Verdict · NHTSA data
Limited data — recalls on file
NHTSA has just 0 complaints on file for the 1977 Mack RWL — too few to judge reliability from owner reports alone — but 4 recall campaigns apply to this year, so any used example should have its VIN checked for completed recall work.
0
NHTSA complaints
4
Recalls
0
Investigations
0
Crash-involved
0
Fires reported
0
Injuries
0
Deaths
—
NCAP overall
4 NHTSA recall campaigns on file. Recall repairs are free at franchised dealers.
Defect
THE PITMAN ARM RETAINING NUT MAY NOT HAVE BEEN TORQUED TO MANUFACTURER SPECIFICATIONS. THIS COULD RESULT IN INADEQUATE RETENTION OF THE NUT AT THE OUTPUT SHAFT, ALLOWING THE PITMAN ARM TO BECOME LOOSE.
Remedy
DEALER WILL INSPECT AND RETORQUE PITMAN ARM, IF NECESSARY, AT NO COST TO OWNER.
Defect
A SHORT CIRCUIT COULD OCCUR DUE TO CHAFING OR WIRE DISCONNECTION IN THE BOX.
Remedy
THE WIRING IN THE SLEEPER BOX WILL BE CORRECTED, FREE OF CHARGE.
Defect
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 BRAKE SYSTEMS".
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.
Defect
THE POSSIBILITY EXISTS THAT THE ALUMINUM ENGINE REAR SUPPORT BRACKETS MAY FAIL DUE TO METAL FATIGUE. THIS TYPE OF FAILURE WOULD ALLOW THE ENGINE AND TRANSMISSION ASSEMBLY TO DISLOCATE DOWNWARD. THIS WILL RESULT IN THROTTLE CONTROL LOSS WITH THE ENGINE OPERATING CONTINUOUSLY IN THE MID TO UPPER RANGE OF THE GOVERNED SPEED RANGE.
Remedy
DEALER WILL INSPECT AND, IF NECESSARY, REPLACE ALUMINUM SUPPORT BRACKETS WITH BRACKETS MADE FROM DUCTILE IRON FOR INCREASED STRENGTH.
The record is thin — 0 NHTSA complaints — so owner-report data can't strongly confirm reliability either way, though 4 recalls should be verified as completed.
Yes — NHTSA lists 4 recall campaigns affecting the 1977 Mack RWL. Recall repairs are free at franchised dealers; check the VIN at nhtsa.gov/recalls to confirm the work was done.
Based on NHTSA ODI data through June 2026. Complaints are consumer-reported and unverified. Updated July 5, 2026.
Compiled by Sharon Ben-Moshe, Founder.