Car servicing and repairs | London | TW Motor Inc

Inspect and Adjust Belts

Always Inspect with Engine Off

Belts should be checked on a regular basis (about once a month). In general, you should be on the look out for worn, glazed or frayed belts. Many accessories including the alternator, fan and coolant pump are operated by drive belts. If these belts break or slip the components they drive will fail to work.

 

Here's how to inspect and replace a belt:

 

1.  Twist it so you can see the underside of the "V" shape on V-type belts, or the ribs on a serpentine-type belt. The conditions to look for are cracks that indicate the belt is getting ready to fail. Oil-soaked belts can slip and not rotate the component they are driving fast enough. Glazed belts have a shiny appearance; this occurs when a belt is not tight enough and the slipping polishes its surface. Torn or split belts have major damage and must be replaced immediately.

2.  Before adjusting any drive belt, always check the service manual for specific instructions. Find the longest span in the belt and push on it. It should move in about half an inch. If it moves more than this, the belt is too loose. If it moves less, it is too tight.

3.  Most belts are adjusted by loosening the support for the alternator and moving it back and forth to tighten or loosen the belt. Other systems use an idler pulley for the adjustment.

4.  First loosen the adjustment fastener on the slotted alternator support. Wedge a pry bar between a strong part of the engine and the alternator. Pull on the pry bar to move the alternator housing in a direction to tighten the belt. Tighten the adjustment fastener. Recheck the adjustment by measuring the belt as explained earlier.

5.  When you have determined that a drive belt is defective and needs to be replaced, you should have the replacement belt on hand. Loosen the adjustment fastener on the alternator or idler pulley.

6.  Push the alternator or idler pulley inward to loosen the belt. Pull the old drive belt off the pulleys.

7.  Place the new and old belt side by side on the work bench to make a comparison. The belt width and length of the new belt must be the same. If you find a difference, check to see that you have not gotten the wrong belt. A belt that is too long to be adjusted properly will slip. A belt that is too short will not fit over the pulleys. A belt with the incorrect width or V shape could be thrown off when the engine is running.

8.  Install the correct belt over the pulleys. Adjust the belt to the proper tension as described previously. Start the engine and observe the belt in operation. Stop the engine and recheck the tension.