What Is A Harmonic Balancer? How To Fix When It Goes Bad

Numerous car compartments play a role in maintaining engine performance and speed control. Yet, for some reason, harmonic balancers are always forgotten! 

Contrary to popular belief that they only seize a minor part of the vehicle structure, these seemingly small devices are the most decisive factors in the crankshaft’s smooth operation.

Without them, violent vibrations will keep occurring!

So what is a harmonic balancer and its working mechanism? What should we do when it breaks down or malfunctions?

Our article will clarify them all, providing tried-and-true tips that have been proven effective.

What Is A Harmonic Balancer? What Does A Harmonic Balancer Do?

What Is A Harmonic Balancer

What is the harmonic balancer? In the simplest terms, harmonic balancers absorb torsional crank motions to keep them from being transferred to other engine compartments.

Indeed, despite the term “balancer” in its name, a harmonic balancer in a car is not designed to balance anything (surprise!).

Due to its absorbing nature, some experts and seasoned car drivers also refer to it as “dampener” or “crankshaft damper” instead. Without its mechanism, your automobile crankshaft cannot last long.

So how exactly does the torsional vibration occur – and how do these balancers stop them?

When the cylinder fires in the engine, it will move upwards and downwards, producing torque that will get transferred to your crankshaft snout – a device that converts engine powers into rotating movements to turn the car’s wheels.

The forces acting on these crankshafts are tremendous, twisting every time the cylinder operates.

Harmonic vibration in the crankshaft is inevitable and might even worsen at particular frequencies where the shaft resonates.

Here is where your harmonic damper springs into action: its circular device (comprising metal and rubber) is activated at the crankshaft’s front end to absorb every vibrating movement.

The device is often linked tightly to the crankshaft pulley, driving accessories like how a typical air conditioner runs.

Thanks to the rubber within this pulley, crankshaft vibrations are always kept at safe levels. Risks of crankshaft failure are also reduced! 

What Are The Signals of Bad Harmonic Balancers

Now that we have tackled the question, What is harmonic balancer?, another problem arises: how to troubleshoot and recognize symptoms of a failing one?

When crankshaft harmonics fail, varied symptoms will show up. Here are some of the most popular signals/red flags to look out for in those cases: 

Rough Engine Vibrations

As you now know, the primary job of any standard harmonic balancer is to absorb and reduce violent torsion within the crankshaft.

Hence, when the balancers fail to do so, intense vibrations from the internal combustion engines will occur.

Transparent Wobbles in The Harmonic Balancers

Once the rubber isolators start to suffer from wear-down and deterioration, the balancers’ combustion chamber will separate, leading to noticeable wobbles when your gasoline engine components operate.

Strange Noises

Faulty balancers often result in squeaking, rattling, or knocking noises when accelerating.

In worse cases, these humming sounds are so loud that novices even mistake them for issues in the internal engine subsystems.

On another note, failing balancers might also lead to abnormal drive belt movements or stuttering serpentine belt tensioners. Squealing/clicking noises also stem from there during the car’s run.

Blinking Check Engine Lights

The car’s primary computer – often called PCM (Powertrain control modules) depends heavily on CKP (crankshaft position) sensor indicators to evaluate the crankshaft speed and placement.

Specifically, the CKP helps you read notched/toothed wheels usually placed on the vibration damper.

So once the stock dampers break down, CKP sensors will inevitably create abnormal signals, pushing the Check Engine lights to flash intermittently.

Visible Damage and Wear

Look closer at the balancers. Is there visible damage and wear? By illustration, deteriorating rubber insulators can cause separation between the balancer’s outer portion and hubs. Note down all of them!

What Will Happen If You Ignore These Symptoms?

The balancers take charge of absorbing vibrations, meaning even a child can guess what will happen to your car when they fail to do their job.

Aside from annoying crankshaft vibrations, other disastrous issues follow suit, such as basic engine failures, broken crankshafts and belts, defective engine accessories, and worn bearings.

Worse, untreated balancers might even fly apart over time, destroying numerous underhood components. So without any doubt, troubleshooting all the signals we just mentioned is a must.

How to Replace Bad Harmonic Balancers?

How to Replace Bad Harmonic Balancers

Step 1. Jack Your Car

Jack the vehicle high enough for you to access the harmonic balancer (connected to the crankshafts at the motor’s front).

Step 2. Pull Off The Cogged Belts

The next step is to detach every accessory drive belt. You can rotate a spring-loaded, automatic belt tensioner on certain modern-day engines to loosen these belts.

Remember to take pictures of its routings for later reference.

Step 3. Pull Off The Balancer Bolt

Extract the bolts. How to do so? Seize the balancers on the spot with a strap wrench, then use ratchet handles/breaker bars and sockets to loosen the bolts.

These bolts are often tightly installed, so exert as much force as possible!

Step 4. Pull Off The Balancer Unit

Pick a gear puller. Then place the unit hooks in places that can not break easily (ex: pulley section lips).

Some cars incorporate threaded holes within the balancer – which you can use for puller attachment. Tighten the bolt’s center with breaker bars/ratchet handles till the balancers break free.

Step 5. Install Your New Balancer

Align woodruff key slots and the new balancers with woodruff keys. Slide the balancers carefully into the crankshaft.

Step 6. Reinstall The Belts And Start Your Car

Loosen/rotate the belt tensioners to return the belt to its spot. Then remove the jack stand, lower your car, and start it to confirm proper reassembly.


What is a harmonic balancer? Our well-researched article has delved deep into this question, providing all the necessary insight behind its mechanism and functions.

These tips also prove practical when your balancer inevitably breaks down; all potential causes and symptoms have been provided, ensuring you and the auto shop you turn to can give them quick fixes!

Like with any other car part, keeping a consistent maintenance schedule for your car harmonic balancer is a must. Do not forget to check them carefully after every ride, either.

For more questions on harmonic balancer purpose, feel free to contact Bryan’s Garage.

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