Caterpillar 3406 — Adjust Engine Valve Lash

Adjustments

For the Caterpillar 3406, from the Caterpillar operator's manual.

Applies to: Caterpillar 3406

Procedure

1. Adjust valves with the engine stopped and cold.
2. Remove the flywheel housing timing hole cover.
3. Remove the plug.
4. Rotate the flywheel in direction of engine rotation until timing bolt can be installed in flywheel.
5. Install the timing bolt in the flywheel. This is the top bolt of the two bolts that secure the flywheel housing cover.
6. Determine if No. 1 piston is on compression or exhaust stroke. The cylinder on compression will have both inlet and exhaust valves closed. If valves are open, rotate engine 360° to obtain TDC No. 1 co
7. With No. 1 piston at TDC on compression, check lash between the bridge and rocker arm on exhaust valves of cylinders 1, 3 and 5, and inlet valves for cylinders 1, 2 and 4.
8. To adjust, loosen valve adjusting lock nut and turn adjusting screw to allow proper size feeler gauge to pass between top of bridge and the valve rocker arm.
9. Set lash at .015 (0.38 mm) for inlet valves and .030 (0.76 mm) for exhaust valves.
10. Tighten adjusting screw locknut and check lash.
11. Turn flywheel 360° in direction of engine rotation. Align flywheel timing bolt with the timing hole in the flywheel. No. 6 cylinder will be at TDC compression stroke.
12. Check lash between the bridge and rocker arm on exhaust valves for cylinders 2, 4 and 6, and inlet valves for cylinders 3, 5 and 6. Adjust valves if necessary.

Full service-parts list: Caterpillar 3406 →

Source: Caterpillar operator's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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