5 Symptoms of a Bad Crankshaft Pulley (and Replacement Cost)

With so many working parts in and around the engine, it can sometimes be difficult to determine which part is malfunctioning, as many symptoms relate to multiple components. This is the case when you have a faulty crankshaft pulley or a faulty crankshaft harmonic balancer.

We review the signs of a bad crankshaft pulley, its location, function, and replacement cost. Here’s a quick overview of the signs to look for:

The most common symptoms of a bad crankshaft pulley are engine vibration and rough engine idling. It can also lead to a damaged alternator, power steering pump, or faulty transmission if you’re unlucky.

Here is a more detailed list of the symptoms of a bad crankshaft pulley:

Symptoms of Bad Crankshaft Harmonic Balancer

1. Engine vibration

The car vibrates at idle

The most prominent symptom that indicates something is wrong with the crankshaft pulley is engine vibration. This will be the first sign you notice, as long as you are careful.

The crankshaft pulley is usually equipped with a harmonic balancer. This component absorbs engine vibrations, allowing you to accelerate smoothly. However, when the balancer fails, the vibrations are no longer absorbed.

This fault causes noticeable shaking that gets worse as it progresses.

2. Engine idling rough

As you sit in your parked vehicle, you become familiar with the sound of slow motion. When something seems wrong, it could be related to the crankshaft pulley.

Erratic engine speeds are common with a bad crankshaft pulley because the damper is under more pressure, especially at idle. You may notice that the engine’s RPM fluctuates everywhere.

3. Dead alternator

While the alternator charges the battery and runs the accessories, the crankshaft pulley is responsible for powering this component. If the crankshaft pulley fails, the alternator no longer spins and produces power.

You will notice signs that resemble a dead car battery. The lights may flicker and you will not be able to start the vehicle for a long time because the battery cannot be charged.

RELATED: 8 Causes of Your Car Battery Light Coming On While Driving

4. Power steering pump failure

Table Mounted Power Steering Pump

The car’s power steering pump also works with the crankshaft pulley. This critical component pumps hydraulic fluid through the system to keep the steering working as it should.

When power steering fails, it will take much more effort to control your vehicle. You may think the system is low on fluid, but a simple check will show that this is not the case.

5. Damaged transmission or internal engine parts

If you allow engine vibrations to occur for a long time, damage to the transmission or internal motor will occur. This can wear out the crankshaft bearings if you’re unlucky, and your car’s transmission has many parts that aren’t designed to withstand these types of vibrations. The gears, input shaft and bearings are susceptible to damage.

When the transmission starts to fail, you may notice shifting problems, whistling, and fluid leaks. It’s not something you want to deal with just because you had a bad crankshaft pulley.

Crankshaft pulley function

The car engine works on the power given by the fuel. This power is then transmitted to other components through the use of various electrical and mechanical systems. One of these mechanical systems is the crankshaft pulley, which is responsible for power distribution.

The crankshaft pulley drives all components connected to the crankshaft. While the crankshaft drives the car’s wheels, the pulley transmits power to other parts, such as the alternator and power steering pump.

The crankshaft pulley includes an internal damper, responsible for decreasing vibration along the pulley belts. If left uncontrolled, these vibrations can damage connected systems.

While a broken or defective crankshaft pulley belt is easy to replace, a broken shock absorber requires the replacement of the crankshaft pulley.

So what causes a crankshaft pulley to malfunction? Although the part is designed to last the life of your engine, it can easily fail. Most models have a rubber insulation ring that breaks down when exposed to high temperatures, which is a natural occurrence in the engine. Additionally, if there is a coolant or oil leak entering the pulley, it can contaminate it and accelerate its deterioration.

Crankshaft pulley location

The crankshaft pulley, also known as the harmonic balancer, is located at the end of the crankshaft. It is a wheel-like device with grooves that connect directly to the crankshaft.

While the crankshaft is responsible for converting straight or linear motion to the pistons, the crankshaft pulley connects to various other components through the use of accessory belts.

Crankshaft pulley replacement cost

The cost to replace the crankshaft pulley ranges from $350 to $400, depending on the car model and labor costs. You could spend between $200 and $240 on a new crankshaft pulley, plus about $150 in labor.

If you purchase an aftermarket crankshaft pulley, you can save some money. Plus, luxury cars can cost a little more overall.

If you would like to replace the crankshaft pulley yourself, the job is not that complicated.

  1. Remove all engine drive belts.
  2. Remove the crankshaft pulley bolt. You will need a pulley bracket and a high torque impact wrench.
  3. Remove the old pulley.
  4. Install the new crankshaft pulley.
  5. Replace the bolt and tighten it.
  6. Reinstall all engine drive belts.


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