G3306B Petroleum Generator Set Engines Caterpillar

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To prevent possible injury, do not use the starter to turn the flywheel. Hot engine components can cause burns. Allow additional time for the engine to cool before measuring valve clearance.

Note: Valve lash is measured at the top of wear seat for the intake valves and the exhaust valves. All of the clearance measurements and the adjustments must be made with the engine stopped. Ensure that the valves are fully closed.

Valve Lash Check

An adjustment is not necessary if the measurement of the valve lash is in the acceptable range. Adjust the valve lash while the engine is stopped. The range is specified in Table 2.

If the measurement is not within this range, adjustment is necessary.

Illustration 1	g01943583
Location of the valve components (right side engine view) (A) Adjuster assembly for the inlet valve (B) Adjuster assembly for the exhaust valve (C) The wear seat for the rocker arms

Valve Lash Adjustment

Illustration 2	g01943695
Installation of the 1U-8869 Dial Indicator (1) Adjuster assemblies (2) 1U-8869 Dial Indicator

Adjust the valve lash while the engine is stopped.

1. Put the No. 1 piston at the top center position on the compression stroke. Refer to Testing and Adjusting, "Finding Top Center Position for No. 1 Piston".
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   Table 4

   TC Compression Stroke (1)	Inlet Valves	Exhaust Valves
   Cylinders	1-2-4	1-3-5

2. Install the 1U-8869 Dial Indicator onto the appropriate arm assembly:

   1. Perform the valve adjustment for each of the valves that are listed in the Table above that is specific to your engine family.

   2. Attach the magnetic base for the dial indicator to a machined surface on the engine. Ensure that the base is securely fastened to the surface.

   3. Adjust the holding rods so that the dial indicator probe is located on the flat portion of the top of the rocker arm wear seat.

      Refer to Illustration 2.

3. Lightly tap the rocker arm at the top of the adjustment screw with a soft mallet. This procedure will ensure that the lifter roller seats against the base circle of the camshaft lobe.

4. Zero the dial indicator.

5. Pivot the rocker arm on the rocker shaft. The valve lash is the total movement that is indicated by the dial indicator as the rocker arm pivots on the rocker shaft.

6. Adjust the valve lash according to Table 3.

   1. Loosen the adjustment locknut.

   2. Turn the adjuster in order to obtain the appropriate reading for the valve lash that is measured on the dial indicator.

   3. Tighten the adjustment locknut to a torque of 30 ± 7 N·m (22 ± 5 lb ft). Do not allow the adjustment screw to turn while you are tightening the adjustment locknut. Recheck the valve lash after tightening the adjustment locknut.

7. Repeat these test steps for each of the valves that are listed in Table 4.

8. Remove the timing bolt and turn the flywheel by 360 degrees in the direction of engine rotation. The No. 6 piston will be at the top center position on the compression stroke. Install the timing bolt in the flywheel.
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   Table 5

   TC Exhaust Stroke (2)	Inlet Valves	Exhaust Valves
   Cylinders	3-5-6	2-4-6
   Valve lash	0.38 ± 0.08 mm (0.015 ± 0.003 inch)	0.75 ± 0.08 mm (0.030 ± 0.003 inch)

9. Repeat steps 2 through 6 for each of the valves that are listed in the Table above.

10. Remove the timing bolt from the flywheel after all adjustments to the valve lash have been made. Reinstall the timing cover.