274 6 PERFORMANCE DIAGNOSTICS
18. Valv e Lash and Bra ke Lash
Figure 355
NOTE: If Tests 1-17 meet specifications, engine
operation is good: Test 18 is not necessary.
Figure 356
Purpose
• To check or adjust valve lash for intake and
exhaust valves
• To check or adjust actuator lash for Diamond
Logic® engine brake
Tools
• Feeler gauge
• Straight-blade screwdriver
• Open end wrench (two sizes)
• Torque wrenc h
• Crows foot (two sizes)
WARNING: To avoid serious personal injury,
possible death or damage to the engine or
vehicle, read all safety instructions in the “Safety
Information” section of this manual.
Valve Lash for Intake and Exhaust Valves
During the procedure to adjust valve lash, the
crankshaft is rotated two times:
• Six valve adjustments are made when piston 1 is
at Top Dead Center (TDC) compression.
• Six valve adjustments are made when piston 6 is
at Top Dead Center (TDC) compression.
If the engine is equipped with the Diamond Logic®
engine brake, corresponding brake actuator lash can
be adjusted before rotating the crankshaft the second
time.
Adjusting Valve Lash
1. Remove valve cover following procedure in
Engine Service Manual.
2. Turn crankshaft in the direction of engine rotation
to remove gear lash from gear train and align the
timing mark on the damper pulley with the TDC
mark on the front cover.
3. Co nfirm that piston 1 is at TDC compression
by turning both push rods by hand to v erify that
valves are closed.
• If push rods a re loose and turn easily, piston 1
is at TDC compression and valves are closed.
If piston 1 is at TDC compression, see and do
steps 4, 5, and 6.
• If push rods will not turn easily for cylinder 1,
piston 6 is at TDC compression. Confirm that
valves are closed by making sure that push
rods for cylinder 6 are loose and turn easily. If
piston 6 is at TDC compression, see and do
steps 4, 5, and 6.
EGES-270-1
Read all safety instructions in the "Safety Information" section of this manual before doing any proced ures.
Follow all warnings, cautions, and notes.
©August 2008 Navistar, Inc.
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