Harmonic Balancer

What is a harmonic balancer and where is it located?

While the harmonic balancer may sound like it should be some sort of quest item in a video game or fantasy novel, it is actually an important part of your engine’s functioning. It can be found at the front of the engine connected to the end of the crankshaft. It helps to dampen the vibrations of the crankshaft, and for this reason it is sometimes called a crankshaft damper (or dampener) or a torsional damper (or dampener). In addition to these, you may also hear a few other names used when referring to a harmonic balancer, including:

• Harmonic damper 
• Crank pulley damper
• Vibration damper

The crankshaft converts the up and down motion of the engine pistons into rotational motion needed to move the vehicle. As the pistons act on the crankshaft, it is subject to certain vibrations. At high revolutions per minute these vibrations could be damaging to the crankshaft if not dampened. 

That’s where the harmonic balancer comes in. It is connected to the crankshaft and absorbs some of the torsional vibrations. To accomplish this, it consists of three parts: a hub that connects it to the crankshaft, a rubber disc that can flex and bend by small increments to absorb the vibrations, and a metal ring on the outside which gives it weight. 

In many vehicles, the harmonic balancer serves double duty, also acting as the crank shaft pulley, which drives the serpentine belt to run the water pump, alternator, and other engine accessories. For this purpose, the outside of the ring will have timing marks and pulley grooves.

How do I know if my harmonic balancer needs to be replaced?

Since the harmonic balancer’s job is to dampen vibrations, any engine vibration is a sign that the harmonic balancer may be worn or damaged. You may find that the engine vibrates at particular RPM levels. This is because, at certain frequencies, the crankshaft may vibrate at a harmonic resonance, causing a particularly strong vibration. Think of those old films of bridges shaking and falling apart in a strong wind. That’s what could happen to your crankshaft without your harmonic balancer. 

The ability of the harmonic balancer to dampen torsional vibrations can be compromised by damage or wear to the rubber ring. Heat generated by the engine and from the forces experienced by the harmonic balancer can wear down the rubber over time. The rubber can also be degraded by oil leaking from the engine. If the rubber wears down it may separate from the outer metal ring, making the harmonic balancer less effective. Separation of the outer ring may cause a knocking noise. If the outer ring separates completely from the rubber and comes off, it could damage nearby engine parts. 

A failing harmonic balancer, in its capacity as the crankshaft pulley, may also cause the serpentine belt to slip. This can result in poor acceleration, engine misfiring or problems with systems like the air conditioning, alternator or water pump. If this is occurring, you may find that the pulley’s timing marks are off or that the belt is damaged. 

An ineffective harmonic balancer can lead to damage to the crankshaft which will cause more serious problems and result in expensive major repairs. If there is something wrong with your harmonic balancer, you ought to fix it before it causes further problems. 

Can I replace a harmonic balancer myself?

Replacing the harmonic balancer will require effort, patience, and a variety of tools as well as a specialty tool called a harmonic balancer puller. The engine compartment layout varies from one vehicle to another, so accessing the harmonic balancer will be different on different models. In some cases, it will require you to remove other engine parts. It is important to be careful with the harmonic balancer as you are installing it, because if it suffers any damage during installation, its balance may be thrown off and you’ll be just as bad off as you were before. A harmonic balancer puller helps you to remove the harmonic balancer without damaging the engine, avoiding these sorts of problems. 

The repair may involve the removal of systems like the air intake, radiator, and serpentine belt to access the harmonic balancer. To remove the balancer you will need a tool called a harmonic balancer puller and a method to keep the crankshaft in place, such as making a holding tool with a plank of wood. Keep the crank shaft in place and loosen the balancer bolt. Then mount the puller with two or three bolts to the balancer, and tighten the puller. This should loosen the harmonic balancer pulley and then pull it free. 

To reinstall, line up the balancer and tap it into place. Then tighten the harmonic balancer bolt into place. Keep the crankshaft in place, and tighten the bolt to the pulley. There are many ways to install the bolt, like using a special tool or building your own holding tool and it is best to stick with a method good for your engine. Then torque the harmonic balancer bolt to the vehicle's torque specification. Then reinstall the serpentine belt and any other parts removed like the air intake and engine cover.