Air Inlet and Exhaust System 70 UENR0623-02 2. Check the rocker arms for an engine valve lash. There should be no engine valve lash. 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. Illustration 60 g02948536 Typical example Too much valve lash can be an indication of the following problems: 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. 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 4. Use Tooling (A) to rotate the crankshaft in a clockwise direction.
The crankshaft should be rotated 360 degrees. If the camshaft and valve lifters show rapid wear, look for fuel in the lubrication oil or dirty lubrication oil as a possible cause. 5. Check the rocker arms for an engine valve lash. There should be no engine valve lash. Valve Lash Check 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. 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.