MBE 4000 DDEC VI Troubleshooting – Section 7.6 Worn or Damaged Valve or Cylinder Kit

Section 7.6
Worn or Damaged Valve or Cylinder Kit

A loss of cylinder pressure can cause increased oil consumption. The detection and elimination 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 the air compressor and remove; refer to MBE 4000 Service Manual (6SE420), Chapter 11, “Special Equipment”.

   PERSONAL INJURY ‪
   To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked.‪

3. Start the engine.
4. Run the engine and bring the engine coolant temperature to normal operating range, approximately 88–96°C (190–205°F).
5. Run the vehicle to full load and rated speed.
6. Perform a crankcase pressure test; refer to "2.1 Crankcase Pressure Test" .
7. Shut down the engine.
8. Remove the vehicle from the chassis dynamometer.
9. Review the crankcase pressure test results.
   1. If the crankcase pressure exceeds 0.62 kPa (2.5 in. H₂ O), repair worn or damaged valve(s) or cylinder kit; refer to "7.7 Worn or Damaged Valve(S) or Cylinder Kit(S) Repair" .
   2. If the crankcase pressure was less than or equal to 0.62 kPa (2.5 in. H₂ O), perform a cylinder compression test; Refer to "2.2 Compression Pressure Test" .
10. Compare the cylinder compression test results to specifications as listed in Table "Compression Testing" .
    1. If the cylinder compression is below specifications, repair worn or damaged valve(s) or cylinder kit; refer to "7.7 Worn or Damaged Valve(S) or Cylinder Kit(S) Repair" .
    2. If the cylinder compression is within specifications, call Detroit Diesel Customer Support Center (313-592-5800).

       Description‪	Pressure kPa (psi)‪
       Compression Pressure at Starter Speed‪	2800 (406)‪
       Permissible Difference Between Individual Cylinders‪	400 (58)‪

       Table 2. Compression Testing