To determine if a faulty exhaust system is causing excessive exhaust smoke, perform the following:
1. Drill an 11/32 in. hole in the exhaust pipe, 5 to 12 in. (127 – 305 mm) from the turbocharger exhaust outlet.
Note: The tapped hole must be in a comparatively straight area of the turbocharger exhaust outlet.
2. Tap the hole to accommodate an 1/8 in. pipe plug.
3. Connect a manometer to the tapped hole.
4. Start and run the engine.
5. Run the engine at idle with a no-load for approximately 5 minutes, allowing the engine coolant to reach normal operating range.
6. Run the engine speed to full load.
If the exhaust back pressure at full load is less than 3.0 in. Hg (10.1 kPa), check the fuel injectors.
If the exhaust back pressure at full load is 3.0 in. Hg (10.1 kPa) or greater