Series 50

Section 16.7 Worn or Damaged Valve or Cylinder Kit

Section 16.7
Worn or Damaged Valve or Cylinder Kit

Loss of compression in Series 50 engines may result from a variety of sources, including worn or broken fire or compression rings, holes in pistons, leaky valves, scored or worn cylinder walls, leaky or broken gaskets and cracked cylinder heads or cylinder liners. The detection and elimination of the cause or causes of cylinder pressure losses is vital to engine life and efficient operation. To assist the mechanic in effectively measuring the loss of cylinder pressure, and locating the source of abnormal leaks in individual cylinders, the following test procedure has been developed.‪

  1. Move the vehicle requiring test to the chassis dynamometer; refer to OEM guidelines.
  2. Disconnect air compressor; refer to "10.1.2 Cleaning and Removal of Air Compressor" .
  3. Start the engine.
  4. Run the engine and bring the engine coolant temperature to normal operating range.
  5. Run vehicle to full load and rated speed.
  6. Attach a manometer calibrated to read in. H2 O, to the oil dipstick opening; refer to "29.1 Proper Use of Manometer" .
  7. Measure and record crankcase pressure.
  8. Shut down engine.
  9. Remove the vehicle from the chassis dynamometer.
  10. Review the crankcase pressure test results.
    1. If the crankcase pressure was greater than 3 in. H2 O (0.75 kPa); refer to "16.7.1 Worn or Damaged Valve or Cylinder Kit Repair" .
    2. If the crankcase pressure was less than 3 in. H2 O (0.75 kPa); refer to "29.2 Cylinder Compression Test" .
  11. Compare the cylinder compression test results to specifications.
    1. If cylinder pressure is below specifications, refer to "16.7.1 Worn or Damaged Valve or Cylinder Kit Repair" .
    2. If cylinder pressure is within specification, call Detroit Diesel Technical Service Group.

Section 16.7.1
Worn or Damaged Valve or Cylinder Kit Repair

Perform the following steps for worn or damaged valve or cylinder kit:‪

  1. Remove cylinder head; refer to "1.2.2 Removal and Cleaning of Cylinder Head" .
  2. Inspect the cylinder head for worn or damaged valves; refer to "1.2.3 Inspection of Cylinder Head" for repair and replacement procedures.
  3. Inspect for worn or damaged cylinder kit components:
    1. Inspect cylinder liner for damage, refer to "1.20.1 Repair or Replacement of Cylinder Liner" .
    2. Inspect piston and piston rings for damage, refer to "1.18.1 Repair or Replacement of Piston and Connecting Rod" .
  4. Verification of repairs made to cylinder valve(s) or cylinder kit components is required; refer to "16.7.1.1 Verification of Repair for Worn or Damaged Valve or Cylinder Kit" .
Section 16.7.1.1
Verification of Repair for Worn or Damaged Valve or Cylinder Kit

Perform the following to determine if the repaired valve or cylinder kit resolved the misfiring cylinder condition:‪

  1. Start the engine.
  2. Run the engine speed up to the occurrence of the misfiring.
  3. Listen for misfiring cylinder.
    1. If the engine is not misfiring, no further troubleshooting is required. Shut the engine down.
    2. If the engine is misfiring, call Detroit Diesel Technical Service Group. Shut the engine down.


Series 50 Service Manual - 6SE50
Generated on 10-13-2008

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