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Common Harmonic Balancer Failures: Signs And Symptoms!

An often overlooked auto part is the harmonic balancer (also known as a vibration damper or crankshaft damper). Although this component is often forgotten, when it fails it can cause major problems, even serious engine damage. To avoid this, it is good that you know the common failures of a harmonic balancer .

Do you have the feeling that you may have a faulty harmonic balancer? If you experience one or more of the symptoms that we are going to show you in this post, you may be right.

What is and how does a harmonic balancer work?

What is the function of a harmonic balancer? The main purpose of the balancer is to absorb vibrations applied to the engine crankshaft.

In a four-stroke engine, each piston makes four different strokes (intake, compression, power, and exhaust) as the crankshaft rotates. When a piston moves down during the power stroke, it causes the crankshaft to speed up.

At the same time, another piston moves up during the compression stroke, forcing the crankshaft to slow down . As a result, opposing forces are applied to the crankshaft, creating a dangerous resonance phenomenon.

The balancer or harmonic balancer moderates the high-frequency vibrations acting on the crankshaft. A typical balancer has a central hub, an inertia ring, and a rubber insulator (some designs use viscous fluid instead of rubber). The center hub is bolted to the end of the crankshaft. As the crankshaft rotates, the inertia ring and rubber ring absorb part of the resulting vibrations.

Additionally, the harmonic balancer has a pulley (integrated or bolt-on) that connects to the engine drive belt. When the engine is running, the pulley turns the belt, which, in turn, turns the accessories driven by the engine (alternator, air conditioning compressor, etc.).

Common Signs and Failures of a Harmonic Balancer

When this component gets damaged, it can cause a number of problems. Common failures of a bad harmonic balancer include

1- Engine vibrations

The harmonic balancer’s job is to dampen vibrations applied to the crankshaft . As a result, when the balancer fails, you may feel significant vibration from the engine bay.

2- Notable swing arm of the harmonic balancer

When the rubber insulator starts to deteriorate, the balancer often starts to separate, creating a noticeable wobble when the engine is running.

3- Unusual noises

A faulty balancer can cause a knocking, rattling, or screeching sound that corresponds with engine speed. In some cases, the noise is severe enough to be mistaken for an internal engine problem.

Also, a balancer that is beginning to fail can cause abnormal movement of the drive belt or automatic transmission belt tensioner, resulting in a clicking or screeching noise when the engine is running .

4- Check Engine light illuminated

Often referred to as the powertrain control module (PCM), your car’s main computer relies on a signal from the crankshaft position (CKP) sensor to determine the position and speed of the crankshaft.

The CKP sensor reads a sprocket or notched wheel that is usually located on the crankshaft or harmonic balancer. If the harmonic balancer fails, it can cause the sensor to create an abnormal signal, causing the PCM to turn on the check engine light.

5- Visible wear or damage

If you take a look at the harmonic balancer, you may be able to see some visible wear or damage . For example, the rubber insulator may have deteriorated, resulting in a gap between the hub and the outside of the balancer. This is considered one of the common harmonic balancer failures that even a novice mechanic can notice.

What happens when a harmonic balancer fails?

Although the harmonic balancer may seem quite simple, if it fails it can cause major problems. If the balancer does not damp unwanted vibrations from the crankshaft, it can cause engine failure, such as worn connecting rod bearings and broken crankshaft.

A faulty balancer can also damage the belt and engine-driven accessories. It is also possible for the balancer to come off, causing the destruction of various engine components.

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