an outside diameter of approximately
4. Remove the fuel injectors.
0.953". Replace this spring when a load
5. Remove the exhaust valve bridges.
of less than 25 pounds (111 N) will com-
press it to 1.80" (installed length).
6. Place a block of wood under the cylin-
der head to support the exhaust valves.
Inspect the valve spring seats and caps
for
wear.
If
worn,
replace
with
new
7. Thread the valve spring compressor
parts.
adaptor J 7455-1 into one of the rocker
arm bracket bolt holes in the cylinder
Examine the contact surfaces of the ex-
head (see Figure 11B-51). Then com-
haust valve bridge, guides, bridges and
press the valve spring and remove the
adjusting screws for wear or galling.
t w o piece tapered valve lock.
Replace excessively worn parts.
8. Release the tool and remove the valve
Carbon on the face of a valve could indi-
c a t e b l o w - b y d u e t o a f a u l t seat. Black
spring cap, valve spring and spring
seat.
carbon deposits extending from the valve
s e a t s to the valve guides may result from
9. Turn the cylinder head over, using
cold operation due to light loads or the
care to keep the valves from falling out
use of too heavy a grade of fuel. Rusty
of the head. If the valves are to be re-
brown valve heads with carbon deposits
used, number each valve to facilitate re-
forming n a r r o w c o l l a r s n e a r t h e v a l v e
installation in the same location. Then
guides is evidence of high operating
withdraw the valves from the cylinder
temperatures. High operating temper-
head.
atures are normally due to overloads,
inadequate cooling or improper timing
10. Remove the cam followers and push
which results in carbonization of the lu-
rod assemblies as outlined under Remove
bricating oil.
Cam Follower and Push Rod Assembly
(Cylinder Head Removed from Engine).
Clean the carbon from the valve stems
and wash the valves with fuel oil. The
valve stems must be free from scratches
Inspection
or scuff marks and the valve faces must
be free from ridges, cracks or pitting.
Clean the springs with fuel oil, dry them
If necessary, reface the valves or install
with compressed air and inspect them.
new valves. If the valve heads are
Replace a pitted or fractured spring.
warped, replace the valves.
U s e spring tester J 22738-02 to check the
If there is evidence of engine oil running
spring load (see Figure 11B-52 on page
down the exhaust valve stem into the ex-
11B-36). The exhaust valve spring has
haust chamber, creating a high oil con-
sumption condition because of excessive
idling and resultant low engine exhaust
back pressure, replace the valve guide
oil seals or, if not previously used, in-
s t a l l valve guide oil seals.
Clean the inside diameter of the valve
guides with brush J 5437 (see
Figure
11B-53
on
page
11B-36).
This
brush will remove all gum or carbon de-
posits from the valve guides, including
the spiral grooves.
Inspect the valve guides for fractures,
chipping, scoring or excessive wear.
Measure the valve guide inside diameter
with a pin gauge or inside micrometer
and record the readings. After inspect-
ing and cleaning the exhaust valves,
m e a s u r e the outside diameter of the valve
stems with a micrometer and record the
F i g u r e 11B-51. Removing Exhaust
readings. Compare the readings to ob-
V a l v e Spring
E n g i n e (Less Major Assemblies)
