IO-390-D Series Engine Maintenance Manual
12-10
© 2020 Avco Corporation. All Rights Reserved
Page 70
March 2020
IO-390-D Series Engine Maintenance Manual
WARNING
IF THE PRE-OIL PROCEDURE IS NOT DONE, HIGH-SPEED BEARING
FAILURE CAN OCCUR.
To complete the pre-oil procedure:
A.
If not already done, fill the oil sump with clean engine oil to the correct level per the “Add
Oil to the Engine” procedure in this chapter.
B.
Make sure that the Ignition switch, the Auxiliary Fuel Pump switch, and the Fuel Selector are
all in the OFF position.
C.
Fill the oil cooler with engine oil per the airframe manufacturer’s instructions.
D.
Disconnect the ignition leads from all spark plugs.
E.
Per the “Spark Plug Removal” procedure in Chapter 74-20, remove one spark plug from each
cylinder of the engine. Remove and discard the spark plug gasket.
F.
Move the throttle control to the FULL OPEN position.
CAUTION
DO NOT ENERGIZE THE STARTER FOR PERIODS OVER 10 TO 15
SECONDS. LET THE STARTER COOL FOR 30 SECONDS AFTER
EACH ENERGIZATION. IF THE STARTER FAILS TO ENERGIZE
AFTER TWO ATTEMPTS, IDENTIFY AND CORRECT THE CAUSE
PER THE AIRFRAME MANUFACTURER’S MAINTENANCE
MANUAL.
G.
Pre-oil start cycle: Energize the starter for 10 to 15 seconds and look for evidence of oil
pressure of at least 20 psi (138 kPa) within 10 to 15 seconds.
If there is no oil pressure within 10 to 15 seconds, stop energizing the starter. Wait at least 30
seconds and repeat the pre-oil start cycle.
Up to six consecutive pre-oil start cycles can be done. Afterwards let the starter cool for 30
minutes. If stable oil pressure is not achieved, stop pre-oiling and contact Lycoming Engines.
NOTICE:
Unstable oil pressure or oil pressure less than 20 psi (138 kPa) could be an
indication of obstructed or interrupted oil flow or air in the oil lines.
H.
If oil pressure of at least 20 psi (138 kPa) was sustained in the previous step, repeat the pre-
oil start cycle to make sure oil pressure holds stable and that there is not a sudden drop in oil
pressure. If oil pressure is not stable or drops suddenly, stop pre-oiling and contact Lycoming
Engines.
NOTICE:
Install a new spark plug gasket whether a new or acceptable re-used spark plug is to
be installed.
I.
Once the minimum oil pressure of 20 psi (138 kPa) is shown on the oil pressure gage, re-
install the spark plugs each with a new gasket as per the “Spark Plug Installation” procedure
in Chapter 74-20.
J.
Reconnect the ignition leads to all spark plugs.
K.
Within the next 3 hours start and operate the engine for 3 minutes at approximately 1000
rpm. Refer to the "Engine Start and Operation" chapter in the
IO-390-D Series Engine
Installation and Operation Manual.
