2008 Volvo S40 Timing Belt Idler Pulley Replacement Cost

To properly route the timing belt to necessary components, the timing belt idler pulley is used. The idler pulley is a metal wheel with a smooth exterior, and serves no other purpose but to hold the timing belt in place as it drives the timing gears.

The idler pulley is bolted through the center into the engine, and the smooth side of the timing belt turns the pulley to reduce friction and heat.

If the idler pulley fails, there will be a very audible chirping noise from the front of the engine. This is because the idler pulley bearing is no longer smooth. If it is not changed immediately, the engine will being running roughly, or stall completely, and internal engine damage may occur due to slippage or breakage of the timing belt. The check engine light will illuminate on the dashboard in the event of total failure, and OBD trouble codes for misfires, crankshaft position, and camshaft position will be stored.

It is not recommended to drive a vehicle suspected of idler pulley bearing failure. This can quickly result in complete engine failure as described above.

Timing belt idler pulleys are replaced during a timing belt replacement service, either as preventive maintenance or due to suspected failure. This means the average idler pulley replacement occurs between 60,000 and 105,000 miles, depending on the manufacturer specified timing belt service interval.