3512C Engine Caterpillar

Removal Procedure

Start By:

1. Remove the valve mechanism cover.

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Illustration 1	g01119693

1. Remove bolts (1). Remove rocker shaft assembly (2) from valve mechanism cover base (6). Remove valve pushrods (4).

   Note: Mark the valve pushrods for identification of location for assembly.

2. Remove bridge assemblies (3) from the valve stems.

   Note: Mark the bridge assemblies with identification of location for assembly.

3. To remove pushrod (5), it is necessary to remove valve mechanism cover base (6).

Installation Procedure

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Illustration 2	g01119759

1. Loosen jam nut (8) and adjustment screw (7). Loosen jam nut (10) and adjustment screw (9).
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   Illustration 3	g01131377

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   Illustration 4	g01158612
   Valve bridge for dowel installations

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   Illustration 5	g01946786
   Floating valve bridge (X) Round pocket (Y) Slotted pocket (Z) Outside of engine

2. Apply clean engine oil to pushrod (5).

3. Apply clean engine oil to valve pushrods (4), and the cup of the valve lifters. Install valve pushrods (4) in the original location.

4. Valve bridge assemblies for dowel installations have an adjustment screw and a jam nut. Use the following procedure to install this configuration.

   1. Loosen adjustment screw (11) and jam nut (12) on bridge assembly (3).

   2. Coat these items with clean engine oil: the dowels, the receptacle of the bridge assembly for the dowels and the uppermost contact surface of bridge assembly (3).

   3. Place bridge assembly (3) into position on the dowel. Apply a downward force of 5 to 45 N (1 to 10 lb) on the uppermost contact surface of bridge assembly (3). While you apply the force, turn adjustment screw (11) until the adjustment screw contacts the valve stem.

   4. Turn the adjustment screw for an additional 20 to 30 degrees (1/3 to 1/2 of the hex).

   5. Hold the adjustment screw in position and tighten jam nut (12) to a torque of 30 ± 4 N·m (22 ± 3 lb ft).

5. For floating valve bridge assemblies, use the following procedure.

   1. Apply clean engine oil to the contact surface of bridge assemblies (3) and the valve stems. Install bridge assemblies (3) on the valve stems.

   2. Install the bridge assemblies with the round pocket toward the outside of the engine. Refer to Illustration 5.
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   NOTICE
   Ensure that the crankshaft and the camshafts are in time with each other. Also ensure that the adjustment screws in the rocker arms are loosened completely before the bolts on the rocker shaft are tightened or damage to the valves and the pistons may occur.

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   NOTICE
   If the rocker shaft is not positioned correctly, the oil supply to the sleeve bearings in the rocker arm will be shut off. This will cause seizure of the bearings and severe damage to the engine. Be sure to orient the rocker shaft in the correct position.

6. Place rocker shaft assembly (2) in position on valve mechanism cover base (6). Make sure that valve pushrods (4) and pushrod (5) are aligned with the rocker arms. Install bolts (1). Tighten the bolts to a torque of 215 ± 40 N·m (160 ± 30 lb ft).
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   Illustration 6	g01119849

7. Adjust the valve lash according to Testing and Adjusting, "Valve Lash and Valve Bridge Adjustment". Hold adjustment screw (7) of the rocker arm assembly and tighten jam nut (8) to a torque of 70 ± 15 N·m (52 ± 11 lb ft).

8. Adjust the electronic unit injector lash according to Testing and Adjusting, "Fuel Injector Adjustment". Hold adjustment screw (9) of the rocker arm assembly and tighten nut (10). If nut (10) is 5/8 inch thread, tighten to a torque of 120 ± 15 N·m (89 ± 11 lb ft). If nut (10) is 1/2 inch thread, tighten to a torque of 70 ± 15 N·m (52 ± 11 lb ft).

End By:

1. Install the valve mechanism cover.