CONNECTOR-PORT 3R6790 - Caterpillar

All 3306 and 3406 Truck EnginesReference: Truck Engine News, August 1991, Page 3, "California Laws Target Excessive Smoke."Some states, such as Illinois, have adopted new laws placing restrictions on truck engine smoke emission levels. These states have patterned laws after those enacted in California. The new laws regulate smoke by measuring smoke opacity during a snap idle, load acceleration test. The test is for all on-road vehicles over 8000 lbs GVWR.
The smoke level is measured by an opacity meter and documented with a strip chart recorder. The smoke limits in Illinois are 55% opacity maximum for all pre-1991 model year engines and 40% opacity for 1991 and later model years.
In Illinois, the strict enforcement of the new regulations and the date of implementation have not been established. However, regardless of the new smoke regulations, it is very important to follow the maintenance recommendations in the Operation and Maintenance Manual in a timely manner to help ensure optimum engine performance. The presence of excessive smoke may indicate an engine that is out of adjustment and/or suffering from excessive component wear. Excessive smoke can also be an indicator of poor fuel economy and performance.