LEVER AS 7V3518 - Caterpillar

Service the air cleaner only with the engine stopped. Engine damage could result.
Raise the hood.Note: The engine air filter service indicator has four indicator sight glass windows. Two sight glasses are normally yellow and two smaller sight glasses are normally green. The yellow sight glasses should gradually turn a red color. The red color is a relationship to the restriction that is at the air filter. You may use the yellow sight glasses to estimate the condition of your air filter. You may want to rotate the air filter service indicator in order to have a better view of the green sight glass. Do not overtighten the air filter service indicator.
Illustration 1 g00635850
The engine air filter service indicator (1) is located next to the primary fuel filter. If the normally green window on engine air filter service indicator (1) is completely red, service the air filter.
In order to reset engine air filter service indicator (1), push in on the bottom of the engine air filter service indicator.
Refer to the Operation and Maintenance Manual, "Engine Air Filter Primary Element - Clean/Replace".
Refer to the Operation and Maintenance Manual, "Engine Air Filter Secondary Element - Replace".
Lower the hood.