D349 INDUSTRIAL & MARINE ENGINES Caterpillar


Variable Timing Unit

Usage:

Remove Variable Timing Unit

preparatory step:

a) remove governor

1. Drain engine cooling system.

2. On Marine engines only, disconnect the water line from the support assembly, and remove the left exhaust manifold water inlet line.

3. On Industrial engines only, remove the left aftercooler water outlet line (1).

4. Remove the turbocharger inlet oil line (2). Remove the oil manifold mounting bolts (4).

5. Remove the variable timing unit cover (3).

6. Remove the variable timing unit drive gear, retainer, mounting bolts and lock.

7. Remove the variable timing unit retaining plate (5), bolts, and locks.

8. Remove the variable timing unit (6).

Install Variable Timing Unit

1. Position the variable timing unit in engine, and install retaining plate, bolts and lock.

2. Install the drive gear, retainer, mounting bolts and lock. Do not tighten the mounting bolts.

3. Time the fuel injection pump camshaft to the engine. See FUEL INJECTION PUMP CAMSHAFT TIMING in TESTING AND ADJUSTING.

4. Install the variable timing unit cover.

5. Install the turbocharger inlet oil line, and install the oil manifold mounting bolts.

NOTE: If the oil manifold gasket was damaged during removal, it will be necessary to install a new gasket.

6. On Industrial engines only, install the left aftercooler water outlet line.

7. On Marine engines only, install the left exhaust manifold water inlet line (1), and connect the water line (2).

8. Fill engine cooling system.

concluding step:

a) install governor

Disassemble Variable Timing Unit

preparatory step:

a) remove variable timing unit

1. Drive weight retaining pins from shaft assembly and remove the weights (1).

2. Remove the plug (2). Using a screwdriver, apply pressure and turn retainer (3). Remove the retainer and spring (4).

3. Pull the piston assembly out of shaft assembly.

4. Remove the coupling retaining pin (5). Rotate coupling (6) clockwise and remove from the piston assembly.

5. Remove the nut retaining pin (7). Remove the nut (8), spring (9) and valve (10) from the piston assembly (11).

Assemble Variable Timing Unit

1. Install the valve, spring and nut of piston assembly. Adjust the nut until the distance between bottom face of nut and piston is 1.760 ± .010 in. (44,70 ± 0,25 mm). Drill a .095 ± .002 in. diameter hole through the nut and threaded portion of piston assembly. Install retaining pin.

2. Install the coupling tight against the nut. Measure .156 in. (3,96 mm) from the top face of nut and mark this location on coupling. Drill a .095 ± .002 in. diameter hole through the coupling and threaded portion of piston assembly at this location. Install retaining pin.

3. Install the piston assembly in shaft assembly. Install the retainer and spring. Install plug.

4. Position the weights on shaft assembly and install the retaining pins. Stake the retaining pins at one place of both ends of pin hole in shaft assembly. Each weight must pivot freely on its pin when installed.

concluding step:

a) install variable timing unit

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