3406E and 3456 Engine Valve Lash Adjustment

Valve Lash Check

An adjustment is not necessary if the measurement of the valve lash or clearance is in the acceptable range in Table 1.

If the measurement is not within this range, an adjustment is necessary. Refer to “Valve Lash Adjustment” for the proper procedure.

Finding Top Center Position for No. 1 Piston

The No. 1 piston at top center (TC) on the compression stroke is the starting point of all timing procedures.

Note: Some engines have two threaded holes in the flywheel. These holes are in alignment with the holes with plugs in the left and right front of the flywheel housing. The two holes in the flywheel are at a different distance from the center of the flywheel. This distance ensures that the timing bolt cannot be put in the wrong hole.

1. Timing bolt (1) is a cover bolt. The timing bolt can be installed in either the left side of the engine at location (2) or in the right side at location (4) . Remove both bolts (1) and cover (3) from the flywheel housing. Remove the plug from the timing hole in the flywheel housing.

2. For the left side of the engine, put timing bolt (1) (longer bolt) through the timing hole in the flywheel housing. Tooling (A) and a 1/2 inch drive ratchet wrench are used in order to turn the engine flywheel in the direction of normal engine rotation. Normal engine rotation is counterclockwise. Normal engine rotation is viewed from the flywheel end of the engine. Turn the engine flywheel until the timing bolt engages with the threaded hole in the flywheel.

3. For the right side of the engine, put timing bolt (1) (longer bolt) through the timing hole in the flywheel housing. Tooling (B) , tooling (C) , and a 1/2 inch drive ratchet wrench are used to turn the flywheel in the direction of normal engine rotation. Normal engine rotation is counterclockwise. Normal engine rotation is viewed from the flywheel end of the engine. Turn the engine flywheel until the timing bolt engages with the threaded hole in the flywheel.

Note: If the flywheel is turned beyond the point of engagement, the flywheel must be turned in the opposite direction approximately 45 degrees. Then turn the flywheel in the direction of normal rotation until the timing bolt engages with the threaded hole. The procedure will eliminate the backlash that will occur when the No. 1 piston is put on the top center.

4. Remove the front valve mechanism cover from the engine.

5. The inlet and exhaust valves for the No. 1 cylinder are fully closed if the No. 1 piston is on the compression stroke. Also, the rocker arms can be moved by hand when the No. 1 piston is on the compression stroke. If the rocker arms cannot be moved and the valves are slightly open, the No. 1 piston is on the exhaust stroke.

Note: After the actual stroke position is identified, and the other stroke position is needed, remove the timing bolt from the flywheel. The flywheel is turned 360 degrees in a counterclockwise direction. The timing bolt is reinstalled.

Valve Lash Adjustment Sequence

Illustration 1 g01373511
Cylinder and valve location
(A) Exhaust valves
(B) Inlet valves

Use the following procedure to adjust the valve clearance:

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”.
   

   Table 2

   TC Compression Stroke	Inlet Valves	Exhaust Valves
   Valve Lash	0.38 ± 0.08 mm (0.015 ± 0.003 inch)	0.76 ± 0.08 mm (0.030 ± 0.003 inch)
   Cylinders	1-2-4	1-3-5

2. Adjust the valve clearance according to Table 2.
   1. Lightly tap the rocker arm with a soft mallet. This action will ensure that the lifter roller seats against the base circle of the camshaft.

    

   2. Loosen the adjustment locknut.

    

   3. Place the appropriate feeler gauge between rocker arm and the valve bridge. Then, turn the adjustment screw in a clockwise direction. Slide the feeler gauge between the rocker arm and the valve bridge. Continue turning the adjustment screw until a slight drag is felt on the feeler gauge. Remove the feeler gauge.

    

   4. 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.

3. Remove the timing bolt and turn the flywheel by 360 degrees in the direction of engine rotation. This action will put the No. 6 piston at the top center position on the compression stroke. Install the timing bolt in the flywheel.
   

   Table 3

   TC Exhaust Stroke	Inlet Valves	Exhaust Valves
   Valve Lash	0.38 ± 0.08 mm (0.015 ± 0.003 inch)	0.76 ± 0.08 mm (0.030 ± 0.003 inch)
   Cylinders	3-5-6	2-4-6

4. Adjust the valve lash according to Table 3.
   1. Lightly tap the rocker arm with a soft mallet. This action will ensure that the lifter roller seats against the base circle of the camshaft.

    

   2. Loosen the adjustment locknut.

    

   3. Place the appropriate feeler gauge between rocker arm and the valve bridge. Then, turn the adjustment screw in a clockwise direction. Slide the feeler gauge between the rocker arm and the valve bridge. Continue turning the adjustment screw until a slight drag is felt on the feeler gauge. Remove the feeler gauge.

    

   4. 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.

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

Refer to Testing and Adjusting, “Electronic Unit Injector – Adjust”.

Here’s a DIY video how to sequentially adjust cat 3406e valve clearance. In this video you can find short explanation of checking and adjusting the valves clearance and injectors on an electronic cat engine.