BASE GP-VALVE COVER 3111467 - Caterpillar

The fuel settings on on-highway truck engines must be adjusted to EPA-approved specifications by a serviceman who has had the necessary training for fuel system maintenance.
To keep smoke and soot at an acceptable level:
1. Use the correct tools and a dial indicator to make sure the air fuel ratio control is set at the specification shown in the fuel setting microfiche. Also, during the adjustment procedure make sure the engine is at normal operating temperature and approximately 800 rpm. This will permit consistent results. Do not try to set the air fuel ratio control visually (without a dial indicator). If the air fuel ratio control is set visually, the setting is usually to high (rich).2. Periodically, check the air fuel ratio control for correct operation. To do this, install a dial indicator to make sure that the setting repeats itself.Some other possible causes for high levels of soot in the engine oil are: 1. A restriction in the air intake or exhaust system.2. Extended oil and filter change intervals.3. Worn pistons rings and cylinder liners.4. Excessive fuel settings.5. Wrong fuel.6. A turbocharger which does not operate correctly.