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