Mack MR Brake problems by year

Mack is recalling 218 my 2006-2007 mr trucks. A check valve was omitted from the secondary supply port of the sr-7 spring brake modulating valve.

On certain trucks equipped with bendix sr-7 spring brake modulating valves, the internal rubber check valve may leak causing a delay in the application of the spring brakes to park the vehicle after the operator pulls the dash valve button.

On certain trucks equipped with sr-7 bendix brake valves, the check valve inside the valve cavity may not properly set, causing internal air leakage. If the check valve does not properly seat, the resulting leakage can cause a delay in the application of the...

On certain class 8 chassis built with hendrickson lift axles which contained webb brake drums, the brake drums could experience premature crack of the braking surface resulting in reduction or complete loss of braking on that wheel end or loss of brake drum...

Certain heavy duty vehicles fail to comply with the requirements of federal motor vehicle safety standard no. 121, "Air brake systems." Improper seating of the check valve retainer in the brass fitting housing has occurred. It is possible for the air brake...

Vehicle description: heavy duty trucks equipped with certain meritor-wabco brake system two and four port relay valves. The valve may stick open when a high-pressure application is released.

Vehicle description: heavy duty trucks built with bendix air abs with an ec-17 1030r electronic control unit (ecu), there have been reports of unwanted abs activation at low speeds caused by 1) chafed abs wheel speed sensor wires on rotating parts or 2) a...

Air system blockage in the air dryer occurs degrading the moisture removing capabilities of the dryer when the vehicle is operated in a cold environment and moisture accumulates and freezes in the air dryer or in the line between the dryer and the air system...