CASE AS 7T9133 - Caterpillar

Ignition systems can cause electrical shocks. Avoid contacting the ignition system components and wiring.Do not attempt to remove the valve covers when the engine is operating. The transformers are grounded to the valve covers. Personal injury or death may result and the ignition system will be damaged if the valve covers are removed during engine operation. The engine will not operate without the valve covers.
For procedures on adjusting the valve bridge and the engine valve lash, refer to the following publications:
Special Instruction, REHS0128, "Using the 147-5482 Indicator Gauge for Valve Lash and Valve Bridge Adjustment"
The Systems Operation/Testing and Adjusting manual for the engine
The Specifications manual for the engineConsult your Caterpillar dealer for assistance.Valve Bridge
Check the valve bridge and adjust the valve bridge, if necessary. Perform the procedure for both valve bridges for each cylinder.After the valve bridge for each cylinder is satisfactory, measure the valve lash.Engine Valve Lash
Only qualified service personnel should perform this maintenance. Refer to the Service Manual or your Caterpillar dealer for the complete valve lash adjustment procedure.Operation of Caterpillar engines with improper valve adjustments can reduce engine efficiency. This reduced efficiency could result in excessive fuel usage and/or shortened engine component life. Improper valve lash may also lead to valve failure, and result in catastrophic failure.
If the valve lash is within the tolerance, an adjustment of the valve lash is NOT necessary.Perform valve lash adjustment if the dimension is not within the tolerance. The valve bridge adjustment must be performed before making a valve lash adjustment.Perform the valve lash setting when the engine is cold. After the engine has been shut down and the valve covers are removed, the engine is considered cold.Before performing maintenance, prevent the entry of foreign matter into the top of the cylinder head and the valve mechanism. Thoroughly clean the area around the valve mechanism covers.For further information, refer to Systems Operation Test and Adjust, "Valve Lash and Valve Bridge Adjustment".