SHOP MANUAL
Paragraphs 35-39
PISTON AND RINGS
All Models
35.
Three -rin g,
cam
ground
aluminum pistons
are
used
on all
models. Pistons
and
rings
are
available
in standard size and 0.5 mm (0.020 inch)
oversize.
Piston ring
end gap
should
be
0.30-0.45 mm (0.012-0.018 inch) for com-
pression rings
and
0.25-0.40
mm
(0.010-0.016 inch)
for oil
control ring.
Maximum allowable
end gap for any
ring
is 1.25
mm (0.049 inch). Top com-
pression ring
is
half-keystone type
as
shown
in
Fig.
53 and
side clearance
is
not measured. Second compression ring
should have
a
side clearance of 0.09-0.12
mm (0.004-0.005 inch).
Oil
control ring
side clearance should
be
0.02-0.05
mm
(0.001-0.002 inch).
When installing rings onto piston,
be
sure manufacturer's name
or "TOP"
mark
on
ring
is
towards
top of
piston.
Make certain notched outer edge on se-
cond compression ring (Fig. 53) is facing
down. Position coil expander joint on op-
posite side
of
oil control ring gap. Stag-
ger rings
on
piston
so end
gaps
are 90
degrees apart with
no
gap aligned with
piston pin.
PISTON PINS
All Models
36.
The
full fioating piston
pin is a
transition
fit in
piston bosses
at
room
temperature. Heat piston prior
to
reassembly
to
ease piston
pin
installa-
tion. Piston pins
are
available
in
stan-
dard size only.
Inside diameter
of
pin bore
in
piston
should
be
23.000-23.013
mm
(0.9055-
0.9060 inch)
and
maximum usable bore
diameter
is
23.053
mm
(0.9076 inch).
Piston
pin
diameter should
be
23.002-23.011 mm (0.9056-0.9059 inch).
Pin should have
an
operating clearance
of 0.014-0.038 mm (0.0006-0.0015 inch)
in connecting
rod
bushing. Maximum
allowable clearance
is 0.15 mm
(0.006
inch).
CYLINDER SLEEVES
All Models
37.
Cylinder sleeves used
in all
models are dry-type sleeves which are
a
tight press
fit in
cylinder block. Sleeves
which
are
worn beyond
the
allowable
Hmit
of 0.15 mm
(0.006 inch)
may be
bored and honed to accept O.f) mm (0.020
inch) oversize pistons
and
rings. When
oversized sleeve
is
worn beyond
allowable limit, sleeve must be renewed.
New sleeve should be pressed into block
bore until flush with
top of
block. New
sleeves
are
semi-finished
and
must
be
bored
and
honed
to
obtain desired
clearance
of
0.075-0.100
mm
(0.003-0.004 inch)
for
piston skirt. Stan-
dard finished diameter
of
sleeve
is as
follows:
On
Models L185, L235, L245,
L285 and L345, diameter
is
76.00-76.02
mm (2.992-2.993 inches).
On
Models
L275,
L295, L305 and L855, diameter is
82.00-82.02 mm (3.228-3.229 inches).
CONNECTING RODS
AND BEARINGS
All Models
38.
Connecting rod bearings are slip-
in, precision type, renewable from below
after removing
oil pan and
connecting
rod
cap.
When installing connecting
rods,
make certain match marks on cap
and
rod are
aligned (Fig. 53)
and
face
AWAY from camshaft side
of
engine.
Connecting rod bolt torque is
37-41
N*m
(27-30 ft.-lbs.) with threads oiled.
Standard crankpin diameter
is
43.959-43.975
mm
(1.7307-1.7313
in-
ches)
for all
models. Desired operating
clearance between crankpins
and
bear-
ings
is
0.035-0.093
mm
(0.0014-0.0037
inch) and maximum allowable clearance
is 0.20 mm (0.008 inch). Connecting rod
bearings
are
available
in
standard size
and also 0.20 mm (0.008 inch) and
0.40
mm (0.016 inch) undersizes.
CRANKSHAFT AND
MAIN BEARINGS
All Models
39.
On all
models crankshaft
and
main bearing assemblies
are
removed
from rear
of
engine
as
follows: Remove
engine assembly, then remove
rod and
piston units, timing gear cover,
crankshaft gear, flywheel and rear bear-
ing cover. Remove l)earing case retain-
ing cap screws (20-F'ig. 54), then bump
crankshaft and bearings rearward out of
cylinder block. Note that bearing cases
are minimum clearance in cylinder block
bores
to
provide
oil
pressure transfer
through drillings
in
bearing cases.
Front main bearin|j^ (2)
is a
one-piece
bushing type, presse(i into front face of
cylinder block. Remainder
of
main bear-
ings are two-piece bushing type contain-
ed
in
two-piece bearing cases
(21).
Crankshaft
end
piay
is
controlled
by
thrust washers (25) located on rear main
bearing.
Standard main journal diameter
is
51.921-51.940
mm
(2.044-2.045 inches)
Desired diametral clearance
in
front
main bearing
is
0.040-0.118
mm
(0.0016-0.0046 inch) and in remainder of
bearings
is
0.040-0.104
mm
(0.0016-0.0041 inch). Maximum
allowable clearance for all main bearings
is
0.20 mm
(0.008 inch). Bearings
are
available
in
standard size as well as 0.20
mm (0.008 inch)
and 0.40 mm
(0.016
inch) undersizes.
Crankshaft
end
play should
be
0.15-0.30
mm
(0.006-0.0^12 inch) with
and allowable limit
of 0.5 mm
(0.020
inch).
Thrust washers (25-Fig. 54)
are
available
in
standard size
and
also 0.20
mm (0.008 inch)
and 0.40 mm
(0.016
inch) oversizes. When reinstalling thrust
washers,
be
sure
oil
grooves
are
facing
outward.
Reinstall crankshaft
by
reversing
the
removal procedure while noting follow-
ing items: Assemble bearing cases star-
ting with smallest outside diameter case
at front
of
crankshaft. Be sure
to
align
bearing case match marks. Tighten
bearing case
cap
screws
to a
torque
of
30-34
N-m
(22-25 ft.-lhs.)
and
case
Fig. 54—Expioded view of
crankshaft, main bearings.
connecting rod and piston of
the type used on aii models.
Some
models do not use
iock plates (8 and 11).
1.
2.
:].
4.
5
6.
7.
H.
!>.
10.
11.
12.
\'A.
14.
H;.
17.
IH.
\u.
20.
21.
22.
23
24.
25.
Oatikshaft
Main hearing (front)
f'itot hearing
Gasket
Gasket
Bearing cover
Seal
Lock plate
Flywheel
Lock plate
L(K'k plate
Rearing insert
Connecting
rod
Hushing
Snap ring
I'iston
pin
Piston
Oil control
HnK
Compression rings
Locating cap screw
Main hearing case
Lock plate
or
washer
Cap screw
Main hearing insert
Thrust washers
25
23
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