Series 60 DDEC VI Troubleshooting – Section 4.12 Low Compression

Section 4.12
Low Compression

To determine if low compression is causing starting difficulty, perform the following steps:‪

1. Perform a cylinder compression test.Refer to "4.12.1.2 Cylinder Compression Test" .
2. Compare cylinder compression test results to specifications.
   1. If cylinder pressure is below specifications; refer to "4.12.1 Low Compression Repair" .
   2. If cylinder pressure is within specifications, call Detroit Diesel Customer Support Center (313-592-5800).

Section 4.12.1
Low Compression Repair

Perform the following steps for low compression repair:‪

1. Remove cylinder head; refer to the appropriate service manual, engine chapter.
2. Inspect the cylinder head for worn or damaged valves; refer to the appropriate service manual, engine chapter.
3. Replace damaged valves; refer to the appropriate service manual, engine chapter.
4. Inspect the cylinder kit components for worn or damaged liners, pistons or piston rings; refer to the appropriate service manual, engine chapter.
5. Verify repairs made to cylinder head valve(s) or cylinder kit components; refer to "4.12.1.1 Test Engine with Repaired Cylinder Head Valve(s), and Cylinder Kit" .

Section 4.12.1.1
Test Engine with Repaired Cylinder Head Valve(s), and Cylinder Kit

Perform the following steps to determine if the cylinder head valve and cylinder kit repair resolved starting difficulty:‪

1. Attempt to start and run the engine. If the engine starts and runs, no further troubleshooting is required. Shut down the engine.
2. If the engine fails to start and run, call the Detroit Diesel Customer Support Center at 313–592–5800.

Section 4.12.1.2
Cylinder Compression Test

Perform the following steps for a compression test on a Series 60 Engine:‪

PERSONAL INJURY ‪
To avoid injury from inhaling engine exhaust, always operate the engine in a well-ventilated area. Engine exhaust is toxic.‪

1. Start and run the engine until normal operating temperature is reached. Stop the engine.
2. Disconnect the batteries.
3. Disconnect the fuel pump feed line from the fuel tank. Place a suitable container under the line to catch the spilling fuel. Turn the ¼ turn valve off on the outlet fitting of the secondary fuel filter.
4. Disconnect the fuel supply line to the cylinder head. Place a suitable container under the line to catch the spilled fuel. Disconnect the fuel return line from the doser valve and place a suitable container under the line to catch the spilled fuel.

   EYE INJURY ‪
   To avoid injury from flying debris when using compressed air, wear adequate eye protection (face shield or safety goggles) and do not exceed 276 kPa (40 psi) air pressure.‪

   NOTICE: ‪

   All the fuel must be removed from the cylinder head before removing injectors. This prevents the fuel from entering the cylinder and causing cylinder wall lube oil wash down or a hydrostatic lock at startup.‪

5. Blow low pressure regulated air no more than 207 kPa (30 psi ) into the inlet fitting for 20 to 30 seconds or until all the fuel is purged from the head.
6. Clean and remove the rocker cover, it is not necessary to remove the bottom rocker cover. If equipped with Jake Brakes remove the Jake Brake assembly.
7. Remove all the rocker shaft mounting bolts and nut from the front or rear rocker shaft assembly. Using rocker arm lifter (J–35996–A) , see Figure "Rocker Arm/Shaft Assembly Removal/Installation" , lift the assembly straight up and off of the head and place in a clean area on the bench.
   

   Figure 1. Rocker Arm/Shaft Assembly Removal/Installation

8. Use tool J-47808 to remove the 4–pin electrical connection from the injector.
9. Disengage the locking tang on the harness plug connection, grasp the connector and gently pull it from the socket.
10. Remove the injector hold down clamps.

    NOTICE: ‪

    Use extreme care when handling injectors to avoid costly damage by dropping or mishandling. Always install new O-rings when replacing injectors.‪

11. Remove the three injectors to be tested from the cylinder head.
12. Place the compression test adaptors (J-47373) into the injector holes. It is recommended to have three test adaptors (J-47373) when performing this routine.
13. Install the injector hold down clamps and torque hold down bolts to 58-66 N·m (43-49 lb·ft).
14. Carefully remove the shaft from the rocker arm assembly by slowly pulling it out of the assembly. Place the shaft on the bench. Do not disturb the stack-up of the rocker arm sets.
15. Remove the three injector rocker arms and replace with spacers (J–38768–5) .
16. Lubricate the shaft with clean engine oil. With sleeves in place, carefully reinstall the shaft through each rocker arm shaft. Make sure cup plug end faces inboard.
17. Install the modified rocker arm shaft assembly on the head. If the engine is equipped with a Jake Brake®, use non-Jake Brake rocker arm shaft bolts 8929129. Torque the three bolts and the nut to 102-108 N·m (75-80 lb·ft).

    Note: Verify that the bolt holes for the rocker shafts are clean as not to hydro lock the bolts causing damage to the cylinder head.

18. Disconnect both connectors at the valve cover for the injectors.

    Note: Disconnect both connectors at the valve cover for the injectors.

    PERSONAL INJURY ‪
    To avoid injury when working on or near an operating engine, wear protective clothing, eye protection, and hearing protection.‪

    PERSONAL INJURY ‪
    To avoid injury from hot surfaces, wear protective gloves, or allow engine to cool before removing any component.‪

19. Attach cylinder compression gauge (J–6692–B) to the first adaptor. See Figure "Attach Cylinder Compression Gauge J–6692–B" .
    

    Figure 2. Attach Cylinder Compression Gauge J–6692–B

20. Reconnect the batteries.
21. Crank the engine over using the starter motor 5 compression strokes record the compression reading on the gauge.

    Note: Verify that the batteries voltage does not go low enough to affect engine cranking speed. If the cranking speed is affected then the results will be inaccurate. If needed connect a battery charge to maintain battery voltage.

22. The compression reading should be 3102-3793 kPa (450-550 psi) with no two cylinders differing by more than 276 kPa (40 psi). If compression readings are below specifications, repeat step 20 to be certain of the reading.
23. After testing all three cylinders, remove bolts from the modified rocker arm shaft assembly and, using rocker arm lifter (J–35996), lift the assembly straight up and off the cylinder head. Place in a clean area on the bench.
24. Carefully remove the shaft from the rocker arm assembly, remove the three rocker arm sleeves. Replace the three injector rocker arms. Lubricate the shaft with clean engine oil and carefully reinstall through each rocker arm.
25. Remove the injector hold down clamps discard the hold down bolt and remove the compression test adaptors from the cylinder head.
26. Using new sealing rings and injector hold down bolt install the injectors back into the cylinder head and torque to specifications; Torque bolt to 50 Nm (37 lb ft) Loosen the bolt 60 degrees ( 1/6 of a turn or one bolt flat) Do not fully loosen the bolt. Torque the bolt to 35 Nm (26 lb ft) Tighten the bolt an additional 90 degrees.
27. Replace the completed rocker arm shaft assembly on the engine and torque nut and bolts to specifications torque to 102-108 N•m (75-80 lb•ft)
28. Repeat steps 4b-26 for the rear 3 cylinders
29. Install upper valve cover, insuring that the bolt hole are clear of dirt and oil as not to damage the lower rocker cover.
30. Check test results