621H, 623H and 627H Wheel Tractor-Scrapers Engine Supplement Caterpillar

Removal Procedure

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Illustration 1	g02589243

1. Remove bolts (1) and panel assembly (2) .

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Illustration 2	g02589245

2. Remove bolt (3). Remove bolts (5) and reposition tube assembly (4) .

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Illustration 3	g02639384

3. Disconnect tube assemblies (12). Disconnect cable assembly (6) .

4. Remove bolt (8).

5. Remove bolt (10) and the retainer. Disconnect harness assembly (11) .

6. Disconnect sensor assembly (14) .

7. Remove nuts (7), combustion head (13), the gasket, and the tube assembly.

8. Remove studs (9) .

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Illustration 4	g02640161

9. Remove connector assemblies (15), spark plug (16), adapter assembly (17), and adapter assembly (18) .

Installation Procedure

1. Install combustion head (13) in the reverse order of removal.

   1. Tighten adapter assembly (18) to a torque of 60 ± 6 N·m (44 ± 4 lb ft).

   2. Tighten adapter assembly (17) to a torque of 60 ± 6 N·m (44 ± 4 lb ft).

   3. Tighten spark plug (16) to a torque of 48 ± 4 N·m (35 ± 3 lb ft).

   4. Tighten connector assembly (15) to a torque of 30 ± 2 N·m (22 ± 1 lb ft).

   5. Tighten sensor assembly (14) to a torque of 45 ± 5 N·m (33 ± 4 lb ft).

   6. Apply Tooling (B) to the threads of studs (9). Tighten studs (9) to a torque of 17 ± 2 N·m (150 ± 18 lb in).

   7. Tighten nuts (7) in a crisscross pattern to a torque of 23 ± 3 N·m (204 ± 27 lb in). Tighten nuts (7) again in a crisscross pattern to a torque of 28 ± 3 N·m (21 ± 2 lb ft). Tighten nuts (7) again in a crisscross pattern to a torque of 28 ± 3 N·m (21 ± 2 lb ft).

   8. Tighten bolts (1) to a torque of 15 ± 3 N·m (133 ± 27 lb in).

   9. Perform th ARD ignition test. Refer to Troubleshooting Manual, "ARD Ignition - Test".