IO-390-D Series Engine Maintenance Manual
© 2020 Avco Corporation. All Rights Reserved
12-30
March 2020
Page 91
IO-390-D Series Engine Maintenance Manual
Table 1 (Cont.)
Fault Isolation Guide
Problem
Cause
Corrective Action
Ref.
Engine surges (Cont.) Low engine oil level
Complete a check of the oil level. Add
oil. Refer to the sections "Oil Level
Check" and "Add Oil to the Engine."
12-10
Malfunctioning
propeller governor
Replace the propeller governor.
AMM
Breather is blocked
Examine the breather for obstructions.
Remove all obstructions.
Faulty oil pump
Replace the oil pump.
72-25
Propeller blades are
intermittently sticking in
hub
Remove and overhaul the propeller as
per the propeller manufacturer's
instructions.
Front main bearing has
too much clearance
Complete a “Propeller Oil Control
Leak Test.”
72-20
Irregular oil pressure Oil pump is sucking air
Replace the oil pump per the “Oil
Pump Removal” and “Oil Pump
Installation” procedures..
72-25
Low oil pressure
Oil not of the correct
viscosity for ambient
temperature
Make sure oil of the correct viscosity
for the ambient temperature is used.
Refer to the latest revision of Service
Instruction No. SI-1014.
Low engine oil level
Complete the "Oil Level Check"
procedure.
12-10
High oil temperature
Examine the engine for these
conditions:
1.
Low oil level
12-10
2.
Incorrect grade/weight of oil Refer
to the latest revision of Service
Instruction No. SI-1014.
3.
Oil cooler bypass valve seating and
operation
72-50
4.
Partial or full blockage in oil cooler
lines
5.
High cylinder head temperature
6.
Excess blow-by
7.
Blockage in air duct to the oil
cooler
8.
Non-conforming temperature gage.
AMM
