Idler pulley replacement
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Idler pulley replacement
How much does an idler pulley replacement cost?
The accessories attached to your engine rely on power from the crankshaft to operate.
Utilising drive belts, the energy of the crankshaft revolutions is transferred to these accessories.
But what keeps the belts in check so they don’t fall off? That’s the job of the idler pulley.
It’s main job is to keep the correct tension on the belt from the tensioner, and help guide the belt to stay on the correct routing without coming off.
These idler pulleys rely on bearings to keep them spinning freely and are usually made from plastic, although some models have idler pulleys made from pressed metal or composite materials.
The high temperatures in the engine bay and constant motion on these pulleys can wear them out over time, and the only option is to replace them.
Failure of the idler pulley can cause the drive belt to dislodge from the engine, and this may cause further problems.
These belts drive the alternator, water pump and power steering pump, and overheating and loss of power steering are symptoms that either the belt or one of the pulleys has failed.
Fortunately, idler pulley replacement can be a relatively inexpensive fix, ranging from under $100 to $300 or so, but can be more depending on the type of vehicle you drive.
What is an idler pulley?
An idler pulley is a plastic or metal circular pulley, usually with a roller bearing pressed into the middle.
This is then bolted to the engine via a bracket or stand and the drive belt is fitted securely around it.
The pulley is designed with grooves to correctly mesh with the surface of the drive belt, so that they can ‘grip’ each other to prevent slipping and provide the drive needed to operate the accessories on the engine.
Symptoms of a failing idler pulley
- Battery warning light on dash
- Squealing or screeching noise from the engine
- Engine is overheating
- Loss of power steering
- Burning smell from engine bay
How is an idler pulley replaced?
- The bonnet is opened and the drive belts and idler pulley/s inspected
- The drive belt is removed and the pulleys checked for movement and damage
- The old pulley is removed and a new one fitted
- The drive belt is refitted and lined up correctly
- The engine is operated to ensure correct alignment
Tips to remember
- There is often more than one idler pulley fitted to the engine and if one fails, it’s best to have them all replaced at once to save on labour
- The drive belt should be replaced when replacing idler pulleys to ensure correct operation
Why is it important to have your idler pulley replaced?
Not only is it embarrassing to have your vehicle squealing when you drive, you risk breaking down if the idler pulley can no longer keep tension on the drive belt.
This can happen at any time, without warning, will leave you without power steering and can cause the engine to overheat or the battery to go flat.
It’s best to have your idler pulleys replaced as soon as you notice a problem to ensure your vehicle continues to operate correctly.
