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SERIES 55 ENGINE BRAKE EXHAUST VALVE

The cylinder head engine brake provides increased braking performance by opening a decompression valve in each cylinder head. The decompression valves are pneumatically actuated through a connection to the vehicle air brake supply tank or a hydraulic pump mounted on the upper front cover. See Figure 25739 . ‪

Note: The engine oil brake assembly and the engine air brake assembly are serviced the same. Only the part numbers differ.

Repair or Replacement of Engine Brake Flowchart

Removal of Engine Brake

Pre-cleaning is not necessary. ‪

Note: The cylinder head must be removed to perform maintenance on the engine exhaust brake valve. Failure to remove the cylinder head from the engine could result in damage to the cylinder head internal components or engine.

Remove the engine exhaust brake valve as follows: ‪

  1. Remove cylinder head. Refer to section .
  2. Position cylinder head on work table.
  3. Remove the injector nozzle hold down crab. Refer to section .
  4. Remove the engine exhaust brake cover.
  5. Using valve spring compressor J-41587 with fork attachment J-41587-4 and support J-41587-5, compress the valve spring, remove the valve keepers using a magnet or long nose pliers. See Figure 25467 .

    1.Cylinder Head ‪

    4.Fifth Valve Cover ‪

    2.Piston ‪

    5.Valve Keepers ‪

    3.Oil Seal ‪

    6.Wing Nut ‪

    Valve Spring Compressor Tools

  6. Remove the valve spring compressor and attachments. See Figure 25467 .
  7. Remove the upper valve seat, spring, and lower valve seat.
  8. Remove engine brake valve from cylinder head. See Figure 25468 .

    1.Cylinder Head ‪

    4.Engine Brake Valve Spring ‪

    2.Lower Valve Seat ‪

    5.Engine Brake Valve ‪

    3.Upper Valve Seat ‪

    Engine Brake Removal

Inspection of Engine Brake

Inspect the engine brake components as follows: ‪

  1. Inspect the engine brake components.
    1. Inspect the engine brake valve components for stress cracks, gouge marks, bent valve stem, or a poor seating surface.
  2. Inspect cylinder head. Refer to section .
    1. Inspect the cylinder head engine brake bore for cracks or gouges.
    2. If damage is severe, replace the cylinder head.
    3. Check for galling or burrs.
    4. Minor galls or burrs may be smoothed with an emery cloth.
    5. If galls or burrs are major, replace the cylinder head.

Installation of Engine Brake

Install the engine brake as follows ( see Figure 25468 ): ‪

1.Cylinder Head ‪

4.Engine Brake Valve Spring ‪

2.Lower Valve Seat ‪

5.Engine Brake Valve ‪

3.Upper Valve Seat ‪

Engine Brake Installation

  1. Install the engine brake valve through the cylinder head bore.
  2. Install lower valve seat, spring, upper valve seat.
  3. Install the valve spring compressor J-41587 with fork attachment J-41587-4 and support J-41587-5. See Figure 25467 .

    1.Cylinder Head ‪

    4.Fifth Valve Cover ‪

    2.Piston ‪

    5.Valve Keepers ‪

    3.Oil Seal ‪

    6.Wing Nut ‪

    Valve Spring Compressor Tools

  4. Using long nosed pliers, compress the valve spring enough to install the valve keepers.

    NOTICE:

    Valve keepers must be properly positioned. Failure to position keepers will result in poor engine brake performance, serious engine damage, or both. ‪

  5. Remove the spring compressor and adaptor.
  6. Install the engine exhaust brake cover. Refer to section .
  7. Install the injector nozzle hold down crab. Torque mounting bolts to 65 N m (48 lb ft). Refer to section .
  8. Install the cylinder head. Refer to section .