Mack U SERIES recalls by model year

Reported: 1980-05-06 (May 6, 1980) · Model years: 1976, 1977, 1978, 1979, 1980

THE PREFABRICATED PINCH BOLT CLAMP AT THE LOWER STEERING SHAFT LOWER YOKE MAY NOT PERFORM ADEQUATELY WHEN TIGHTENED TO SPECIFICATIONS. THE CLAMP MAY THEN DEFORM AND LOSS OF CLAMPING FORCE AND STEERING SHAFT DISENGAGEMENT MAY RESULT.

Remedy: DEALER WILL RETROFIT WITH LOWER STEERING SHAFT LOWER YOKES THAT PROVIDE FOR INTEGRAL PINCH BOLT INSTALLATION IN PLACE OF PREVIOUS SEPARATELY FABRICATED CLAMP FOR THE PINCH BOLT.

Reported: 1980-05-06 (May 6, 1980) · Model years: 1979, 1980

ON CERTAIN VEHICLES, THE KNOB THAT OPERATES THE TRACTOR PARK VALVE MAY BREAK OFF, RENDERING THE VALVE INOPERABLE.

Remedy: DEFECTIVE KNOBS WILL BE REPLACED WITH AN IMPROVED TYPE, WITHOUT CHARGE TO OWNER.

Reported: 1981-07-08 (July 8, 1981) · Model years: 1979, 1980

THE RETAINING PIN FOR THE BRAKE CONTROL KNOB HAS BEEN MISALIGNED (OFF THE CENTER LINE OF THE VALVE PLUNGER HOLE). THIS CAUSES THE KNOB TO BE OVERSTRESSED AT THE RETAINING PIN HOLE AREA CAUSING IT TO SEPARATE FROM THE VALVE.

Remedy: THE HOLES WILL BE RETOOLED TO PROVIDE CORRECT ALIGNMENT AND PLASTIC KNOBS WILL BE REPLACED BY KNOBS OF STRONGER MATERIAL HAVING METAL REINFORCEMENTS.

Reported: 1982-03-02 (March 2, 1982) · Model years: 1980, 1981, 1982

CERTAIN VEHICLES MAY BE SUBJECT TO STEERING SHAFT SEPARATION DUE TO LOOSE SET SCREWS IN THE DASH SHEET BEARING WHICH MAY ALLOW THE SHAFT TO MOVE.

Remedy: DEALER WILL INSPECT AND MODIFY THE STEERING SHAFT BY PROVIDING A GREATER SLIP LENGTH IN THE STEERING DRIVE SHAFT TO ELIMINATE SLIP JOINT SEPARATION.

Reported: 1984-03-22 (March 22, 1984) · Model years: 1983, 1984

IMPROPER STEERING CLAMP BOLTS AND TORQUE APPLIED DURING INSTALLATION. THE BOLT COULD FAIL, ALLOWING THE STEERING YOKE TO BECOME LOOSE.

Remedy: INSPECTION AND, IF NECESSARY, INSTALLATION OF PROPER STEERING SHAFT CLAMP BOLTS TIGHTENED TO SPECIFICATIONS.

Reported: 1987-11-23 (November 23, 1987) · Model years: 1987

CROSS STEERING LEVERS MAY BE IMPROPERLY HEAT TREATED AND SUBJECT TO FAIL DURING NORMAL OPERATION.

Consequence: SUCH FAILURE COULD CAUSE LOSS OF TRUCK CONTROL WITHOUTPRIOR WARNING AND RESULT IN A CRASH.

Remedy: INSTALL NEW, PROPERLY HEAT TREATED STEERING LEVER.

Reported: 1989-03-03 (March 3, 1989) · Model years: 1987, 1988

AN INCORRECT HIGH PRESSURE POWER STEERING HOSE MAY HAVE BEEN INSTALLED.

Consequence: UNDER CERTAIN CONDITIONS, HOSE COULD FAIL RESULTING INLOSS OF POWER STEERING ASSIST AND POSSIBLY AN ACCIDENT.

Remedy: REPLACE INCORRECT POWER STEERING HOSES.

Reported: 1988-05-23 (May 23, 1988) · Model years: 1988

CLAMP PLATES USED BETWEEN THE DRIVE SHAFT AND CARRIER YOKES MAY CRACK AND COULD BREAK DUE TO IMPROPER HEAT TREATMENT.

Consequence: IF CLAMP PLATE BREAKS, YOKE WOULD FLY OFF AT DETACHEDPOINT AND COULD INJURY ANYONE STRUCK BY FLYING FRAGMENTS. ALSO, THE DETACHEDINNER SHAFT COULD INTERFERE WITH THE BRAKE SYSTEM AIR SUPPLY HOSES AND TRACTORTIRES, WHICH COULD RESULT IN LOSS OF TRUCK CONTROL AND AN ACCIDENT.

Remedy: INSTALL NEW CLAMPING PLATES AND CAPSCREWS IN ALL LOCATIONS AS NEEDED.

Reported: 1988-07-27 (July 27, 1988) · Model years: 1988

SOME OF THE NUTS/BOLTS USED TO FASTEN THE STEERING PITMAN ARM MAY LOOSEN.

Consequence: THIS WOULD ALLOW THE PITMAN ARM TO COME OFF THE STEERINGGEAR SECTOR SHAFT AND RESULT IN IMMEDIATE LOSS OF STEERING CONTROL AND A VEHICLECRASH COULD OCCUR.

Remedy: RETORQUE NUTS/BOLTS WHERE NECESSARY.

Reported: 1989-05-22 (May 22, 1989) · Model years: 1988, 1989

STEERING WHEEL RETAINING NUTS MAY HAVE BEEN IMPROPERLY INSTALLED AND/OR TORQUED.

Remedy: RENEW AND RETORQUE STEERING WHEEL RETAINING NUTS.