Mack MH Problems by year

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.

The carrier yoke bolts were manufactured with worn rolling thread dies, causing stress concentrations which caused cracks during the quenching process.

Torque rod bolts are grade 2 instead of grade 5, which is not to specification, and could fail.

Dowels may have been omitted during spring cap installation; this would put shear load on the four (4) spring cap bolts.

Seat tether belt 11.0 Inches long was installed instead of the 8.5 Inches long belt required for this chassis.

Seat tether belts may not have been adjusted during assembly.

THE PITMAN ARM TO DRAG LINK ANGLE IS OUT OF PHASE.

Cross steering levers may be improperly heat treated and subject to fail during normal operation.

On right hand steering arm, keyway may be in the wrong location causing a toggle condition to occur under certain conditions.

Left or right cab step may crack in its welded area due to flexing of the step during entering and exiting. Consequence of defect: as the cracks...

The dual double check valve may not release the proper air volume to the brake system, causing a slight timing delay between the tractor and the trailer brake system...

The drag links may have been installed incorrectly allowing drag link clamp bolt to axle beam interference. Consequence of defect: during a turning...