D348 INDUSTRIAL & MARINE ENGINES Caterpillar


Variable Timing Unit

Usage:

Remove Variable Timing Unit

start by:

a) remove governor

1. On marine engines only, drain the jacket water cooling system. Remove clamp (2) and remove exhaust manifold inlet water line (3).

2. Remove oil line (1).

3. Remove cover (4) over the variable timing unit.

4. Bend lock (6) away from the bolts.

5. Remove the bolts, the lock and retainer (5).

6. Remove gear (7).

7. Remove the bolts, the locks and retainer (9).

8. Remove variable timing unit (8) from the engine.

Install Variable Timing Unit

1. Put variable timing unit (1) in position in the engine.

2. Install the retainer, the lock and the bolts that hold variable timing unit (1) in position.

3. Put gear (2) in position on the variable timing unit.

4. Put retainer (3) in position.

5. Install lock (4) and the bolts. Do not tighten the bolts.

6. Install the governor. See GOVERNOR REMOVAL AND INSTALLATION.

7. Adjust gear (2). See CHECKING FUEL INJECTION PUMP TIMING: ON ENGINE in TESTING AND ADJUSTING.

8. Install cover (5).

9. Install oil line (6).

10. On marine engines only, put exhaust manifold inlet water line (7) in position and install clamp (8). Fill the jacket water cooling system.

Disassemble And Assemble Variable Timing Unit

start by:

a) remove variable timing unit

1. Remove pins (1) from weights (2). Remove weights (2).

2. Remove plug (3). Turn retainer (4) with a screwdriver. Remove the retainer and spring (5).

3. Pull piston (10) out of the shaft.

4. Remove pin (11) from the coupling. Turn coupling (6) clockwise and remove it from the piston.

5. Remove pin (7) from the nut. Remove nut (12), spring (8) and valve (9) from piston (10).

NOTE: The following steps are for assembly of the variable timing unit.

6. Install valve (9), spring (8) and nut (7) on piston (10). Turn nut (7) until the distance (X) between bottom face of nut (7) and piston (10) is 1.914 ± .015 in. (48.62 ± 0.38 mm). Drill a .095 ± .002 in. (2.41 ± 0.05 mm) diameter hole through the nut and threaded port of the piston. Install the pin.

7. Install coupling (6) tight against the nut. Measure a distance of .156 in. (3.96 mm) from the top face of the nut and put a mark on the coupling. Drill a .095 ± .002 in. (2.41 ± 0.05 mm) diameter hole through the coupling and threaded portion of piston. Install the pin.

8. Install piston (10) in the shaft. Install spring (5) and retainer (4).

9. Install plug (3). The later variable timing nuts have a plug with an O-ring seal. The earlier variable timing units have a plug without an O-ring seal. For earlier variable timing units, tighten the plug to a torque of 75 ± 10 lb.ft. (100 ± 14 N·m).

10. Put weights (2) in position on the shaft and install pins (1). Make a mark (stake) with a punch at the pin holes in each end of the shaft to hold the pins in place. Each weight must move freely on its pin when installed.

end by:

a) install variable timing unit

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