NHTSA Campaign Id 77V173000; Date: Oct. 12, 1977
1972 Mack CF; 1973 Mack CF; 1974 Mack CF; 1975 Mack CF; 1976 Mack CF; 1977 Mack CF; 1972 Mack DM; 1973 Mack DM; 1974 Mack DM; 1975 Mack DM; 1976 Mack DM; 1977 Mack DM; 1972 Mack DMM; 1973 Mack DMM; 1974 Mack DMM; 1975 Mack DMM; 1976 Mack DMM; 1977 Mack DMM; 1972 Mack F; 1973 Mack F; 1974 Mack F; 1975 Mack F; 1976 Mack F; 1977 Mack F; 1972 Mack FL; 1973 Mack FL; 1974 Mack FL; 1975 Mack FL; 1976 Mack FL; 1977 Mack FL; 1972 Mack FS; 1973 Mack FS; 1974 Mack FS; 1975 Mack FS; 1976 Mack FS; 1977 Mack FS; 1972 Mack HMM; 1973 Mack HMM; 1974 Mack HMM; 1975 Mack HMM; 1976 Mack HMM; 1977 Mack HMM; 1972 Mack R; 1973 Mack R; 1974 Mack R; 1975 Mack R; 1976 Mack R; 1977 Mack R; 1972 Mack RD; 1973 Mack RD; 1974 Mack RD; 1975 Mack RD; 1976 Mack RD; 1977 Mack RD; 1972 Mack RL; 1973 Mack RL; 1974 Mack RL; 1975 Mack RL; 1976 Mack RL; 1977 Mack RL; 1972 Mack RM; 1973 Mack RM; 1974 Mack RM; 1975 Mack RM; 1976 Mack RM; 1977 Mack RM; 1972 Mack U; 1973 Mack U; 1974 Mack U; 1975 Mack U; 1976 Mack U; 1977 Mack U; 1972 Mack WL; 1973 Mack WL; 1974 Mack WL; 1975 Mack WL; 1976 Mack WL; 1977 Mack WL; 1972 Mack WS; 1973 Mack WS; 1974 Mack WS; 1975 Mack WS; 1976 Mack WS; 1977 Mack WS
Component: Engine And Engine Cooling:cooling System:fan
Manufactured by: Mack Trucks, Incorporated
Affected Units:: 48,000
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.
Dealer will replace the original fan with a steel fixed blade fan, free of charge.
Vehicle description: trucks equipped with six-cylinder engines. System: engine cooling; fan. Consequences of defect: broken pieces can be propelled outside of the fanshroud and will present an immediate danger and possible injury to personsstanding nearby. Note: prior to correction, vehicle should not be serviced with the hood raisedand the engine running.
Date Owners notified by Manufacturer: Mar 23, 1978
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