Harmonic Balancer (Everything To know)

Although harmonic balancers are an essential component of any engine build, what exactly do they do? Is it necessary to have one? Is a bigger harmonic balancer better?

In this article, we discuss everything you need to know about the harmonic balancer, what it does, what happens when it fails, how you can go about replacing it and so much more.

What Is A Harmonic Balancer?

Harmonic balancers are additional drive components located at the front of the engine and connected to the crankshaft. Their main function is to reduce engine vibration and, in some cases, act as pulleys for drive belts.

Harmonic balancers are known by many names, such as crankshaft pulleys, dampers, and crankshaft balancers.

What Does A Harmonic Balancer Do?

Harmonic balancers are primarily designed to absorb vibrations from the crankshaft.

A four-stroke engine performs four strokes: intake, compression, power, and exhaust, and each piston in the engine performs a stroke as well during those four strokes. The crankshaft is turned by the movement of the pistons and their involvement in these four cyclic operations.

During the compression stroke of a four-stroke engine, other pistons move higher and push down on the vertical shaft of the crankshaft, which decreases the speed of rotation.

The crankshaft is subject to mechanical resonance through opposing forces, which could lead to a risky resonance phenomenon.

Harmonic balancers minimize high-frequency vibrations produced by the crankshaft. They are usually made up of a center hub, an insulator, and also an inertia ring.

In some designs, viscous fluid is also used. The crankshaft’s center hub is tightly bolted to the end. Turns and vibrations are absorbed by the rubber ring and inertia rings of the crankshaft.

The harmonic balancer creates a bolted-on or integral pulley that operates with the drive belt when an engine is running.

The pulley rotates due to engine power which turns the accessories driven by it such as the alternator, air conditioning compressor, and other engine-driven components.

What happens When A Harmonic Balancer Gets Bad?

bad Harmonic Balancer

Harmonic balances may seem basic, but they are quite complex parts. It helps reduce vibrations in the crankshaft by using balancing weights and/or dampers.

A faulty harmonic balancer incapable of dampening the crankshaft vibrations can result in a damaged crankshaft or the wear and tear of the engine’s bearings.

A bad Harmonic balancer could damage engine-driven accessories and the belt. A bad Harmonic balancer may fly apart, which may destroy several parts beneath the hood.

We recommend replacing a bad harmonic balancer as soon as possible.

Bad Hamonic Balancer Symptoms

The harmonic balancer, also known as a crankshaft damper or vibration damper, is an automotive component that is often overlooked. Although it is easy to forget about, it can cause severe engine damage if it fails.

If your harmonic balancer is bad, you may experience one or more of the following symptoms.

1. Vibrations in the engine

Harmonic balancers are designed for balancing the vibrations coming from the vehicle’s crankshaft. When the harmonic balancer becomes faulty, you might start feeling some strong vibrations coming from the vehicle’s engine compartment.

2. There Is a Noticeable Wobble in the Harmonic Balancer

Sometimes, the rubber insulators in the harmonic balancer begin to degrade, causing the Harmonic balancer to separate. This can cause noticeable wobbling when running the engine.

3. Unusual Noises

When an engine is running too fast, a faulty Harmonic balancer can cause a knocking, rattling, or squeaking sound that can be misinterpreted as an engine problem.

If the Harmonic balancer fails, the drive belt tensioner may begin moving abnormally. This can cause clicking or squealing noises when the car engine is running.

4. An Illuminated Check Engine Light

Crankshaft position and speed are determined by the crankshaft location (CKP) sensor signal, which is received by the primary computer in your vehicle, also called the powertrain control module (PCM).

The CKP sensor can recognize when it’s coming in contact with a toothed or notched wheel, usually found on the crankshaft and harmonic balancer, when the harmonic balancer isn’t there, though, the CKP sensor signals to the powertrain control module (PCM) that something is off and activates a check engine light.

5. Visible Wear and Damage

Another symptom of a bad harmonic balancer is Visible Wear and Damage. You might notice that the harmonic balancer has become worn out or damaged if you inspect it.

The rubber insulator might be worn out, which could cause the hub and outer part of the harmonic balancer to separate from each other.

Also Read: 700R4 Transmission – Everything You Need To Know

How To Identify A Failing Harmonic Balancer

There are three parts to the harmonic balancer. The inner portion is encased in steel, and it has a hub that bolts with three screws to the crankshaft.

Three 3/8-inch threaded holes on the perpendicular outer edge of the component allow anyone who is interested in removing it from the crankshaft to do so.

There is a rubber insulator separating the 3rd piece of the engine hub. The fan belt wraps itself around the outer rings. The harmonic balancer keeps the crankshaft, pistons, and rods from making a vibration.

Here are some steps you can follow to determine whether or not your harmonic balance is functioning properly.

Step 1

You should examine the harmonic balancer while your engine is running. If you shine a flashlight on it, you can see if it moves smoothly. There is a very good chance that you have a bad harmonic balancer if it is wobbling. Shut down the ignition.

Step 2

Check and see if the fan belt is loose. Grab on the outer part of the harmonic balancer (the one that spins), then begin moving the ring in and out; if it moves, it means the harmonic balancer is faulty, and you need to replace it.

Inspect the rubber ring connecting the outer ring and the inner hub. You should change the harmonic balancer if you notice that the insulator is either cracked, worn out, or missing.

Harmonic Balancer Replacement Cost

A harmonic balancer replacement costs between $100-$550. However, in most cars, the average cost of replacing a harmonic balancer is approximately $200. Harmonic balancer replacement cost can vary depending on a few factors such as the vehicle type, brand, and the type of parts to be used in the replacement.

The cost of replacing a harmonic balancer depends on the type of vehicle and the brand of parts used during the job. The list below estimates the average costs for major brands that charge $100 an hour for labor.

  • Labor hours on a 2009 Toyota 4Runner equipped with a 4.7-liter engine is about 0.9 hours. Getting a replacement part from the factory will cost $261, while a Dayco part should be about $111. To replace the harmonic balancer in general, including the OE parts, it would cost approximately $251, and to use aftermarket parts, would cost about $201.
  • A 2014 Jeep Wrangler equipped with a 3.6-liter engine will take approximately 0.7 hours to replace the harmonic balancer. Using parts by Dayco will cost $46, and a factory replacement part will cost about $84. if you choose to use OE parts, it will cost about $154, and to finish the work using aftermarket parts, will cost approximately $116.
  • Labor time on a 2000 Ford Expedition with a 5.4-liter engine is roughly about 1.4 hours. ATP parts cost $45, while factory replacement parts cost $313. The use of OE parts will cost about $453, and to finish the work using aftermarket parts, would cost $185.
  • A 2004 Volkswagen Jetta equipped with a 2.0-liter engine needs about an hour of work to replace the harmonic balancer, which would cost $49 using aftermarket parts and $277 using factory replacement parts. You’d save some money by using aftermarket replacement parts for the job at $149 total instead of using factory replacement parts that cost about $377.

How To Replace A Harmonic Balancer

With the appropriate tools and knowing the right procedure, most DIYers can easily and quickly change a harmonic balancer. Replacement of a harmonic balancer requires three steps; many DIYers often face difficulties when attempting to remove the central crankshaft bolt. While others may experience difficulty getting the crankshaft pulley bolt back into place, both of these issues have simple solutions once you know what to do.

You need to have an appropriate size socket and an electric or battery-powered impact wrench. You can still get this work done without using the impact wrench, but it would be extremely difficult to complete the task.

The engine will rotate when you press down on the large break bar. Worse, a timing belt can be incorrectly fitted to an engine, causing it to turn backward, produce slack, or skip a tooth.

You can also complete this task by using an ANTI-crankshaft rotating tool. If a one-piece tool comes with the balancer, it simply screws into already installed bolt holes in the harmonic balancer. Typical harmonic balancers include a big offset socket that fits inside a hex slot.

The third option is to use a strap wrench to connect the harmonic balancer’s pulley section.

Follow the steps below to replace a balancer;

  1. To remove the harmonic balancer, disconnect the crankshaft center bolt.
  2. The crankshaft should be removed using the right harmonic balancer Puller. You should not attempt to use a jawed puller unless your harmonic balancer has threaded and factory-drilled holes. A puller like this will only remove the rubber isolation ring’s outer pulley rings. You need to use the right tool.
  3. Change the harmonic balancer unit Toss with a new one that meets the specifications.

NOTE: The old harmonic balancer can be reused once a new oil seal is fitted to the crankshaft. Be sure to inspect the harmonic balancer for any wear. If you notice any kind of wear, you have two choices: change the harmonic balancer or install a harmonic balancer repair sleeve.

Here is a video that shows you the harmonic balancer replacement process

How To Install A Harmonic Balancer Sleeve

You can buy a harmonic balancer sleeve repair kit and also get a new crankshaft oil seal from just about any local auto parts store. Inside the repair kit, you will find all you need to replace a harmonic balancer sleeve, like adhesive, a tool, and a repair sleeve.

  1. You should clean the shaft and wear grooves with a brake cleaner.
  2. Put adhesive on the shaft.
  3. You will need to drive the repair sleeve onto your shaft using the installation tool.
  4. Install a new crankshaft oil seal.
  5. Rub a small quantity of engine oil to the outside of the repair sleeve and then seal it.
  6. The harmonic balancer should be installed again, and the crankshaft bolt torqued following the correct specifications.

Also Read: Ignition Coil Pack – Everything You Need to Know

Frequently Asked Questions About Harmonic Balancer

What is a harmonic balancer?

The harmonic balancer is an accessory drive component at the front of an engine that connects to the crankshaft. The harmonic balancer’s purpose is to reduce engine vibration and pulley for drive belts in some cases.

What happens if a harmonic balancer is damaged?

The engine may shake excessively if the harmonic balancer fails or becomes too old. This shaking can be dangerous for the engine at high speeds and will make it more noticeable.

What are the warning signs of a bad harmonic balancer?

A bad harmonic balancer has the following signs:
1. Engine Vibrations.
2. Notable Harmonic Balancer Wobble.
3. Unusual Noises.
4. Illuminated Check Engine Light
5. Visible Wear and Damage

Can you drive with a bad harmonic balancer?

It is not advisable to drive with a bad harmonic balancer. The main bearings will be worn by the bouncing crankshaft. It can also cause damage to drive belts, and even lead to serious car damage.

What is the cause of a harmonic balancer going bad?

The crankshaft harmonic balancer may become damaged over time from prolonged exposure to chemicals, elements, or old age. The crankshaft can develop cracks, which could lead to its eventual failure.

What is the cost of repairing a harmonic balancer?

A harmonic balancer replacement can run around $200 for most vehicles. The type of vehicle, brand, and type of parts used will all affect the cost of replacing the harmonic balancer.

How often should harmonic balancer be replaced?

On Some engines, a harmonic balancer can last throughout the engine life. However, on some engines, the balancer may only last for 50,000 miles or even less than 10 years.

How can you test a harmonic balancer?

Check the harmonic balancer while your engine is running. To check if the harmonic balancer rotates while in motion, use a flashlight to shine it on it. If the harmonic balancer wobbles, it is probably bad. Turn off the ignition.

Scott Greene is a seasoned automotive technician for over 5 years and has been deep into advanced automotive diagnostics for a couple of years. He Loves writing about Automotive Diagnostics and Repair, Trouble codes, Buyer guides for various car parts and accessories, and lots more. 

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