Detroit Diesel Troubleshooting Diagrams

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.
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.
If the crankcase pressure exceeds 0.75 kPa (3 in. H 2 O), repair worn or damaged valve(s) or cylinder kit; r
If the crankcase pressure was less than or equal to 0.75 kPa (3 in. H 2 O), perform cylinder compression test.
10. Compare the cylinder compression test results to specifications.
If the cylinder compression is below specifications, repair worn or damaged valve(s) or cylinder kit;
If the cylinder compression is within specification, call Detroit Diesel Technical Service Group

To determine if a defective turbocharger is causing excessive oil consumption, perform the following: ‪

1. Remove the turbocharger drain line connected to the crankcase and place the drain line into a suitable container.
2. Perform a crankcase pressure test.

If the engine crankcase pressure is less than 0.75 kPa (3 in. H 2 O), replace the turbocharger;
If the engine crankcase pressure is 0.75 kPa (3 in. H 2 O) or more, check for worn or damaged valve and cylinder kit;

To determine if a defective air compressor is causing excessive oil consumption, perform the following: ‪

1. Perform a crankcase pressure test and record the test results.
2. Disconnect the air outlet line from the air compressor;

3. Repeat step and record the test results.
4. Compare the results of test one with test two.

If the engine crankcase pressure remained the same, check the turbocharger;
If the engine crankcase pressure decreased, replace the air compressor

To determine if a leaking oil cooler core is causing excessive oil consumption, perform the following: ‪

1. Check for oil in the engine coolant or radiator.
If oil is present in either the engine coolant or radiator;
If no oil is present in either the engine coolant or radiator, check for a defective air compressor;
2. Remove the oil cooler core and housing;
3. Clean both the oil side and water side of oil cooler core;
4. Perform an oil cooler core pressure test;
5. Visually check to see if air bubbles are rising to the surface of the water within the container.
If air bubbles are present
If no air bubbles are present, complete a lube oil consumption report, call the Detroit Diesel Technical Service Group for a form.

To determine if oil leaks are causing excessive oil consumption, perform the following:

1. Start and run the engine to operating temperature 88 ° C (190 ° F).
2. Check for leaks at oil lines, connections, mating joints, seals, and gaskets

If no oil leaks are found, shut down the engine and check for a leaking oil cooler core;
If oil leaks are found, shut down the engine;

Engine Oil Leak Repair

Perform the following steps, as necessary, to resolve engine oil leaks: ‪

1. Repair or replace components leaking oil;
2. Verify repairs made to correct oil leaks;

To determine if an overfilled crankcase is causing excessive oil consumption, perform the following: ‪

1. Ensure vehicle is parked on level ground.
2. Perform a universal dipstick calibration check; refer to SIB 12-60-94R (May 1995).

1. If the calibration check indicates that the oil level is off by more than 2 mm (0.078 in.), contact your Detroit Diesel regional support office.
2. Check for oil leaks;