The harmonic balancer is bolted to the front of the engine’s crankshaft. It has two primary parts; the first is a heavy machined inner cast piece, and the second is an outer cast piece that drives the serpentine belt. These are joined together with a thick rubber ring.
Replacement is fairly simple given the proper tools, though access isn’t always easy. The serpentine belt needs to be removed first, and then the centre bolt that holds the balancer in place. Some harmonic balancers can be simply removed at that point, but many require a specific puller to remove.
Cost of Harmonic Balancer Replacement
On average, for most vehicles, it can cost about £170 to replace a harmonic balancer.
The cost of replacing the harmonic balancer varies mainly due to the type and model of the vehicle and the type and brand of parts used. To illustrate, below are some specific estimated costs for some common vehicles using a labour rate of £70 to £100 per hour:
- For a 2009 Toyota 4Runner with a 4.7-liter engine, the estimated labour time is around 0.9 of an hour. A factory replacement part costs around £230 and a non-OEM part costs about £90. The total cost of the harmonic balancer replacement would be around £290 using OE parts and about £153 using aftermarket parts.
- For a 2014 Jeep Wrangler with a 3.6-liter engine, the estimated labour time is around 0.7 of an hour. A factory replacement part costs about £70 and a non-factory part costs about £38. The total cost to complete the job would be around £120 using OE parts and about £85 using aftermarket parts.
- For a 2000 Ford Expedition with a 5.4-liter engine, the estimated labour time is around 1.4 hours. A factory replacement part costs about £265 and an aftermarket part costs about £38. The total cost to complete the job would be around £365 using OE parts and about £135 using aftermarket parts.
- For a 2004 Volkswagen Jetta with a 2.0-liter engine, the estimated labour time is around 1 hour. A factory replacement part costs about £235 and a non-original part costs about £40. The total cost to complete the job would be around £305 using factory parts and about £110 using aftermarket parts.
What Does Harmonic Balancer Do?
The main role of the harmonic balancer is to absorb and dampen the crankshaft vibrations. All the various periodic forces of piston movement and cylinder firing can resonate along the length of the crankshaft. This can result in amplified harmonic vibrations at different engine RPMs and loads; the harmonic balancer absorbs and minimises these.
The second role of the harmonic balancer is to transfer the engine’s rotating force to the drive belt in order to run the engine accessories. The outer casting that drives the belt is connected to the inner casting that is driven by the crank by a rubber dampening ring.
The main way that a harmonic balancer fails is when the rubber ring deteriorates or separates, allowing the two cast parts to partially or fully detach from each other. That can reduce the dampening effect and cause problems with the belt alignment.
Other Related Parts That Might Be Recommended
Probably the most common additional service recommendation would be to replace the front crank seal, which seals against oil leaks where the crankshaft projects through the timing cover. If there are any signs that the crank seal may be leaking, the time to replace it would be when the harmonic balancer is already removed. The additional labour is usually just a couple of tenths of an hour, and the part cost is relatively small.
PRO TIP – Even if there aren’t any signs of front crank seal issues, it’s still a reasonable thing to replace while it is accessible as a matter of preventative maintenance.
On the other hand, the harmonic balancer has a machined surface that the front crank seal bears against. When the front crank seal itself is being replaced for an oil leak, the harmonic balancer should be inspected and replaced if necessary. Sometimes the seal can wear a groove in the balancer’s sealing surface if it’s run in less than ideal conditions or in a gritty environment, and any imperfection there can prevent effective sealing and cause a leak.
Another part that might be recommended for replacement is the serpentine belt. If a harmonic balancer was replaced for a belt alignment problem, that may have damaged the belt.
PRO TIP – If the belt isn’t damaged but there is any other reason to replace the belt while it is off, or if it may be due for age or mileage, it is most economical to do when it is already off and no additional labour charge would be necessary.
One other symptom sometimes is that if the harmonic belt tensioner’s rubber ring begins to fail, that can cause the main belt drive to run in a less than perfect circle, which would cause the belt tensioner to constantly work to adjust the belt circuit run. This constant work can lead to a failure of the belt tensioner pivot point.
Sometimes, a failed belt tensioner can be caused by a harmonic balancer issue. It is worth taking a look at the condition of the belt tensioner when a harmonic balancer needs to be replaced.
Usually, there would be belt noise on starting the engine. Other things cause that more commonly, but that’s one symptom where the harmonic balancer should be checked.
Possibly, but the risk is that it could throw the serpentine belt off, which usually drives the water pump and power steering pump. In which case it would be difficult to drive and the engine would overheat fairly soon after.
On most engines, it takes a little over an hour.