What is an Idler Pulley?

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What the heck’s an Idler Pulley and what does it do? And how do I fix one on my car?

These are all important questions we will answer in this article.

An idler pulley is a very specialized kind of pulley in an automobile and it’s purpose varies based on the position where it’s used.

Ready to learn more about idler pulleys? Then read on.

What is an idler pulley?

Idler pulleys are tiny wheels attached to a shaft that helps to direct the path of the transmission drive belt and reduce its vibration.

They are usually found on the front of the engine, just behind the crankshaft pulley. In some cases, they are also attached directly below the crankshaft itself.

You may also find idler pulleys near the water pump, air conditioner, power steering pump, and alternator.

What is an idler pulley made from?

The idler pulley is typically a small diameter, smooth-surfaced wheel that is used to guide the transmission drive belt.

It is usually made of metal or plastic and has bearings inside so it can roll easily as the belt moves over it.

How does an idler pulley work?

The idler pulley plays an important role in how well your car’s engine performs.

It reduces friction between the drive belt and any other part of the engine that moves while providing support and balance to the belt itself.

A typical idler pulley is nothing more than a wheel with a shaft attached to it.

The shaft is usually made of steel, which is strong enough to withstand the stress caused by the engine’s moving parts.

Attached to this steel bar is a wheel, which is made out of a smooth material. This wheel can be as small as two inches wide or as large as six inches wide, but it is always round and smooth so that it can spin freely on its axis when the drive belt moves over it.

Idler pulleys serve one important purpose: keeping your car’s engine running smoothly by reducing vibrations.

As you drive, your engine shifts gears and changes speed many times per second. These shifts cause vibrations in all areas of your car’s engine, including any parts that move with each gear shift.

Fixed vs adjustable

There are two main types of idler pulleys: fixed and adjustable.

Fixed idler pulleys consist of two pieces – a wheel and a bracket.

On the other hand, adjustable pulleys have just one wheel. The wheel can be moved up or down on its axis by loosening (or tightening) the bolt that holds it in place. This allows you to adjust the ratio between engine RPMs (revolutions per minute) and wheel speed so that your vehicle’s drivetrain operates at optimum efficiency.

When are idler pulleys replaced?

The idler pulley plays an important role in how well your car’s engine performs.

It reduces friction between the drive belt and any other part of the engine that moves while providing support and balance to the belt itself.

As the belt moves over the grooves of the idler pulley, it is pushed into contact with any other moving parts such as crankshaft pulleys, camshaft pulleys or air conditioning compressor pulleys, keeping the engine running smoothly.

Idler pulleys are often replaced when inspecting a broken serpentine belt or when replacing one due to age or wear.

When idler pulleys wear down or break, they can cause damage to other parts of your car’s engine. For instance, if an idler pulley breaks completely, it can cause damage to your serpentine belt.

If you suspect that you have an idler pulley problem, there are several signs that indicate that it may be time for an inspection and possible replacement.

Symptoms of a failing or bad idler pulley

A loose or dropped drive belt, noises from bearings, or a damaged drive belt are all potential signs of idler pulley failure.

If you have a problem with your idler pulley, it may be obvious from the sound emanating from under your hood.

If you hear a high-pitched squeaking or squealing noise when you accelerate, a worn idler pulley may be to blame.

If you hear grinding or clunking noises coming from your engine area when you start your car, that could also be indicative of an idler pulley problem.

A rattling noise coming from under your hood may mean there is an unsecured component on your idler assembly that is loose and needs to be tightened or replaced.

How do you install a new idler pulley?

Midia car

If you have the right tools and mechanical knowledge, replacing an Idler pulley shouldn’t take too long.

Before replacing the idler pulley, you need to have a few tools handy. First, you will need a jack and jack stand.

You will also need a torque wrench, a socket extension, and a socket set with the appropriate size for your car (usually 19mm or 21mm). Finally, you will want to have a flat head screwdriver and a pair of pliers.

The process involves disconnecting the battery, removing the drive belt, replacing the pulley, and adjusting the torque of the pulley.

Check out this detailed guide for a full set of instructions.

How much does it cost to replace an idler pulley?

Fixing an idler pulley in Australia is one of the more affordable processes that will be completed by your mechanic. This is because the process is fairly straightforward, as outlined above.

Expect to pay anywhere from $200 to $400 for idler pulley replacement.

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Mike Jarvis

Mike is an automotive writer with a life-long passion for all things with four wheels.