The serpentine belt was first used in 1985 on a Mercedes 190. This new belt took the place of multiple accessory drive belts, making it much easier to replace. The advantages are numerous. A serpentine belt supplies more tension on the pulleys, and by virtue of its width, it all but eliminates slippage. This allows the use of underdrive pulleys, which free up significant horsepower. The serpentine belt will also display advance warning of immanent failure, unlike V-belts. The serpentine belt tensioner consists of a round spring housing, approximately 4 inches in diameter, mounted to the engine block. From this housing a lever or arm extends with a round pulley. The spring supplies ever-increasing tension as the arm is lifted. This tensioner applies spring tension against the belt with enough arm movement to keep the tension constant.
Instructions
- 1
Grasp the belt in the center between the tensioner and the next pulley. Pull and push on the belt while observing the tensioner for free, unhindered movement.
2Place a wrench on the bolt in the pulley, and push the tensioner away from the belt. Remove the belt from the tensioner pulley only. While pushing on the tensioner, pay attention to the amount of effort needed to oppose the spring tension. It should be significant, and the movement of the tensioner arm must be smooth.
3Inspect the round spring housing for damaged or missing plastic covers. A white plastic cover separates the spring from the arm. If the plastic wears out, it gets entangled in the spring and causes resistance to the arm's movement.
4Inspect the pulley itself. If there is heavy grooving, which is usually the case if the pulley is the original plastic type, replace the pulley by itself if no other problems are present.
5Spin the pulley by hand and feel for a grinding in the bearing indicating a worn bearing. Replace the pulley if this is present.
