If your belts squeal as you drive or when you start your car, that could be a sign that your idler pulley is worn.
If you notice any squealing, the first place to look is the timing belt, along with the tensioner and the pulleys. Any visible signs of wear could indicate that those parts are worn and need to be replaced.
The idler pulley also contains ball bearings that can grind and squeak as they wear out. These ball bearings can also freeze up. The surface of pulleys made of plastic can also wear down.
The idler’s job is to ensure that the timing belt is aligned and remains on the crankshaft. The engine’s pulley system synchronizes the crank and camshafts, and as these parts wear out, the engine goes out of balance. If this happens, all sorts of odd problems can erupt.
Fortunately, idler and tensioner pulleys are not expensive, averaging between $10 and $30. Likewise, serpentine timing belts are also relatively inexpensive parts.
It’s a relatively easy thing to fix, however, the time it takes for your mechanic to replace these parts could add up to more than an hour. If you are handy with tools and know your way around an engine, you could replace these parts yourself. But, you will need two specialized tools, a torque wrench, and a tensioner pulley wrench. If in doubt, leave this job to your mechanic.
