Mack U Recalls & Complaints by Model Year

NHTSA lists 22 safety recalls and 0 owner complaints across 19 model years of the Mack U (1967–1992).

Pick your Mack U model year

• 1967
• 1968
• 1969
• 1970
• 1971
• 1972
• 1973
• 1974
• 1975
• 1976
• 1977
• 1978
• 1979
• 1987
• 1988
• 1989
• 1990
• 1991
• 1992

All Mack U recalls (22)

Every NHTSA safety campaign that lists a Mack U, most recent first, with the model years each one covers.

1. Vehicle speed control

   NHTSA 94V032000 Reported February 15, 1994 39,777 vehicles potentially affected MACK TRUCKS, INCORPORATED

   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.

   Remedy: A new production secondary throttle return system configuration will be installed.

   Model years: 1987, 1988, 1989, 1990, 1991, 1992

2. Linkages (visibility)

   NHTSA 90V051000 Reported March 16, 1990 2,350 vehicles potentially affected MACK TRUCKS, INCORPORATED

   A tolerance mismatch in the crank assembly of the bosch windshield wiper motor could cause instantaneous separation of the crank from the linkage assembly in the left hand control arm assembly; this would make the system inoperable.

   Remedy: Replace left hand control arm linkage assembly.

   Model years: 1989

3. Engine (engine and engine cooling)

   NHTSA 79V133000 Reported May 31, 1979 23,000 vehicles potentially affected MACK TRUCKS, INCORPORATED

   In the event of turbocharger compressor wheel failure, one or more of the four capscrews that hold the turbocharger together may be struck by parts of the compressor wheel, resulting in the capscrews being damaged. If these capscrews are damaged to the point that they allow the compressor back plate to dislocate from the turbocharger…

   Remedy: Dealer will install a shield for the heads of the four capscrews, along with stronger sae 8 grade 8 capscrews, if necessary, at no cost to owner.

   Model years: 1977, 1978, 1979

4. Steering wheel/handle bar (steering)

   NHTSA 79V082000 Reported April 3, 1979 12,000 vehicles potentially affected MACK TRUCKS, INCORPORATED

   An improper pinch bolt and nut may have been used in the clamping of the steering shaft to the steering gear input shaft. Due to clamping force loads applied at the bolt, the nut could yield, resulting in looseness of the input shaft yoke. Should this condition go unnoticed, spline wear could cause shaft separation.

   Remedy: Vehicles will be inspected and, if necessary, the correct fasteners will be installed at no charge to owner.

   Model years: 1977, 1978

5. Multiple axle (suspension)

   NHTSA 79V017000 Reported January 12, 1979 4,000 vehicles potentially affected MACK TRUCKS, INCORPORATED

   A casting deficiency exists in the lower section of the caps resulting in a reduction in the thickness of the material. Failure of a cap can allow the end of the rear spring to detach from the axle housing.

   Remedy: Dealer will inspect and, if necessary, replace any of the spring insulator caps found to be defective. This will be done at no cost to owner.

   Model years: 1977, 1978

6. Interconnecting assembly(wiring) (service brakes)

   NHTSA 78V210000 Reported October 3, 1978 19,370 vehicles potentially affected MACK TRUCKS, INCORPORATED

   Delays of up to about 2 seconds may exist in the brake application times to the brakes on the bogie axles in the presence of certain types of wheel speed sensor signal discontinuities or distortions that may occur as a result of sensor wire failure. This constitutes a non-compliance to federal motor vehicle safety standard no. 121, "air…

   Remedy: Dealer will install new wheel speed sensors that incorporate improved wiring and the present bogie anti-wheel lock system will be changed to an axle-to-axle system for improved reliability.

   Model years: 1977, 1978

7. Arm (steering)

   NHTSA 78V171000 Reported August 8, 1978 2,100 vehicles potentially affected MACK TRUCKS, INCORPORATED

   Deficiencies, in the form of forging laps, cracks and excessive decarburization during heat treatment, exist in the steering knuckles. Stresses imposed with integral hydraulic power steering may lead to a failure in the area of the steering arm attaching boss. This type of failure would cause loss of steering control.

   Remedy: Dealer will inspect and, if necessary, replace the left steering knuckle with an improved type of knuckle.

   Model years: 1971, 1972, 1973, 1974

8. Service brakes, air: control unit/module

   NHTSA 78V068000 Reported April 4, 1978 9,700 vehicles potentially affected MACK TRUCKS, INCORPORATED

   An axle "no brake" condition could result from an eaton controller internal electrical malfunction. This condition may cause the anti-wheel lock valve solenoid to be continuously energized and prevent the brakes from being applied on one of the axles. As a result, the anti-wheel lock warning lamp is not activated.

   Remedy: The dealer will inspect and, if necessary, replace the anti-wheel lock controller without charge to owner.

   Model years: 1974, 1975, 1976

9. Multiple axle (suspension)

   NHTSA 78V031000 Reported February 9, 1978 33,000 vehicles potentially affected MACK TRUCKS, INCORPORATED

   The tee bracket, which is mounted on the front axle of the bogie, may fail due to vibration brought on by road surface irregularities. Bracket failure would leave the tee bracket unsupported and cause broken hose connector fittings. This would result in automatic application of the spring emergency brakes.

   Remedy: The dealer will replace the defective bracket with a redesigned version.

   Model years: 1975, 1976, 1977, 1978

10. Hanger/bracket (suspension)

    NHTSA 77V205000 Reported November 21, 1977 7,400 vehicles potentially affected MACK TRUCKS, INCORPORATED

    A deficiency exists in the welds securing the rear spring insulator bracket to the axle housing. This is due to improper positioning of the weld, in relationship to the bracket and axle housing. Failure of the welds would cause separation of the spring insulator bracket and the axle housing, resulting in improper alignment of the…

    Remedy: Dealer will reweld the insulator spring bracket at no cost to owner.

    Model years: 1977

11. Fan (engine and engine cooling)

    NHTSA 77V173000 Reported October 12, 1977 48,000 vehicles potentially affected MACK TRUCKS, INCORPORATED

    The flex blade fans on the involved vehicles may develop cracks in the laminated stiffener as a result of fatigue during operation. If such a condition exists and the cracks go undetected, continued operation could cause pieces of the stiffener to break off.

    Remedy: Dealer will replace the original fan with a steel fixed blade fan, free of charge.

    Model years: 1972, 1973, 1974, 1975, 1976, 1977

12. Anchorage (seat belts)

    NHTSA 77V174000 Reported October 12, 1977 6,591 vehicles potentially affected MACK TRUCKS, INCORPORATED

    The involved vehicles do not conform to federal motor vehicle safety standard no. 209, "seatbelt assemblies". Although the seatbelts in question performed marginally with respect to the 5000 lb. Load requirement, additional testing confirmed that the anchor could fail, allowing either the anchor to slip over the hold-down nut or the…

    Remedy: Dealer will inspect and, if necessary, replace seat belt assemblies without charge to owner.

    Model years: 1977

13. Leaf (suspension)

    NHTSA 76V004000 Reported January 13, 1976 54 vehicles potentially affected MACK TRUCKS, INCORPORATED

    Model years: 1975

14. Interconnecting assembly(wiring) (service brakes)

    NHTSA 75V190000 Reported October 31, 1975 3,400 vehicles potentially affected MACK TRUCKS, INCORPORATED

    Model years: 1974, 1975

15. Hoses, lines/piping, and fittings (service brakes)

    NHTSA 75V192000 Reported October 31, 1975 1,200 vehicles potentially affected MACK TRUCKS, INCORPORATED

    Model years: 1974, 1975

16. Multiple axle (suspension)

    NHTSA 75V118000 Reported June 23, 1975 414 vehicles potentially affected MACK TRUCKS, INCORPORATED

    Model years: 1967, 1968, 1969, 1970, 1971, 1972, 1973

17. Suspension

    NHTSA 74V001000 Reported December 2, 1974 1,119 vehicles potentially affected MACK TRUCKS, INCORPORATED

    Model years: 1973

18. Switch (exterior lighting)

    NHTSA 74V227000 Reported November 21, 1974 1,023 vehicles potentially affected MACK TRUCKS, INCORPORATED

    Model years: 1973, 1974

19. Banjo housing (power train)

    NHTSA 74V032000 Reported February 25, 1974 9,019 vehicles potentially affected MACK TRUCKS, INCORPORATED

    Model years: 1971, 1972

20. Fuel injection system (fuel system)

    NHTSA 72V127000 Reported May 22, 1972 1,410 vehicles potentially affected MACK TRUCKS, INCORPORATED

    Model years: 1970, 1971

21. Linkages (steering)

    NHTSA 72V041000 Reported February 14, 1972 538 vehicles potentially affected MACK TRUCKS, INCORPORATED

    Model years: 1970, 1971

22. Electrical heating element (visibility)

    NHTSA 69V109000 Reported August 13, 1969 87 vehicles potentially affected MACK TRUCKS, INCORPORATED

    Model years: 1969

Other Mack models

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• Ch6 complaints
• Gu6 complaints
• CH6005 complaints
• Cxu5 complaints

Source: NHTSA recall and complaint databases and EPA fuel economy data, October 2026. Complaint counts are owner reports to NHTSA, not verified defects. Recall counts are safety campaigns that list this model year; whether a particular car was already repaired depends on its VIN. How this data is compiled.