3208 – Valve Lash Setting

Check and adjust the valve lash with engine stopped.

Valve lash is measured with a thickness gauge between the top of the valve stem and the rocker arm.

NOTE: When the valve lash (clearance) is checked, adjustment is Not Necessary if the measurement is in the range given in the chart for Valve Lash Check: Engine Stopped. If the measurement is outside this range, adjustment is necessary. See the chart for Valve Lash Setting: Engine Stopped, and make the setting to the nominal (desired) specifications in this chart.

To check and make adjustment to the valve lash, use the procedure that follows:

1. Remove the valve covers.


Cylinder, Valve And Pump Location

2. Turn the crankshaft Counterclockwise (as seen from rear of engine) until No. 1 piston is at top center on the compression stroke. The TC-1 mark on the damper assembly will be in alignment with the timing pointer.


Valve Lash Adjustment
(1) Adjustment screw. (2) Locknut. (3) Feeler gauge.

3. Make adjustment to the valves for No. 1 and No. 2 cylinders. To make the adjustment, loosen locknut (2). Turn the adjustment screw (1) until the feeler gauge (3) will go between the end of the valve stem and the rocker arm.

4. After the adjustment is complete, hold adjustment screw (1) and tighten locknut (2) to 32 ± 7 N·m (24 ± 5 lb ft). After the locknut is tightened, check the adjustment again.

5. Turn the crankshaft 180 degrees Counterclockwise (as seen from rear of engine). The VS mark on the damper assembly will be in alignment with the timing pointer. Make adjustment to the valves for No. 3 and No. 7 cylinders.


Tightening Locknut

6. Turn the crankshaft 180 degrees Counterclockwise (as seen from rear of engine). The TC-1 mark on the damper assembly will be in alignment with the timing pointer. Make adjustment to the valves for No. 4 and No. 5 cylinders.

7. Turn the crankshaft 180 degrees Counterclockwise (as seen from rear of engine). The VS mark on damper assembly will be in alignment with the timing pointer. Make adjustment to the valves for No. 6 and No. 8 cylinders.

When the adjustment of the valve lash needs to be done several times in a short period of time, it can be an indication of wear in a different part of the engine. Find the problem and make any necessary repairs to prevent more damage to the engine.

Not enough valve lash, if not corrected, can be the cause of rapid wear of the camshaft and lifters. Not enough valve lash can also be an indication of the seats for the valves being defective. Some reasons for the seats for the valves becoming defective are fuel injection nozzles with defects, restrictions to the inlet air or dirty air filters, wrong fuel setting, or using the engine on loads that are too large for the engine.

Too much valve lash, if not corrected, can be the cause for broken valve stems, push rods, or spring retainers. A fast increase in valve lash can be an indication of any of the following:

a. Camshaft and lifters with wear.
b. Rocker arms with wear.
c. Push rods that are bent.
d. Loose adjustment screw for the valve lash.
e. Broken socket on the upper end of the push rod.
If the camshaft and lifters show signs of rapid wear, look for fuel in the lubrication oil or dirty lubrication oil as a possible cause when making the necessary repairs.

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