Diagnosing Engine Belt Noise Video - Pep Boys

Here's a noisy Chrysler 300 with a locked-center tensioned accessory drive. In order to determine if the noise is a chip or a squeal one method is to spray the rib side with water. If the noise gets louder its technically a squeal and therefore a tension issue rather than misalignment.
First disconnect the battery for safety sake. Since this is a locked-center tension drive the adjustable idler pulley should be inspected first. Spin it to check for lock-up, binding or a gravely sound. If it free-wheels the grease is gone. Also check for free-rock. A little is ok but too much means the pulley should be replaced.
Next inspect any remaining pulleys in the drive and replace if defective. If all the pulleys check out or if defective ones have been replaced, the next step is to put a new Dayco belt on the drive and tension it correctly.
The initial tension should be set according to the recommendations of Dayco belt engineers. This six rib belt should be tensioned to 35 pounds per rib or 210 pounds. Use a tension gauge designed for multi-rib belts to test the tension. This first reading is 120 pounds. Continue tensioning and gauging until the correct tension is reached. This belt is now tensioned to the recommended tension of 210 pounds. Remember the number.
ALERT... Pep Boys warn... DO NOT SKIP THE NEXT STEP. It's usually skipped which is the cause of most tensioning problems with serpentine belts on locked-center drives.
Start the engine and run for three to five minutes. This will warm the belt slightly and allow it to seat into the pulleys in the drive. After the running re-check the tension. This belt now registers 150 pounds of tension instead of the initial 210 pounds of tension. After the run-in, the belt should be tensioned to 30 pounds per rib or 180 pounds. Now the belt is correctly tensioned. With correct tensioning the belt can now perform as it was designed to without slipping or belt squeal.
The same run-in and re-tensioning procedure should also be used on V-belt drives. Consult Dayco's fact and data catalog for correct belt tensioning belt data. The previous procedures were for lock-centered tension accessory drives. If squeal occurs in a drive with an automatic tensioner, replacing the tensioner should restore the tension and remedy the noise problem. An accessory drive is a highly engineered precision system of which the serpentine belt is only one element. When belt noise is the problem, the solution may lie with any of the belts elements. Use the procedures to make sure all the elements are functioning correctly. And don't always blame the belt!
Dayco belts are available at your neighborhood Pep Boys Auto Store or find out more online at www.PepBoys.com.
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