Adjusting belt tension

| July 01, 2009

To adjust belts that are tensioned with bolted brackets, rather than an automatic tensioner, it’s best to use a tension gauge, which is calibrated in pounds. Follow these steps:

· Loosen the mounting bolts that hold the alternator, A/C compressor or fan hub in place.
· Depress a knob on the gauge and assemble it around the belt, with the two stationary prongs on the inside of the belt and the movable one on the outside.
· Release the knob. The dial will rotate and show the tension in pounds.
· Turn the adjusting bolt one way or the other to increase or reduce tension in accord with the tension listed in the gauge guide or in your engine owner’s manual.
· Once tension is correct, tighten the attaching bolts and recheck.
If testing with your thumb, you should be able to depress the belt no more than its thickness in a short span, one foot or less, or no more than twice its thickness in a span of two feet or more.

With a standard V-belt tensioned with bolted brackets, set the tension at the maximum recommended for a new belt. After about 3,000 miles, the belt may stretch slightly, so recheck tension.

Before removing a serpentine belt to install a new one, note its routing around the crankshaft, various accessories and the automatic tensioner. To remove the old belt, rotate the tensioner to reduce tension.

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