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 air compressor, refer to appropriate service manual, special equipment chapter.
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 inches of water, to the oil dipstick opening.
Measure and record the crankcase pressure.
7. Shut down engine.
8. Remove the vehicle from the chassis dynamometer.
9. Review the crankcase pressure test results.
[a] If the crankcase pressure exceeds 1.25 kPa (5 in. H2O), repair worn or damaged valve(s) or cylinder kit; refer to section 6.5.1.
[b] If the crankcase pressure was less than or equal to 1.25 kPa (5 in. H2O), perform cylinder compression test.Refer to section 6.5.1.2.
10. Compare the cylinder compression test results to specifications.
[a] If the cylinder compression is below specifications, repair worn or damaged valve(s) or cylinder kit; refer to section 6.5.1.
[b] If the cylinder compression is within specification, call Detroit Diesel Customer Support Center (313-592-5800).
6.5.1
Worn or Damaged Valve(s) or Cylinder Kit(s) Repair
Perform the following steps to repair worn or damaged valve(s) and cylinder kit(s):
1. Remove cylinder head; refer to appropriate service manual, engine chapter.
2. Inspect the cylinder head for worn or damaged valves; refer to appropriate service manual, engine chapter.
3. Inspect the cylinder kit components for worn or damaged liners, pistons or piston rings; refer to appropriate service manual, engine chapter.
4. Replace damaged cylinder kit components; refer to appropriate service manual, engine chapter.
5. Verify repairs made to cylinder head valve(s) or cylinder kit components; refer to section
6.5.1.1.
6.5.1.1
Test Engine with Repaired Cylinder Head Valve(s), and Cylinder Kit
Refer to section 6.5 for exhaust caution before proceeding. To determine if the cylinder head valve and cylinder kit repair resolved the excessive oil consumption.
1.Perform a crankcase pressure test if reading is below 1.25 kPa (5psi) no further
troubleshooting is required.
2. If the crankcase pressure test is reading over.25 kPa (5 psi), call the Detroit Diesel
Customer Support Center at 313–592–5800.
6.5.1.2
Cylinder Compression Test
