RecallMyCar

Mack Hmm Recalls & Complaints by Model Year

NHTSA lists 6 safety recalls and 0 owner complaints across 6 model years of the Mack Hmm (1972–1977).

6
safety recalls, all years
0
owner complaints, all years
1976
year with most recalls

Pick your Mack Hmm model year

Model yearRecallsComplaints
1977 Mack Hmm40
1976 Mack Hmm40
1975 Mack Hmm20
1974 Mack Hmm20
1973 Mack Hmm10
1972 Mack Hmm10

All Mack Hmm recalls (6)

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

  1. Service brakes, air: control unit/module

    NHTSA 78V068000 Reported 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

  2. Anchorage (seat belts)

    NHTSA 77V204000 Reported 11 vehicles potentially affected MACK TRUCKS, INCORPORATED

    The involved vehicles do not conform to federal motor vehicle safety standard nos. 207, "seating systems", and 210, "seat belt assembly anchorages". Vehicles equipped with viking t-bar seats have the seat belt anchorage located under the seat. The tether belt ruptured when subjected to the forces required in the safety test.

    Remedy: Dealer will relocate the tether belt floor anchorage to correct the problem, without charge to owner.

    Model years: 1976, 1977

  3. Hanger/bracket (suspension)

    NHTSA 77V205000 Reported 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

  4. Fan (engine and engine cooling)

    NHTSA 77V173000 Reported 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

  5. Anchorage (seat belts)

    NHTSA 77V174000 Reported 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

  6. Universal joint (power train)

    NHTSA 76V118000 Reported 105 vehicles potentially affected MACK TRUCKS, INCORPORATED

    Model years: 1976

Other Mack models

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.