrective Action
Use only the approved oil pressure
take-off point.
Before increasing the power control,
allow the oil temperature to increase.
Adjust the oil pressure by turning the
pressure adjustment on the oil
pressure relief valve.
Use the recommended viscosity of oil
for the ambient temperature per the
latest revision of Service Instruction
No. SI-1014.
1. Remove the pressure relief valve
from the engine.
2. Push a soft copper wire through
the oil passage to the oil sump to
remove blockage.
NOTICE: If blockage continues,
remove the oil sump and clean the
passage.
Leak Test Procedure."
Leak Test Procedure."
Leak test Procedure."
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Ref.
72-50
72-50
72-20
72-20
72-20
March 2020