PIN 4D7358 - Caterpillar

A service indicator may be mounted on the air cleaner element or in a remote location.
Illustration 1 g00947059
Some engines may be equipped with a different service indicator.Observe the service indicator. Clean the air cleaner element or replace the element when any of the following conditions occur:
The yellow diaphragm enters the red zone.
The red piston locks in the visible position.
The air restriction reaches 3.75 kPa (15 inch of H2O).Test the Service Indicator
Service indicators are important instruments.
Apply vacuum (suction) to the service indicator.
Reset the service indicator.If the yellow core does not latch at the greatest vacuum, or if service indicator does not reset easily, obtain a new service indicator. If the new service indicator will not reset, the fitting for the service indicator may be plugged.
Illustration 2 g00924884
A porous filter is part of the fitting that is used for mounting of the service indicator. Inspect the filter for cleanliness. Clean the filter, if necessary. Use compressed air or a clean, nonflammable solvent.Note: When service indicator is installed, excessive tightening may crack the top of the service indicator. Tighten the service indicator to a torque of 2 N m (18 lb in).Replace the service indicator annually regardless of the operating conditions.