V-Belt
A V-belt is a drive belt with a V-shaped cross-section that turns auxiliary units such as the alternator, water pump and power steering pump from the crankshaft pulley.
Prepared by the Bicops Technical Content Team · Last updated:
Shop V-BeltWhat does it do?
It transfers the rotation the engine produces to the auxiliary units. If the belt goes slack it slips in the pulley groove: the alternator cannot produce enough charge, the water pump cannot circulate coolant properly and the engine overheats. The V cross-section is designed to wedge into the pulley groove and increase the friction area.
Fault symptoms
A squeal heard on cold start or when the steering is turned to full lock is the best-known sign that the belt is slipping in the pulley. Cracks on the surface, a burnt rubber smell, fraying at the edges and rubber dust around the pulley call for replacement. An intermittent battery light on the dashboard can also point to a slack belt.
Selection and tension
V-belts are chosen by profile and length; the wrong length makes correct tensioning impossible. Confirming the size your car uses from the OEM number is the safest route. When fitting, tension must be set to the manufacturer’s value: a slack belt slips and squeals, an over-tightened belt wears out the alternator and water pump bearings.
Frequently Asked Questions
How often is a V-belt replaced?
The general interval is 40,000-60,000 km or 4 years. If a visual check shows cracks or fraying, do not wait for the mileage.
Is belt spray a correct fix for squealing?
Belt sprays mask the noise temporarily but do not cure slackness or wear; the belt keeps slipping, so overheating and charging problems continue.
Can I keep driving if the V-belt snaps?
If the belt drives the water pump, the engine overheats quickly and continuing causes severe engine damage. Charging also stops, so the car will stall shortly afterwards.