Belt Tensioner – 4.4 V8 AJ is the automatic tensioner of the accessory (auxiliary) drive belt system, holding the correct running tension on the primary polyvee drive belt.

The assembly combines a spring-loaded pivoting arm with an integral idler pulley, absorbing belt stretch and thermal expansion so that the belt stays seated across the crankshaft and the accessory pulleys throughout the engine speed range. Bearing rumble, belt squeal or visible flutter of the tensioner arm indicate a unit at the end of its service life; it is normally replaced together with the drive belt.

For the 4.4L AJ-V8 petrol engine.