2005–2007 Mack CHN, 2008 Mack Chu, 2006 Mack CTP and 4 other models Recall: ON CERTAIN TRUCKS EQUIPPED WITH PARKER SINGLE CHECK VALVES (SCV) PROVIDED…

The defect

ON CERTAIN TRUCKS EQUIPPED WITH PARKER SINGLE CHECK VALVES (SCV) PROVIDED BY BENDIX. THE DEFECT EXISTS IN THE PARKER SCV THAT CONNECTS WITH THE SUPPLY PORT OF THE SR-7 SPRING BRAKE MODULATING VALVE. AFTER PROLONGED USE OF THE PARKER SCV, THE VALVE BODY RETAINER MAY BECOME EXCESSIVELY WORN AND EVENTUALLY BREAK APART. PIECES OF THE PARKER SCV CAN BECOME LODGED INSIDE THE SR-7 SPRING BRAKE MODULATING VALVE, POTENTIALLY CAUSING EITHER LEAKAGE OUT OF THE SR-7 VALVE OR PREVENTING AIR FROM PROPERLY EXHAUSTING FROM THE SR-7 VALVE.

The risk

THIS CONDITION CAN CAUSE A DELAY IN THE APPLICATION OF THE SPRING BRAKES TO PARK THE VEHICLE AFTER THE OPERATOR PULLS THE DASH VALVE BUTTON. THESE CONDITIONS CAN OCCUR WITHOUT WARNING, LEADING TO UNINTENDED VEHICLE ROLLAWAY, BRAKE DRAG, OR IN THE CASE OF LOSS OF PRIMARY CIRCUIT, INABILITY TO MODULATE THE SPRING BRAKES.

The fix — what to do

MACK IS WORKING WITH BENDIX TO REPLACE THE PARKER SINGLE CHECK VALVE. THE RECALL BEGAN ON JANUARY 9, 2008. OWNERS MAY CONTACT BENDIX AT 1-440-329-9000 OR MACK AT 1-800-528-6586.

MACK RECALL NO. SC0334 (SC0327).CUSTOMERS MAY CONTACT THE NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION'S VEHICLE SAFETY HOTLINE AT 1-888-327-4236 (TTY: 1-800-424-9153); OR GO TO HTTP://WWW.SAFERCAR.GOV.