MACK RS 1977: SERVICE BRAKES, AIR:SUPPLY:HOSES, LINES/PIPING, AND FITTINGS

General Information

NHTSA Campaign ID Number: 78V030000

Make Model Year
MACK RS 1977
Date Owners Notified Date Received by ODI Date Added to Database
1978-08-23 1978-02-09 1979-10-12

Production Dates: 1975-12-01 - 1978-01-01

Manufacturers Involved: Mack Trucks, Inc.

Component: SERVICE BRAKES, AIR:SUPPLY:HOSES, LINES/PIPING, AND FITTINGS

Potential Number Of Units Affected: 400

Report Initiator: MFR MFR Report

Summary

A DESIGN DEFICIENCY EXISTS IN THE AIR DRYER PIPING IN THE AREA OF THE PRESSURE RELIEF VALVE AND COMPRESSOR GOVERNOR CONTROL LINK. MOISTURE IS PASSED AND BUILDS UP IN THIS RELIEF VALVE AND CONTROL LINE. IN FREEZING AMBIENT TEMPERATURES, THIS MOISTURE MAY FREEZE, ALLOWING THE CHASSIS AIR SYSTEM PRESSURE TO EXCEED 150 PSI. EXCESSIVE AIR SYSTEM PRESSURE CAN CAUSE SEPARATION OF AIR PIPING CONNECTIONS AND AIR SYSTEM VALVE FAILURE.

Remedy

THE DEALER WILL RELOCATE THE AIR SYSTEM COMPRESSOR GOVERNOR LINE AND PRESSURE RELIEF VALVE TO ELIMINATE MOISTURE ACCUMULATION.

Notes

VEHICLE DESCRIPTION: TRUCKS EQUIPPED WITH ANCHORLOK AIR DRYERS.SYSTEM: SERVICE BRAKES; AIR SYSTEM AND GOVERNOR CONTROL LINE 'AIR DRYER'.CONSEQUENCES OF DEFECT: WHEN THIS OCCURS, AUTOMATIC APPLICATION OF THE CHASSISEMERGENCY SPRING BRAKES AND TRAILER BRAKES COULD CAUSE LOSS OF VEHICLE CONTROLWITHOUT PRIOR WARNING AND A VEHICLE ACCIDENT.NOTE: OWNER/DRIVER IS ADVISED NOT TO OPERATE VEHICLE IF AIR PRESSURE EXCEEDS15O PSI.