CUP 2K0621 - Caterpillar

Valve Lash Check
Measure the valve lash between the rocker arm and the valve bridge. Perform checks and adjustments with the engine stopped. The valves must be fully closed. To determine whether the valves are fully closed, refer to Testing and Adjusting, "Finding the Top Center Position for the No. 1 Piston" and Testing and Adjusting, "Crankshaft Position for Valve Lash Setting".An adjustment is NOT NECESSARY if the valve lash is within the tolerance that is listed in Table 1.
Table 1
Valve Lash Check: Engine Stopped
Valves Acceptable Valve Lash Range
Inlet 0.43 mm to 0.58 mm (0.017 inch to 0.023 inch)
Exhaust 1.19 mm to 1.35 mm (0.047 inch to 0.053 inch) If the measurement is not within tolerance, adjust the valve bridge and then adjust the valve lash.Ensuring Proper Valve Lash
Is critical for engine operation that the valve lash is properly set prior to engine start and loading. Misadjusted lash on an engine can result in the engine shutting down shortly after startup, due to false detonation signals from a noisy valve train. To ensure that the lash has been properly set, perform the following procedure:
Set the lash according to Valve Lash Adjustment section.
After the lash has been set, run the engine at 1400 RPM with no load for at least 35 minutes.
Using Cat ET monitor the engine detonation signals. If the detonation level of any cylinder exceeds 50% for any length of time, there may be a lash setting problem.
If any valves do require adjustment, turn off engine and allow the engine to coast to a stop. Wait at least 30 minutes to allow the intake and exhaust valves to cool. Set the lash to the standard values.
Once lash has been adjusted start engine and run at 1400 RPM no load for at least 35 minutes. Check detonation levels to ensure that all detonation levels are below 50%.
If adjusting valve lash did not bring the detonation levels to an appropriate level, then you may have a more serious hardware issue. Visually inspect all valve train components to ensure that there are no visibly damaged parts.Valve Bridge Adjustment
The valve bridge must be adjusted before the valve lash is adjusted. The valve bridge can be adjusted without removing the rocker arms and shafts. The valves must be fully closed. To determine whether the valves are fully closed, refer to Testing and Adjusting, "Finding the Top Center Position for the No. 1 Piston" and Testing and Adjusting, "Crankshaft Position for Valve Lash Setting".Note: If the cylinder head is disassembled, keep the bridges with the respective valves. Check that the bridge dowels are installed to the correct height. Lubricate the bridge dowel, the bore for the bridge dowel, and the top contact surface of the bridge. Install the bridge on the dowel.Use the following procedure to adjust the valve bridges:
Illustration 1 g00662524
(1) Valve cover
(2) Transformer
(3) Ignition harness
Remove valve cover (1).
Disconnect ignition harness (3).
Grasp transformer (2) and pull the transformer straight out of the cylinder head.
Illustration 2 g00808424
(4) Adjusting screw
(5) Locknut
(6) Valve bridge
(7) Rocker arm
Loosen