Verdict · NHTSA data
Limited data — recalls on file
NHTSA has just 0 complaints on file for the 1975 Mack WS — too few to judge reliability from owner reports alone — but 13 recall campaigns apply to this year, so any used example should have its VIN checked for completed recall work.
0
NHTSA complaints
13
Recalls
0
Investigations
0
Crash-involved
0
Fires reported
0
Injuries
0
Deaths
—
NCAP overall
13 NHTSA recall campaigns on file. Recall repairs are free at franchised dealers.
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.
Defect
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.
Defect
A DESIGN DEFICIENCY EXISTS IN THE AIR DRYER PIPING IN THE AREA OF THE PRESSURE RELIEF VALVE AND COMPRESSOR GOVERNOR CONTROL LINK. MOISTURE IS PASSED AND BUILDS UP IN THIS RELIEF VALVE AND CONTROL LINE. IN FREEZING AMBIENT TEMPERATURES, THIS MOISTURE MAY FREEZE, ALLOWING THE CHASSIS AIR SYSTEM PRESSURE TO EXCEED 150 PSI. EXCESSIVE AIR SYSTEM PRESSURE CAN CAUSE SEPARATION OF AIR PIPING CONNECTIONS AND AIR SYSTEM VALVE FAILURE.
Remedy
THE DEALER WILL RELOCATE THE AIR SYSTEM COMPRESSOR GOVERNOR LINE AND PRESSURE RELIEF VALVE TO ELIMINATE MOISTURE ACCUMULATION.
Defect
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.
Defect
THE LOWER STEERING SHAFT YOKE CLAMP BOLTS ON THE INVOLVED VEHICLES MAY NOT HAVE BEEN SUFFICIENTLY TIGHTENED. SHOULD THESE BOLTS LOSSEN AND COME OFF, THE LOWER STEERING SHAFT COULD SEPARATE FROM THE STEERING GEAR.
Remedy
THE DEALER WILL SECURE THE CLAMP BOLT AND MAKE THE NECESSARY MODIFICATIONS ON THE LOWER STEERING SHAFT, FREE OF CHARGE.
Defect
CRACKS MAY BE PRESENT IN THE BRAKE SPIDER. THESE CRACKS COULD EVENTUALLY CAUSE THE BRAKE SPIDER TO FAIL. THIS COULD ALLOW SEPARATION OF THAT PORTION OF THE BRAKE SPIDER THAT RETAINS THE BRAKE CAMSHAFT, THE BRAKE CHAMBER, AND THE BRAKE CHAMBER BRACKET FROM THE FOUNDATION BRAKE ASSEMBLY. BRAKE PULL IN THE DIRECTION OPPOSITE THE AFFECTED WHEEL LOCATION OR WHEEL LOCK-UP ON THE AFFECTED WHEEL COULD OCCUR.
Remedy
THE DEALER WILL INSPECT AND MODIFY THE AFFECTED BRAKE SPIDERS, FREE OF CHARGE.
The record is thin — 0 NHTSA complaints — so owner-report data can't strongly confirm reliability either way, though 13 recalls should be verified as completed.
Yes — NHTSA lists 13 recall campaigns affecting the 1975 Mack WS. 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.