Cylinder Head and Valves Check and Adjust Valve Assembly Clearances and Injector Preload Rocker arm assembly adjustments consist of intake and exhaust valve clearance (lash) and electronic unit injector preload adjustment. 02 020 4 CAUTION: To prevent accidental starting of engine while performing rocker arm adjustment, ALWAYS disconnect NEGATIVE battery terminal. IMPORTANT: All rocker arm assembly adjustments MUST BE performed with engine COLD. 1. Remove rocker arm cover. (See REMOVE AND INSTALL ROCKER ARM COVER earlier in this group.) RG8228A –UN–05DEC97 2. Remove plug from cylinder block and install JDG820 Flywheel Turning Tool (B). 3.
Remove threaded plug from timing hole below oil cooler and filter housing assembly. JDG971 Timing Pin in Camshaft IMPORTANT: Timing pin MUST BE installed in slot of camshaft first, then install second timing pin in crankshaft slot by carefully rocking flywheel back and forth. RG8227D –UN–05DEC97 4. Rotate engine flywheel in running direction (counterclockwise as viewed from rear) until JDG971 Timing Pin (A) engages single timing slot (D) in camshaft. The proper timing slot can be found by viewing camshaft timing lobe through camshaft timing pin bore while rotating engine.
The double timing slot (E) will be at approximately 11 o’clock (viewed from rear of engine) when pin is installed in slot (D).This ensures that engine is locked at TDC of No. 1 cylinder’s compression stroke. Intake and exhaust rocker arms on No. 1 cylinder should be loose. JDG971 Timing Pin in Crankshaft A—JDG971 Timing Pin B—JDG820 Flywheel Turning Tool C—JDG971 Timing Pin D—Single Timing Slot E—Double Timing Slot RG11165 –UN–30OCT00 Camshaft Timing Slot CTM100 (06APR04) 02-020-4 P OWER T ECH 10.5 L & 12.5 L Diesel Engines Continued on next page RG,RG34710,63 –19–16OCT00–1/6 040604 PN=76