User Manual

Illustration 59 g01353215
Cylinder and valve location
(A) Inlet valve
(B) Exhaust valve
Too much valve lash can cause some broken valve
stems, springs, and spring retainers. Damage to the
valve mechanism will produce emissions in excess of
the correct specification.
The hydraulic lifter will compensate for all normal
wear of the components of the valve train.
Too much valve lash can be an indication of the
following problems:
• Worn camshaft and valve lifters
• Worn rocker arms
• Bent pushrods
• Broken socket on the upper end of a pushrod
• Loose adjustment screw for the valve lash
• Issues with the hydraulic lash adjusters
If the camshaft and valve lifters show rapid wear, look
for fuel in the lubrication oil or dirty lubrication oil as a
possible cause.
Valve Lash Check
Accidental engine starting can cause injury or
death to personnel.
To prevent accidental engine starting, turn the
ignition switch to the OFF position and place a do
not operate tag at the ignition switch location.
1. Find top center position for number one piston.
Refer to Systems Operation, Testing and
Adjusting, “Finding Top Center Position for No. 1
Piston” for the correct procedure.
2. Check the rocker arms for an engine valve lash.
There should be no engine valve lash.
Illustration 60 g02948536
Typical example
3. If there is an engine valve lash at any position the
engine valve lash may be caused by a normal
leakdown of the hydraulic lash adjuster. Push the
affected rocker arm (1) against the pushrod. The
rocker arm (1) should rotate as the pushrod is
pushed up by the recovery of the hydraulic lifter.
Once all motion has ceased test again for an
engine valve lash. There should be no engine
valve lash.
4. Use Tooling (A) to rotate the crankshaft in a
clockwise direction. The crankshaft should be
rotated 360 degrees.
5. Check the rocker arms for an engine valve lash.
There should be no engine valve lash.
6. If there is an engine valve lash at any position the
engine valve lash may be caused by a normal
leakdown of the hydraulic lash adjuster. Push the
affected rocker arm (1) against the pushrod.
Monitor the rocker arm (1) for movement. The
rocker arm (1) should rotate as the pushrod is
pushed up by the recovery of the hydraulic lash
adjuster. Once all motion has ceased test again for
an engine valve lash. There should be no engine
valve lash.
70 UENR0623-02
Air Inlet and Exhaust System
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