MCI SERVICE INFORMATION

Air Filter - D/DL Coaches

The air system on the MCI coaches is basically divided into three sections. Air from the wet tank is distributed to the primary brake tank, secondary brake tank, and the accessory air tank. One way check valves isolate the two brake tanks, one on each tank. The air for the Accessory circuit goes through an inline air filter before continuing on to the pressure protection valve. This inline filter is located on the wet tank and looks very similar to the check valves.

This filter needs to be serviced regularly. The MCI preventative maintenance guideline recommends servicing this filter every 30,000 miles. If this filter begins to plug up, airflow to the accessory tank will be restricted.

One symptom of a plugged air filter is that the low air buzzer stays on longer. Instead of the buzzer shutting off at 75 - 85 pounds, the pressure gauge could read 110 pounds or higher. Another symptom is the air gauges going to 140 - 150 pounds before the air governor cycles and purges the dryer.

The compressor governor monitors the accessory air pressure. If the air supply is limited because of a plugged / dirty filter, the compressor will build too much air pressure in the rest of the coach.