BMW Deflection Pulley - VIACO 11281704500 540i, 740i, 740iL, 840Ci

MFG Numbers 5320144100

Drive Belt Idler Pulley

The drive belt idler pulley works in conjunction with the tensioner pulley/tensioner assembly to maintain tension on the belt as well as guide the belt. Idler pulleys are also used to achieve ideal belt routing around the engine drive accessories such as the power steering pump, water pump, A/C compressor, and alternator.

The idler pulley is an often overlooked maintenance item but it is just as important as the belt tensioner itself. In most cases it is recommended to replace the idler pulley at the same time as the belt tensioner.

Drive Belt Idler Pulley Failure Symptoms

• Visible wear or grooves on pulley
• Belt squealing
• Chirping or grinding sounds coming from pulley bearing
• Odd or uneven belt wear
• Misalignment of pulley when compared to mounting surface