How to change a harmonic balancer
Tom Vondrasek | 25th Feb 2024 | 5 minutes to read
Removing a harmonic balancer from an engine is a labour-intensive job. Because the balancer runs off the crankshaft it drives a belt (or belts) which run things like water pumps, alternators, air conditioners, and power steering systems. It is buried at the bottom of the engine and getting to it to be able to remove it is most of the battle.
Once you have done this, the next issue you face is undoing the bolt holding it onto the crankshaft. Then you then need a puller to remove the balancer. The balancer is a tight fit on the crankshaft’s snout and has a keyway to stop them slipping on the crank. It is always a good idea to change the oil seal as well when replacing the balancer.
Note: this is a generic guide, and you may find your vehicle requires something that is not covered in this article. Likewise, there may be parts of it you don’t need to do.
See the general steps for changing a harmonic balancer below:
Tools & Materials
- New balancer and balancer oil seal
- Sockets & spanners
- Screwdriver set
- Torque wrench
- Balancer puller
Notes About the Tools
As each engine is different it pays to do some research on your vehicle to see what you need to do to remove the balancer. It is not something that is covered in the owner’s manual. A workshop manual will cover it.
Be aware that Balancer pullers are available as a generic kit that will do a range of balancers. Always check that the kit has what you need to do your balancer before purchasing. Oil seal remover.
Removing the Harmonic balancer
Prior to initiating the removal process, park the vehicle on a level surface, turn off the engine, and allow it to cool down. Disconnect the negative terminal of the battery to prevent any inadvertent start-ups or electrical hazards while working on the engine.
Locate the harmonic balancer at the front of the engine, typically positioned on the crankshaft. It is usually secured by a large bolt or several smaller bolts, depending on the vehicle's design. Consult the cars manual or reliable online sources to ascertain what needs to be removed to access it.
Note: If you are removing drive belts it is a good opportunity to check them and any tensioners or pulleys to see if they need replacing.
Soak the Hamonic Balancer
Before proceeding, it is a good idea to soak the harmonic balancer bolt or bolts with a penetrating oil to facilitate easier loosening. This step is particularly crucial if the bolts are rusty or have been in place for many years.
Using the appropriate socket size and breaker bar when undoing the harmonic balancer bolt. Apply a steady and controlled force in an anticlockwise direction to loosen the bolt. This bolt is on very tight so the longer the breaker bar the better.
Note: You will need to stop the engine from rotating as the bolt screws into the front of the crankshaft. The high torque setting required to loosen it will easily turn over the engine. There are a number of ways to stop this including using an old drive belt to hold it and bumping the engine on the starter motor with the breaker bar resting against a solid object.
Using the Harmonic Balancer Puller
Once the fastening bolt is loosened and removed, it is time to employ a harmonic balancer puller. Position the puller onto the balancer, ensuring it aligns correctly and engages securely. The pullers central bolt rests on the end of the crankshaft snout and the puller bracket has bolts that screw into the balancer.
As the central bolt is rotated it forces the pullers bracket away from the crankshaft. As the puller applies force, the harmonic balancer should begin to detach from the crankshaft. Exercise patience as it is not quick and as the balancer pulls away from the crankshaft the force required to turn the central bolt decreases. Periodically check the puller's alignment and ensure it remains secure throughout the process.
Once the harmonic balancer is removed, inspect the crankshaft's end and keyway for any damage or irregularities. Compare the old balancer to the new one to make sure it is the same and you have the correct balancer to install on your engine.
Installing the New Harmonic Balancer
Before installing a new harmonic balancer, change the oil seal. Clean the crankshaft's mating surface to ensure a smooth and secure fit. Remove any debris, oil, or residue that might impede proper installation.
When reinstalling the harmonic balancer, align it correctly with the crankshaft ensuring the keyway lines up with the gap in the balancer. You can use the central bolt you removed to gently push the new balancer onto the crankshaft’s snout. Use a torque wrench to fasten the balancer bolt to the manufacturer-specified torque setting. Stick to these specifications to prevent over or under tightening.
Note: To torque the bolt correctly you will need to stop the engine from rotating. Like the removal process there are a number of ways to do this.
Reverse the removal process of all belts and accessories you removed to get to the harmonic balancer. Replace any worn out parts along the way.
Check the Alignment of the Harmonic Balancer
Lastly, reconnect the negative terminal of the battery that was disconnected earlier. Start the engine and allow it to run for a few minutes, monitoring the harmonic balancer's operation to ensure proper alignment and functionality.
In summary, replacing a harmonic balancer on an engine requires doing your homework on the type of engine you have, and the process required to remove and install the new one. By following these outlined steps, supported by reliable sources and practical knowledge, you can effectively carry out this task.
You may need to buy a puller, which if you work on cars is not a bad investment. It is a major job given a lot of the items you need to remove and sets you up for being able to change a timing belt, so don’t go into it lightly.
