TM 5-3895-346-14
ENGINE OVERHAUL
EXHAUST VALVES
3. Remove the two bolts holding the rocker arm shaft brackets to the cylinder head. Then remove the
brackets and the shaft.
4. Remove the fuel injectors.
5. Place a block of wood under the cylinder head to support the exhaust valves. Remove the exhaust valve
springs as outlined in steps 6 and 7 above.
6. Turn the cylinder head over, using care to keep the valves from falling out of the head. If the valves are
to be reused, number each valve to facilitate reinstallation in the same location. Then withdraw the valves
from the cylinder head.
7. Remove the cam followers and push rod assemblies as outlined in Valve Operating Mechanism under
Remove Cam Follower and Push Rod Assembly (Cylinder Head Removed from Engine).
Inspection
Clean the springs with fuel oil, dry them with compressed air, and inspect them. Replace a pitted or fractured
spring.
Use spring tester J 22738-02 to check the spring load (Fig. 3). Replace a spring if a load of less than 33
pounds will compress a two-valve cylinder head spring to 2.31 inches, or a load of less than 25 pounds will
compress a four-valve cylinder head spring to 1.93 inches. The difference in the load between a pair of four-
valve cylinder head springs must not exceed 6 pounds or the valve bridge will be unbalanced.
To eliminate exhaust valve spring surge, a new valve spring (0.148-inch wire diameter) is used in the in-line 4-
53 engine. The change is effective with approximate engine serial numbers 4D-112278 and 6D-82217. The
former spring was made from 0.135-inch diameter wire.
Figure 3. Testing Valve Spring Using Tool J 22738-02
The new spring can be used only in engines built after serial numbers 4D-112278 and 6D-60776 and use the
present low-lift camshaft, or older engines which have these low-lift camshafts installed.
CAUTION
The use of the new spring with the former high-lift camshaft (O.327-inch valve
cam lobe lift, metal stamped V7 or V at both ends) will cause the valve springs to
bottom out, resulting in bent push rods and possible engine damage.
NOTE
The low-lift camshaft which provides a maximum valve cam lobe lift of 0.276-inch
is metal stamped V7L at both ends.
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