Crankcase Disassembly - Lycoming IO-390-D Series Maintenance Manual

3. Crankcase Disassembly

Put the crankcase upright on a suitable work
A.
surface
Crankshaft Idler Gear and Bushing Removal
B.
(1) Remove the idler gears and bushings (Figure 2)
from the idler gear shafts.
(2) Discard the bushings.
CAUTION
Use a slide hammer, a Crankcase Thru-
C.
Stud Puller ST-271 or Crankcase Thru
Stud Driver ST-317 or a plastic hammer
to remove the four thru-studs from the
crankcase (Figure 3).
Remove the remaining bolts and nuts
D.
that attach the crankcase halves.
Insert one used pushrod into each of the
E.
four holes where the thru-studs were
removed to support the camshaft and
crankshaft when the crankcase halves are
separated.
Separate the crankcase with a Crankcase Separating Tool ST-389 or with a slide-hammer
F.
attached to one of the base studs as shown in Figures 4, 5, and 6.
Figure 4
Attach the Slide-Hammer
to a Base Stud
72-20
Page 130
TO PREVENT DAMAGE TO THE CRANKCASE, REMOVE ALL THRU-
STUDS, NUTS, AND BOLTS FROM THE CRANKCASE HALVES
BEFORE SEPARATION OF THE CRANKCASE HALVES.
Strike the Slide Part of the Tool
Against the Back of the Tool
IO-390-D Series Engine Maintenance Manual
IO-390-D Series Engine Maintenance Manual
Crankshaft Idler Gears
Crankcase Assembly
Figure 5
© 2020 Avco Corporation. All Rights Reserved
Figure 2
Figure 3
Figure 6
Separate the
Crankcase Halves
March 2020