MBE 4000 DDEC VI Troubleshooting – Section 9.15 Low Compression

Section 9.15
Low Compression

To determine if low compression is causing excessive exhaust smoke, perform the following steps:‪

1. Perform a cylinder compression test; refer to "2.2 Compression Pressure Test" .
2. Compare cylinder compression test results to specifications as listed in Table "Compression Testing Specifications" .

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

   Table 1. Compression Testing Specifications
   1. If cylinder compression pressure is below specifications, refer to "9.15.1 Low Compression Repair" .
   2. If cylinder compression pressure is within specifications, call Detroit Diesel Customer Support Center at 313-592-5800.

Section 9.15.1
Low Compression Repair

Perform the following steps for low compression repair.‪

1. Remove cylinder head; refer to MBE 4000 Service Manual (6SE420), Chapter 1, “Engine — Cylinder Head”.
2. Inspect the cylinder head for worn or damaged valves; refer to MBE 4000 Service Manual (6SE420), Chapter 1, “Engine — Valves”.
3. Replace damaged valves; refer to MBE 4000 Service Manual (6SE420), Chapter 1, “Engine — Valves”.
4. Inspect the cylinder kit components for worn or damaged liners, pistons; or piston rings.
5. Verify repairs made to cylinder head valve(s) or cylinder kit components have corrected the excessive exhaust smoke concern; refer to "9.15.1.1 Test Engine with Repaired Cylinder Head Valve(s), and Cylinder Kit" .

Section 9.15.1.1
Test Engine with Repaired Cylinder Head Valve(s), and Cylinder Kit

To determine if the cylinder head valve and cylinder kit repair resolved excessive exhaust smoke, perform the following steps:‪

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.‪

1. Attempt to start and run the engine, if the engine starts and runs without excessive exhaust smoke, no further troubleshooting is required. Shut down the engine.
2. If the engine continues to have excessive exhaust smoke, call the Detroit Diesel Customer Support Center at 313-592-5800.