Magazine for the auto service professional
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Circle 133 on Reader Service Card What makes the OAD different is a spring inside that absorbs torsional vibrations. Think of it as a "suspension system" for the alternator. It smoothes out the pulses, the speed-ups and slow-downs in belt velocity. As you know, the crankshaft speeds up and slows down between power strokes causing torsional vibration. This condi- tions smoothes out at higher rpms, but is very noticeable at low rpms, especially on smaller engines or engines that feature selective cylinder-kill. The internal torsion spring design is patented by Litens Automotive Group of Toronto, Canada. Replacement OAD pulleys are available from Gates, Veyance (Good- year), Schaeffer (INA) and Advance Auto Parts. As you know they also are available from the automobile dealerships' parts depart- ments, but you may want to compare prices. The aftermarket companies mentioned above sell OEM quality components. Installer beware Beware of counterfeit parts. According to Tendeco, "... a number of global distributors and installers contacted us regarding our 2.0L VW/Audi timing belt tensioner. The complaints have focused around diffculties during installation. All the samples submit- ted were counterfeit parts produced using recognizable brand names as well as the OE logos and part numbers." Also, install only quality remanufactured alternators. The selected OAD must be tuned to the application. Using the wrong replacement will almost certainly result in a comeback. Be suspicious of any rebuilt alternator with a substantially low price. Beware that many times alternators are unnecessarily replaced, when simply replacing the clutch pulley will solve the problem at less expense. In the aftermarket, OAD prices range from about $50 to $120, depending on application. Labor, how- ever, can run from less than a half-hour to Connections