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SERIES 638 CRANKSHAFT VIBRATION DAMPER

A vibration damper is mounted on the front end of the crankshaft to reduce torsional vibration to a safe value. See Figure 27753 . ‪

1.Allen Head Bolt ‪

5.Crankshaft Pulley ‪

2.Lockwasher ‪

6.Front Cover ‪

3.Vibration Damper ‪

7.Damper Spacer ‪

4.Crankshaft Pulley Nut ‪

Vibration Damper Location

The vibration damper assembly consists of a sealed outer shell, an internal flywheel, and a quantity of viscous fluid. ‪

The outer shell, of the vibration damper is attached to the front pulley. The front pulley in turn is firmly attached to the crankshaft and turns at the same speed as the crankshaft, its motion being transferred to the flywheel through the fluid within the shell. Since fluid-drive" is more or less inefficient with frequent speed changes, considerable flywheel slippage will take place as power impulses are transmitted through the crankshaft. In this type of operation, the slippage is desirable since the acceleration and deceleration of the flywheel in the damper lessens the vibration amplitude, reducing its effect to a level harmless to the engine. ‪

Repair or Replacement of Crankshaft Vibration Damper

To determine if repair is possible or replacement is necessary, perform the following procedure. See Figure 21773 . ‪

Flowchart for Repair or Replacement of Crankshaft Vibration Damper

Removal of Crankshaft Vibration Damper

Precleaning is not necessary. ‪

Personal injury and/or engine damage may result from direct physical contact with the vibration damper of an operating engine. Damper damage, engine damage, or both may occur if tools or other objects strike or become lodged behind the damper during operation. Objects coming in contact with the damper of an operating engine also may be thrown off by the damper with force, becoming a dangerous projectile which could cause personal injury, property damage, or both. ‪

Remove the crankshaft vibration damper as follows: ‪

  1. Remove the fan assembly. Refer to section .
  2. Remove six Allen head bolts and lockwashers. See Figure 27754 .

    1.Allen Head Bolt (6) ‪

    4.Crankshaft Pulley ‪

    2.Lockwasher (6) ‪

    5.Front Cover ‪

    3.Vibration Damper ‪

    6.Damper Spacer ‪

    Crankshaft Vibration Damper Removal

  3. Remove the crankshaft vibration damper and damper spacer. See Figure 27754 .
Inspection of Crankshaft Vibration Damper

Inspect the vibration damper as follows: ‪

  1. Visually check the inner contact surfaces for gulled or burned surfaces.
    1. If the inner surfaces are galled or burred, repair with emery cloth. Otherwise, replace crankshaft vibration damper. Refer to section .
    2. If the inner surfaces are not galled or burred, proceed with step of inspection.
  2. Visually check the outer casting for dented, nicked, bulged surfaces or leaking vibration fluid.
    1. If the outer casting has dented, nicked, bulged surfaces or leaking viscous fluid, replace the crankshaft vibration damper. Refer to section .
    2. If the outer casting does not have dented, nicked, bulged surfaces or leaking viscous fluid, proceed with step of inspection.
  3. Visually check the crankshaft for breaks.
    1. If breaks are present, replace the crankshaft vibration damper. Refer to section .
    2. If no breaks are present, reuse the crankshaft vibration damper. Refer to section .

Installation of Crankshaft Vibration Damper

Install the crankshaft vibration damper as follows: ‪

  1. Install the spacer and crankshaft vibration damper to the front pulley. See Figure 27754 .

    1.Allen Head Bolt (6) ‪

    4.Crankshaft Pulley ‪

    2.Lockwasher (6) ‪

    5.Front Cover ‪

    3.Vibration Damper ‪

    6.Damper Spacer ‪

    Crankshaft Vibration Damper Installation

  2. Install six Allen head bolts with lockwashers and secure the crankshaft vibration damper to the front pulley. Torque the bolts to 47 N m (35 lb ft).
  3. Install the fan assembly. Refer to section .
  4. Run the engine to verify repair.