G3408C and G3412C Engines Caterpillar

Removal Procedure

Start By:

1. Remove the spark plugs. Refer to Disassembly and Assembly, "Spark Plugs - Remove and Install".

1. Drain the coolant from the cooling system into a suitable container for storage or disposal.

2. Use Tooling (A) to turn the crankshaft and release any pressure on the rocker arms.
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   Illustration 1	g00784581

3. Use Tooling (B) to remove pushrods (1).

4. Remove valve bridges (2).
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   Illustration 2	g01423451

5. Use Tooling (C) and a wrench to remove spark plug adapter (3).
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   Illustration 3	g01423453

6. Remove O-ring seal (4). Remove adapter gasket (5) from the adapter (3).

Installation Procedure

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Illustration 4	g01423453

1. Apply lubricant on O-ring seal (4). Install the O-ring seal on adapter (3). Install adapter gasket (5) .
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   Illustration 5	g01423451

2. Apply Tooling (D) to the threads of spark plug adapter (3). Use Tooling (C) and a wrench to install spark plug adapter (3). Tighten spark plug adapter (3) to a torque of 95 ± 7 N·m (70 ± 5 lb ft).
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   Illustration 6	g00784581

3. Put clean engine oil on the bridge dowels. Install valve bridges (2) in the original positions on the engine. Use the following procedure to adjust the bridges.

   1. Put clean engine oil in the lubrication passage of the bridge.

   2. Back off the adjustment screw. Press straight down on the top contact surface of the bridge with a force of 40 to 60 N (9 to 13 lb).

   3. Turn the adjustment screw clockwise. An oil film in the lubrication passage of the valve bridge will move inward. The oil film indicates that the adjustment screw has made contact with the valve stem.

   4. Turn the screw for an additional 15 to 25 degrees (1/3 flat). This will equalize the clearance with the dowel.

   5. Hold the adjustment screw in this position. Tighten the locknut to a torque of 85 to 115 N·m (65 ± 85 lb ft).

4. Use Tooling (A) to ensure no pressure against pushrod (1) and the rocker arm. Use Tooling (B) to pull rocker arm away from pushrod (1). Put pushrod (1) in position under the rocker arm. If the rocker arm cannot be moved enough to put pushrod (1) in position, turn the crankshaft with Tool (A).

5. Adjust the valves to have a clearance of 0.038 mm (0.0015 inch) for intake and 0.76 mm (0.030 inch) for exhaust. Refer to Testing and Adjusting, "Valve Clearance Setting".

End By:

1. Install the spark plugs. Refer to Disassembly and Assembly, "Spark Plugs - Remove and Install".