I
CYLINDER
HEAD
GASKET
REPLACEMENT
Remove the cylinder heads for lead cleaning and
gasket change at least every200 hours, or when poor
engine performance
is
noticed. For engines running
on unleaded fuel this interval may be extended to400
hours.
1.
2.
3.
4.
5.
6.
Use a 1/2 inch
(13
mm) socket wrench
to
remove
cylinder head bolts. Lift heads
off.
Do
not torque or remove heads
@%!!@I
when they are hot. Warpage
may occur.The gasket surface must be below
100"
F
before removal. At temperatures above
100°F,
the gasket will become gummy and diffi-
cult to remove from the surface
of
the blockand
cylinder head.
After removing heads, clean out all carbon depos-
its. Be careful not to damage the outer sealing
edges where gaskets fit. The heads are made of
aluminum and can be damaged by careless
handling.
Use new head gaskets, and clean both the heads
and the cylinder block thoroughlywhere the head
gaskets rest.
Place a head gasket on the cylinder head, and
align the stud holes in
the
gasket with the stud
holes in the cylinder head. While holding the
gasket against the cylinder head, carefully install
the cylinder head on the engine.
Do
not attempt
to slide the gasket over the studs without the
cylinder head behind
it
or the gasket may tear.
Some engines have two compression washers
and one hardened washer on the long cylinder
head studs (top
6
studs on each side) as shown in
Figure
78.
When these washers are used, they
must be installed as shown. When properly in-
stalled, only the outside edges of the compres-
sion washers
will
be in contact with each other.
Install a flat washer and nut on each of the four
bottom studs.
Follow the head torque sequence shown in Figure
79.
A.
Asbestos head gasket torque procedure:
Tighten all nuts to
5
ft-lbs
(7
Nm), then
10
ft-lb
(14
Nm), then to the torque specified in the
ASSEMBLY
TORQUES
section. Recheck all
nuts for correct torque.
-1
Asbestos gaskets contain
fibers that when airborne
can be harmful to your health. Use a respi-
rator when handling and installing gaskets.
55
B.
Graphoil head gasket torque procedure:
Start outtightening all nutsto5ft-lb(7 Nm),then
10
ft-lb
(14
Nm),
then to the torque specified in
the
ASEMBLY
TORQUES
section. Recheck all
nuts for correct torque.
After the head nuts have been tightened once,
it
will be necessary to tighten each head nut to the
specified torque asecond time. Follow thesame
sequence shown in Figure
79.
Failure to re-
torque could result in a blown head gasket.
.HARDENED
WASHERS
-
HEAD
GASKET
6
LONG STUDSIHEAD
4
SHORT STUDS/HEAD
FIGURE
78.
CYLINDER HEAD WITH
COMPRESSION WASHERS
Too
much torque will flatten the
compression washersand could
result in engine damage.
7.
Recheck torque before engine has run a total of
50
hours.
.
-
-
-
Is
LEFT
CYLINDER
RIGHT
CYLINDER
I
FIGURE
79.
HEAD BOLT TIGHTENING SEQUENCE
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