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SECTION 10
INSPECTION AND RECONDITIONING
Valve Guides
If a valve guide is wom beyond specifications, it will
not guide the valve in a straight line. This may result
in burnt valve faces or seats, loss of compression,
and excessive oil consumption.
To check valve guide to valve stem clearance, thor-
oughly clean the valve guide and, using a split-ball
gauge, measure the inside diameter. Then, using an
outside micrometer, measure the diameter of the valve
stem at several points on the stem where it moves in
the valve guide. Use the largest stem diameter to cal-
culate the clearance. If the clearance exceeds .005"
on intake or .007" on exhaust valve, determine wheth-
er the valve stem or the guide Is responsible for the
excessive clearance.
If the valve stem diameter is within specifications, then
replace the valve guide.
Remove Valve Gulde
The valve guides are a tight press fit in the cylinder
barrel. A valve guide removal tool is recommended to
remove the guides (refer to Section 2, "Special
Tools"). To remove valve guide, refer to Figure 10-6
and proceed as follows:
Adapter
Cylinder
Stud--5/16" x 2-1/2"
Figure 10-6. Pulling Valve Guide.
. Install 5/16-18 NC nut on coarse threaded end of
2-1/2" long stud.
2. Insert other end of stud through valve guide bore
and install 5/16-24 NF nut. Tighten both nuts
securely.
NOTE:
Valve guide must be held firmly by the
stud assembly so that all slide hammer
force will act on the guide.
3. Assemble the valve guide removal adapter to the
stud and then the slide hammer to the adapter.
4. Use the slide hammer to pull the guide out.
Install Valve Guide
To install valve guide, proceed as follows:
1. Make sure valve guide bore is clean and free of
nicks or bums.
2. Using valve guide driver (Refer to Section 2,
"Special Tools"), align and then press guide in
until valve guide driver bottoms on depth gauge.
See Figure 10-7.
Driver
(Tool #11763)
Depth Gauge
(Tool #11770-tor M18
A
#11771-for M20)
Cylinder
Barrel
Figure 10-7.
Installing Valve Guide.
3. Valve guides are often slightly cornpressed during
insertion. Use a piloted reamer (Refer to
Section 2, "Special Tools") and then a finishing
reamer to resize the guide bore to .3125". Refer
to Figure 10-8.
10.7
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