1992 MACK CH recalls

VEHICLE DESCRIPTION: HEAVY DUTY CLASS 8 TRUCKS EQUIPPED WITH FONTAINE FIFTH WHEEL ASSEMBLIES. THE FIFTH WHEEL MOUNTING PLATES CAN CRACK.

UNDER THE TRAILER LOADING, THE MOUNTING PLATE COULD EVENTUALLY FAIL DUE TO FATIGUE.

DEALERS WILL INSPECT AND REPLACE THE MOUNTING PLATES THAT ARE CRACKED.

THE ENGINE COOLING FAN BLADES MAY BREAK DUE TO INADEQUATE BLADE STRENGTH AROUND THE RIVETS THAT ATTACH THE BLADES TO THE FAN SPIDER.

IF COMPLETE FRACTURE OF THE FAN BLADE OCCURS, IT COULDBE PROPELLED OUTSIDE THE FAN SHROUD, INJURING PERSON(S) IN THE VICINITY OFTHE TRUCK.

AN IMPROVED FAN WILL BE INSTALLED ON THESE VEHICLES.

FUEL INJECTION SYSTEM RECONFIGURATION TO COMPLY WITH ENGINE EMISSION STANDARDS CAUSE HIGHER ENGINE VIBRATION LEVELS WHICH LEAD TO EARLY WEAR AND COMPLETE FAILURE OF THE SECONDARY THROTTLE RETURN MECHANISM.

IN THE EVENT THE PRIMARY THROTTLE RETURN FAILS, FAILURE OF THE SECONDARY THROTTLE RETURN SYSTEM WOULD NOT PROVIDE PROTECTION AGAINST LOSS OF THROTTLE CONTROL.

A NEW PRODUCTION SECONDARY THROTTLE RETURN SYSTEM CONFIGURATION WILL BE INSTALLED.

THE CARRIER YOKE BOLTS WERE MANUFACTURED WITH WORN ROLLING THREAD DIES, CAUSING STRESS CONCENTRATIONS WHICH CAUSED CRACKS DURING THE QUENCHING PROCESS.

THIS CONDITION CAN CAUSE BOLT FAILURE AND ALLOW THEDRIVELINE TO SEPARATE FROM THE CARRIER ASSEMBLY.

REPLACE THE CARRIER YOKE BOLTS.

THE DRIVESHAFT CENTER BEARING SUPPORT BRACKET CAN CRACK AND BREAK.

IF THIS HAPPENS, THE DRIVESHAFT WILL WOBBLE AND CAN SEPARATE. SEPARATION CAN RESULT IN DAMAGE TO OTHER COMPONENTS OF THE VEHICLE OR LOOSE FRAGMENTS CAN FALL ONTO THE ROADWAY PRESENTING A HAZARD TO OTHER DRIVERS.

DEALERS WILL REPLACE THE CENTER BEARING HANGER BRACKET.

AIR SYSTEM BLOCKAGE IN THE AIR DRYER OCCURS DEGRADING THE MOISTURE REMOVING CAPABILITIES OF THE DRYER WHEN THE VEHICLE IS OPERATED IN A COLD ENVIRONMENT AND MOISTURE ACCUMULATES AND FREEZES IN THE AIR DRYER OR IN THE LINE BETWEEN THE DRYER AND THE AIR SYSTEM RESERVOIR. THE AIR DRYER CAN BECOME OVERPRESSURIZED CAUSING THE AIR DRYER CARTRIDGE TO SEPARATE FROM THE MOUNTING BASE.

IF THE AIR DRYER SEPARATES FROM THE BASE, THE CARTRIDGE CAN SEPARATE SUFFICIENTLY ENOUGH TO CAUSE PERSONAL INJURY OR PROPERTY DAMAGE.

DEALERS WILL EQUIP AIR SYSTEMS WITH A PRESSURE RELIEF VALVE TO BE LOCATED BETWEEN THE COMPRESSOR AND THE AIR DRYER. THIS PRESSURE RELIEF VALVE IS INTENDED TO VENT IF EXCESSIVE PRESSURE DEVELOPS IN THE AIR DRYER.