MBE 4000 DDEC VI Troubleshooting – Section 9.4 Faulty Exhaust System

Section 9.4
Faulty Exhaust System

To determine if a faulty exhaust system is causing excessive black or gray exhaust smoke, perform the following:‪

1. Drill an 11/32 in. hole in the exhaust pipe, 125 - 305 mm (5 - 12 in.) from the turbocharger exhaust outlet.

   Note: The tapped hole must be in a comparatively straight section of the turbocharger exhaust outlet.

2. Tap the hole to accommodate a 1/8 in. pipe plug.
3. Connect a manometer calibrated to read pressure in kPa or inches of Hg to the tapped hole.

   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.‪

4. Start and run the engine.
5. Run the engine at idle with a no-load condition for approximately five minutes, allowing the engine coolant to reach normal operating range, approximately 88-96°C (190-205°F).
6. Run the engine speed to full load.
   1. If the exhaust back pressure at full load is less than 12 kPa (3.5 in. Hg), check the fuel injectors and nozzles; refer to "9.6 Faulty Fuel Nozzle" . Shut down the engine.
   2. If the exhaust back pressure at full load is 12 kPa (3.5 in. Hg) or greater, refer to "9.4.1 Engine Exhaust System Resolution" . Shut down the engine.

Section 9.4.1
Engine Exhaust System Resolution

Perform the following steps to resolve the engine exhaust system concern:‪

1. Visually inspect the engine exhaust system: refer to OEM guidelines.
2. Repair and replace defective exhaust system components; refer to OEM guidelines
3. Verify exhaust system resolutionrefer to "9.4.1.1 Test the Engine with Replaced Exhaust System" .

Section 9.4.1.1
Test the Engine with Replaced Exhaust System

Perform the following steps to determine if replaced engine exhaust manifold has resolved the excessive black or gray exhaust smoke condition:‪

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. Start and run the engine.
2. Run the engine at idle with a no-load condition for approximately five minutes, allowing the engine coolant to reach normal operating range, approximately 88-96°C (190-205°F).
3. Visually inspect exhaust for excessive smoke.
   1. If the engine exhaust emission appears normal, no further troubleshooting is required. Shut down the engine.
   2. If the engine exhaust emission is excessively black or gray, shut down the engine. Check the fuel nozzles; refer to "9.5 Aerated Fuel" .