Most cars built in the last 25 years have a long serpentine belt that drives the alternator, power steering pump, air conditioner, and other engine accessories. A spring loaded belt tensioner pulley holds the serpentine belt at the correct tightness. The belt manufacturers (ACDelco, Dayco, Gates, Goodyear, etc.) strongly recommend replacing the belt tensioner when the belt is replaced. Some of the belt manufacturers also manufacture belt tensioners, but their urgings to replace tensioners are not just an effort to sell more parts. They are concerned about the reputation of their belts and warranty claims when a worn out tensioner causes damage to a new belt and or engine accessories.
With my own cars, I must admit I have not always been replacing the belt tensioner every time I replace the serpentine belt. The tensioner often costs more than the belt and my really old cars with V-belts have done just fine without any fancy fine-tuning of the belt tension.
I need to pull my head out of the 1970s. Cars now often last beyond 200,000 miles, serpentine belts must often drive a half dozen accessories while winding through a series of contortions, and perhaps most importantly, engine accessories are not as cheap as they used to be. An alternator for my 1979 Chrysler 300 is around $25 (at RockAuto). Alternators for “newer” cars like my wife’s 1993 Ford Tempo are typically $100 and up, sometimes way up. The Tempo’s original AC compressor still works fine and is filled with very expensive Freon. That compressor and its bearing alone are worth protecting.
Last weekend I followed through on my new years resolution to replace the serpentine belt on my wife’s Tempo before another month passed. The belt tensioner had over 90,000 miles (145,000 km) on it so I remembered to replace that too. The old belt tensioner (in photo next to the new one) did not make any noise and it did not visibly vibrate. Off the car, the cover over the tensioner’s spring popped open a bit and I could feel some wiggle in the pulley bearing. Maybe it could have lasted longer or maybe it and the new belt would have put too much or too little tension on one of the engine accessories. The new belt tensioner and the thirty seconds it took me to bolt it on bought me peace of mind. I do not have to imagine trying to explain to my wife why the new belt squeals, why it fell off, or why I need to spend a day replacing the new belt and a leaky water pump or some other failed engine accessory. My wife can immediately recognize when I am feeling guilty and I would hate to lose my position as her main Tempo mechanic!
Last weekend I followed through on my new years resolution to replace the serpentine belt on my wife’s Tempo before another month passed. The belt tensioner had over 90,000 miles (145,000 km) on it so I remembered to replace that too. The old belt tensioner (in photo next to the new one) did not make any noise and it did not visibly vibrate. Off the car, the cover over the tensioner’s spring popped open a bit and I could feel some wiggle in the pulley bearing. Maybe it could have lasted longer or maybe it and the new belt would have put too much or too little tension on one of the engine accessories. The new belt tensioner and the thirty seconds it took me to bolt it on bought me peace of mind. I do not have to imagine trying to explain to my wife why the new belt squeals, why it fell off, or why I need to spend a day replacing the new belt and a leaky water pump or some other failed engine accessory. My wife can immediately recognize when I am feeling guilty and I would hate to lose my position as her main Tempo mechanic!
Tom, RockAuto.com
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