How to Replace Your Idler Pulley

The idler pulley guides the drive belt in your car, maintaining tension as the timing belt rotates at high speeds. If your idler pulley fails and you continue to operate your vehicle, it will likely cause damage to your timing belt too.

However, you can replace your idler pulley quickly if you have the right tools and know how.

Replacement Tips

• Ensure you have parked your car on a flat service.
• Only replace your idler pulley when the engine is cold.
• Every vehicle is different. Check your car handbook for information specific to your model.

Tools You Need

You’ll need the following tools to replace your idler pulley.

• A new idler pulley
• A socket set
• A torque wrench

7 Simple Steps to Replace Your Idler Pulley

Disclaimer: Every vehicle is different. This is a general guide.

Step One

Disconnect the negative battery cable.

Step Two

Loosen the tension adjustment bolt with a socket wrench and remove the drive belt. If your idler pulley is connected to the alternator, you will need to disconnect the entire alternator to relieve the tension on the belt.

On the other hand, if your pulley is connected to the engine block, you will need to loosen the bolt attaching it to the engine block and push the pulley back to release the drive belt. There may also be a protective case around the drive belt that you need to remove.

Step Three

Remove the retaining bolt to release the idler pulley. Hold the pulley so it can’t spin. Loosen the centre bolt with a socket wrench.

Step Four

Compare your old idler pulley with your new pulley to check you have the correct replacement. Then, install the new idler pulley.

Step Five

Once the new idler pulley is in place, tighten the retaining bolt.

Step Six

Use a torque wrench to torque the pulley to the measurement stated in your car handbook. You may also need to use a socket to prevent the pulley from spinning.

Step Seven

Replace any bolts, screws and protective casings that you removed to replace your idler pulley. Reconnect the battery.

Replace Your Idler Pulley

Before you can replace your idler pulley, you’ll need to find the right replacement. DIY Car Service Parts stocks idler pulleys for all makes and models.

Search your number plate in our car lookup tool to see all the tensioners, idler pulleys and dampers that will fit your car.

You can also read our blog posts on:

• Understanding idlers, tensioners and dampers
• How often you should replace idlers, tensioners and dampers
• Signs that your idlers, tensioners and dampers are damaged

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Originally published at https://www.diycarserviceparts.co.uk on June 1, 2020.