Cooling System
Accessory Belt Idler Pulley
An accessory belt idler pulley guides the serpentine belt around the engine and keeps it on its correct path. We carry 144 idler pulleys and belt drive kits from $6 to $217 for 1989-2019 vehicles. Gates and Dayco make most of them, with wide coverage for Chevrolet models plus the Dodge Dakota and Ram 2500.
Shop accessory belt idler pulley by vehicle
ContiTech Accessory Drive Serpentine Belt Drive Component Kit ADK0033P
Fits 2007 models
AC Delco Serpentine Belt Drive Component Kit ACK060935HD for Chevrolet Silverado 1500
Fits 2013 models
AC Delco Air Conditioning Serpentine Belt Drive Component Kit ACK040378HD
Fits 2008 models
Signs of a worn idler
An idler pulley spins freely on a sealed bearing and does not drive anything. It routes the belt so it wraps far enough around the other pulleys.
As the bearing wears, you may hear a squeal, chirp or grinding noise from the front of the engine, often worse on a cold start. With the belt off, a bad idler feels rough, wobbles or makes noise when you spin it by hand. Uneven belt wear or a belt that jumps off can also point to the idler.
Grooved, smooth and kits
Idlers that ride on the ribbed side of the belt are grooved. Those on the flat back side are smooth. Our listings name positions such as main drive, upper, above water pump, air conditioning and AC bypass, so match yours to the right spot.
Many listings are complete serpentine belt drive kits with a belt, tensioner and one or two idlers. These suit high mileage engines where every part has the same wear. Some pulleys come with a bolt, insert and dust shield.
Fitment and install tips
Take a photo of the belt routing or find the diagram under the hood before you remove anything. Release tension with a breaker bar or belt tool on the tensioner.
Pick your vehicle and read the fitment table for engine size and AC option, since the same model can use different idlers. Compare the pulley diameter and width with the old one. Torque the bolt to spec and spin the engine by hand to check belt tracking.
Accessory Belt Idler Pulley questions
How do I know if it is the idler or the tensioner making noise?
Remove the belt and spin each pulley by hand. A rough, noisy or wobbly pulley is the one at fault. A tensioner arm that bounces or has weak spring force needs replacing too.
Should I replace the belt with the idler pulley?
It is a good idea if the belt is cracked, glazed or has high mileage. A belt drive kit covers the belt, tensioner and idler in one order.
What is the difference between a grooved and a smooth idler pulley?
A grooved pulley has ribs that match the belt's ribbed side. A smooth pulley runs on the flat back of the belt. Each position needs the correct type.