Cooling & lubrication

Accessory drive belt

Transfers engine rotation to belt-driven accessories.

Where it sits

At the engine’s accessory drive end.

How it works

A tensioned ribbed belt follows pulleys for the accessories present on that engine.

Think of it as

A conveyor linking several pulleys.

Symptoms when it fails

Squeal, fraying or charging faults may arise from belt, tensioner, pulley or accessory issues.

Lifespan

Fluids use vehicle-specific schedules. Seals, pumps and heat exchangers depend on age, condition and operating history.

Repair cost

Simple seals and filters can be accessible; an integrated pump, buried housing or overheating damage can make repairs more involved.

The BMW angle

A BMW accessory belt and its internal timing chain do different jobs.

Used in

BMW combustion models; additional coolant circuits also appear in hybrids and electric BMWs.

Sources
Same system

Cooling & lubrication