Engine Valve Lash - Inspect/Adjust SMCS - 1102-025 Be sure the engine cannot be started while this maintenance is being performed. To prevent possible injury, do not use the starting motor to turn the flywheel. Hot engine components can cause burns. Allow additional time for the engine to cool before measuring/adjusting engine valve lash clearance. The valve lash is measured between the top of the cap of the valve stem and the rocker arm. The valve lash is measured with a feeler gauge. Valve Lash Setting with Stopped Engine (Cold) Inlet and Exhaust Valve ... 0.25 mm (0.010 inch) Use the following procedure to check and make adjustments to the valve lash: 1. Remove the valve covers. 2. Turn the crankshaft in a counterclockwise direction until the No. 1 piston is at the top center on the compression stroke. The rotation of the crankshaft is viewed from the rear of the engine. The alignment mark on the pulley assembly will be in alignment with the timing pointer. Note: The crankshaft may be turned by using a socket wrench on the bolt in the crankshaft pulley. The crankshaft may also be turned by turning the alternator. This will turn the belt and this will turn the crankshaft pulley. Note: Refer to the Engine Supplement, Disassembly and Assembly for your specific machine for additional information. 3. 3064 Engine: Adjust the valve lash on the inlet valves for cylinders 1 and 2. Adjust the valve lash on the exhaust valves for cylinders 1 and 3. 3066 Engine: Adjust the valve lash on the inlet valves for cylinders 1, 2, and 4. Adjust the valve lash on the exhaust valves for cylinders 1, 3, and 5. 4. Turn the flywheel for 360 degrees in the direction of engine rotation. The No. 4 piston (four cylinder) and the No. 6 piston (six cylinder) will be at the top center (TC) on the compression stroke. 5. 3064 Engine: Adjust the valve lash on the inlet valves for cylinders 3 and 4. Adjust the valve lash on the exhaust valves for cylinders 2 and 4. 3066 Engine: Adjust the valve lash on the inlet valves for cylinders 3, 5, and 6. Adjust the valve lash on the exhaust valves for cylinders 2, 4, and 6. 6. Hold the adjustment screw and tighten the locknut after the adjustment is complete. Adjusting the valve lash several times in a short period indicates wear in a different part of the engine. Find the problem and make any necessary repairs in order to prevent more damage to the engine. Rapid wear of the camshaft and tappets can occur if insufficient valve lash is not corrected. Insufficient valve lash can also be an indication of faulty valve seats. The following items are reasons for faulty seats of the valves: faulty fuel injection nozzles, restrictions to the air inlet, dirty air filters, incorrect fuel setting and overloading the engine. Broken valve stems, broken pushrods, or broken spring retainers can be caused by insufficient valve lash that is not corrected. A fast increase in valve lash can be an indication of any of the following items: Worn camshaft and tappets Worn rocker arms Bent pushrods Loose adjustment screws for valve lash Broken socket on the upper end of pushrod Fuel in the lubrication oil may be a possible cause of rapid wear of the camshaft and the tappets. Dirty lubrication oil may also be a possible cause of rapid wear of
