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SERIES 55 CRANKSHAFT VIBRATION DAMPER

A viscous type vibration damper is mounted on the front end of the crankshaft to reduce torsional vibration. See Figure 25247 . ‪

1.Viscous Vibration Damper ‪

3.Crankshaft Pulley Bolt ‪

2.Crankshaft Pulley ‪

Viscous Vibration Damper Mounting

The viscous damper assembly consists of a sealed outer shell, an internal flywheel, and a quantity of highly viscous fluid. See Figure 25257 . ‪

1.Crankshaft ‪

3.Damper Shell ‪

2.Viscous Fluid ‪

4.Internal Flywheel ‪

Viscous Vibration Damper Detail

During operation, the outer shell, which is firmly attached to the crankshaft, turns at the same speed as the crankshaft, its motion being transferred from the crankshaft through the fluid within the shell to the inner ring. Considerable inner ring slippage occurs as power impulses are transmitted through the crankshaft. This is desirable during flywheel acceleration and deceleration, since the damper lessens the vibration amplitude, reducing its effects to a harmless level. ‪

Repair or Replacement of Crankshaft Vibration Damper

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

Repair or Replacement of Crankshaft Damper Flowchart

Removal of Crankshaft Vibration Damper

Pre-cleaning is not necessary. ‪

To avoid injury from the projection of tools or other objects that may fall on or behind the vibration damper of an engine, always check and remove these items before starting the engine.

Remove the crankshaft vibration damper as follows: ‪

  1. Remove the six bolts retaining the front engine mount to the block. Remove the front engine mount.
  2. Remove the drive belts from the crankshaft pulley.
  3. Remove the inspection plug in the bottom of the flywheel housing, and install the flywheel lock, J 36375 . See Figure 25777 .

    1.Flywheel ‪

    2.Flywheel Housing ‪

    Flywheel Lock

  4. Thread the center screw of the tooth until the tip of the tool rests between two teeth of the flywheel ring gear.

    Note: It may be necessary to bar the engine over so that the center screw of the tool is exactly between two teeth. See Figure 25253 .

    1.Long Handled Breaker ‪

    2.Crankshaft Pulley ‪

    Barring Engine Over

  5. Tighten the knurled knob finger-tight.
  6. Remove two of the eight crankshaft pulley retaining bolts. (Choose two bolts 180 apart.)
  7. Install two guide studs, J 36325 , into the empty bolt holes.
  8. Remove the six remaining bolts.

    NOTICE:

    Carefully remove the crankshaft pulley. The vibration damper may come off with it. If the damper falls, it may be damaged internally. ‪

    NOTICE:

    Do not use a hammer, or pry the damper from the crankshaft. The outer shell may become dented and cause the inner ring to turn at the same speed as the outer shell. This will render the damper ineffective. ‪

  9. Remove crankshaft pulley. Refer to section .
  10. To remove the damper, slide it off the guide studs.
  11. Remove the flywheel lock and guide studs.
Inspection of Crankshaft Vibration Damper

Inspect the vibration damper as follows: ‪

  1. Inspect the outer damper casing for damage.
    1. Check for dents, fluid leaks, or bulges.
    2. If any are detected, replace with a new damper.
  2. Inspect the damper inner contact surfaces and the crankshaft end for damage. See Figure 25255 .

    Damper and Crankshaft Contact Surfaces

    1. Check for galling or burrs.
    2. Slight scratches or burrs may be removed with an emery cloth.
    3. If deep scratches are detected, replace the damper.
  3. Regardless of its condition, the damper should be replaced at normal engine overhaul, or whenever the engine has experienced a broken crankshaft.
  4. If the vibration damper has been damaged, also inspect the crankshaft. Refer to section . Crankshaft damage may have resulted.

Installation of Crankshaft Vibration Damper

Install the crankshaft vibration damper as follows: ‪

  1. Install the flywheel lockJ 36375 , in the inspection plug hole. See Figure 25777 .

    Note: It may be necessary to bar the engine over so that the center screw of the tool is exactly between two teeth. Use tool J 41594 to perform this procedure.

  2. Thread the center screw of the tool until the tip of the tool rests between two teeth of the flywheel ring gear.
  3. Tighten the knurled knob finger-tight.
  4. Install two guide studs,J 34691-A , in crankshaft pulley bolt holes 180 apart. Apply a light coat of anti-seize compound to the pilot diameter (not the crankshaft face) to ease future removal.
  5. Install the damper to the end of the crankshaft. The damper bolt holes are evenly spaced, so the damper may be installed in any position.
  6. Install the crankshaft pulley to the crankshaft. Refer to section .
  7. Install four bolts. Tighten the bolts finger-tight.
  8. Remove the guide studs.
  9. Install the remaining four bolts.
  10. Torque the bolts to 200-220 N m (148-162 lb ft) torque, proceeding in a clockwise direction.
  11. Remove the flywheel lock tool.
  12. Install the pipe plug into the flywheel housing inspection hole.
  13. Install the drive belts to the crankshaft pulley. Adjust belt tensions to the proper specifications. Refer to section .
  14. Install front engine mount.
  15. Install any other components removed for this operation.