Operator`s manual

OVERHAUL
MANUAL
LYCOMING
DIRECT
DRIVE
AIRCRAFT
ENGINES
Section
7
Crankcase,
Crankshaft,
and Reciprocating
Parts
SECTION
VII
CRANKCASE,
CRANKSHAFT
AND
RECIPROCATING
PARTS
7-1.
At
this
time
it is
assumed
that
all
accessories,
cylinders,
accessory
housing
and
sump
have
been
re-
moved
from
the
engine.
DISASSEMBLY
7-2.
Starter
Ring
Gear
Support
-
Remove
the
starter
ring
gear
support
assembly
(32,
figure
7-5)
from
the
crankshaft
propeller
flange
by
tapping
lightly
on
the
rear
face
of
the
assembly.
The
alternator
or
generator
drive
belt
will
be removed
with
this
unit.
7-3.
Propeller
Governor
Oil
Line.
(Engines
equipped
with
propeller
governor
on accessory
housing.
) If
this
line
was
not
disassembled
when
removing
the
acces-
sory
housing,
remove
from
the
front
of
the
crankcase
by
unscrewing
the
threaded
fitting.
7-4.
See
figure
7-5.
Remove
the
crankshaft
idler
gears
(22)
from
the idler
gear
shafts
(29).
On
engines
em-
ploying
camshafts
with
separate
gears,
remove
the
breather
slinger
(19),
camshaft
gear
(14),
and
tach-
ometer
shaft
spacer
(18)
by removing
the 4
hex
head
bolts
(21)
and
lockplate
(20)
securing
the
assembly
to
the
camshaft.
Remove
the
tachometer
drive
shaft
(16)
by
removing
the
pin
(15).
See
figure
7-6.
On
engines
using
integral
camshafts,
remove
the
retaining
ring
(14)
and tachometer
shaft
spacer
(13).
Remove
pin
(11)
and
tachometer
shaft
(12).
7-5.
Remove
the
nuts
and
bolts,
from
the
parting
sur-
face
of
the
crankcase,
which
hold
the crankcase
halves
together.
Remove
the
crankcase
from
the
overhaul
stand
and
place
on
the
work
bench.
7-9.
From
this
point
disassembly
is
the
same
for
all
crankcases.
Reach
down
through
the
cylinder
pads
and
push
the
left
half
of
each
main
bearing
insert
down
on
the
crankshaft
so
they
will
not
fall
when
the
crankcase
half
is
removed.
Separate
the
crankcase
by hand
and
remove
the
bearing
inserts,
tappets,
camshaft
and
crankshaft
assembly.
Place
each
tappet
body,
as it
is
removed,
in
its proper
location
in the
cleaning
basket.
This
is
important
as
tappet
bodies
must
be
replaced
in
the
same
location
from
which
they
were
removed.
NOTE
In
the
left
crankcase
half
the
intake
tappet
for
its
corresponding
cylinder
is
located
nearest
the
front
of
the
crankcase,
while
in
the
right
crankcase
half
the
intake
tap-
pet
is
nearest
the
rear
of the
crankcase.
7-10.
Propeller
Governor
Drive
(Located
on
front
left
side
of
crankcase).
See
figures
7-3
and
7-4.
Remove
the
hex
head
plug
(6)
and
gasket
(5) from
the
propeller
governor
housing.
Remove
the
idler
shaft
(4)
through
the
opening
in the
housing
at
the
same
time
supporting
the
idler
gear
(9)
to
prevent
dropping
and
damaging.
Note
that
the
idler
shaft
on
four
cylinder
engines
is pin-
ned
to the
housing.
Pull
the
governor
driven
gear
(8)
from
the
housing.
7-
11.
Crankcase
- Remove
allthreaded
plugs
to
facili-
tate
cleaning.
Remove
and
discardthe
rubber
oil
seals
encircling
the
studs.
(Doweled
crankcases
do
not
em-
ploy
oil
seals
at
the
dowels).
Where
applicable
re-
move
the
piston
cooling
oil
jets
(17,
figure
7-1).
7-6.
Remove
oil
filler
tube.
See
figure
7-1.
Remove
oil
pressure
relief
valve
assembly
(23
or 24).
Remove
oil
seal
retainer
plates
(19)
(used
on engines
that
do
not
have
crankcase
modified
with
machined
groove
to
accept
oil
seal
with
retaining
lip
on
OD).
7-7.
Hydro
Control
Valve.
(0-235,
0-290
series.
Where
applicable.)
See
figure
7-15.
Remove
cotter
pin,
slotted
shear
nut
and hex
head
screw
and
remove
lever.
Remove
the
two
1/4
inch
bolts
securing
the
cover
tothe
crankcase
and
remove
the
cover
and
valve
body.
7-
8.
Crankcases
that
are
doweled
at
the
thru-
studs
(#2
saddle
on
4 cylinder
engines,
#2
and
3 saddles
on
6
cylinder
engines
and
#2 -
3 and
4 saddles
on
8 cylinder
engines)
must
be
separated
by
the
use
of
pressure
plates
(ST-122).
Instructions
for
the
use
of
the
plates
are
given
in figure
7-16.
After
the crankcase
is sepa-
rated
past
the
dowels
remove
the
plates
and
lay
the
crankcase
on
the right
side.
Crankcases
that
are
not
doweled
may
be
separated
by
laying
on the
right
side
and
gently
tapping
the
thru-studs
with
a
soft
hammer.
Wire
the
camshaft
to the
left
crankcase
half
as
shown
in figure
7-2.
7-12.
Remove
the
two
crankshaft
idler
gear
shafts
from
the
rear
of the
crankcase
halves.
On
the
eight
cylinder
engines
remove
also
the
two
magneto
drive
gear
shafts.
7-13.
CamshaftGovernorDriveGear
(6
and8
cylinder
engines
using
camshaft
with
separate
gears).
See
fig-
ure
7-5.
Remove
the
governor
drive
gear
(2)
by re-
movingthe
two
external
retaining
rings
(1)
that
secure
it
to
the
camshaft.
7-14.
Crankshaft
-
With
the
crankshaft
properly
sup-
ported
at
front
and
rear
main
bearings,
remove
the
nuts
securing
the
rod
caps
to
the
connecting
rod.
Re-
move
the
rods
by
tapping
on
the
rod
bolts
with
a soft
hammer.
Discard
the
bearing
inserts,
bolts
and
nuts.
Reassemble
each
cap
with
its
corresponding
rod.
Rods
and
caps
are
not
interchangeable.
7-15.
To
remove
the
crankshaft
gear
(26),
flatten
out
the
lockplate
(24)
and
remove
the
hex
head
screw
(23).
Tap
the
crankshaft
gear
gently,
with
a
fibre
drift,
to
remove
from
the
crankshaft.
Do
not
remove
the
dowel
from
the
rear
end
of
the
crankshaft
unless
it
has
been
obviously
damaged.
Revised
January,
1971
7-1