The 1977 Mack Hmm has 4 NHTSA recall campaigns affecting an estimated 62,002 vehicles. Recall repairs are always free at any authorized dealer. Last updated July 5, 2026.
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…
DEALER WILL REWELD THE INSULATOR SPRING BRACKET AT NO COST TO OWNER.
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…
DEALER WILL RELOCATE THE TETHER BELT FLOOR ANCHORAGE TO CORRECT THE PROBLEM, WITHOUT CHARGE TO OWNER.
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…
DEALER WILL INSPECT AND, IF NECESSARY, REPLACE SEAT BELT ASSEMBLIES WITHOUT CHARGE TO OWNER.
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.
DEALER WILL REPLACE THE ORIGINAL FAN WITH A STEEL FIXED BLADE FAN, FREE OF CHARGE.
Recall, complaint, and investigation records from official NHTSA datasets (FLAT_RCL, FLAT_CMPL, FLAT_INV), synced weekly. Counts reflect NHTSA records for the 1977 Mack Hmm as of July 5, 2026. Complaint narratives are consumer-submitted and unverified. This page contains ads and affiliate links. Full methodology.