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Harmonic Balancer Repair Sleeve

Make it a point to check the balancer for wear.

Though the timing cover crankshaft (front) seal is much easier to replace than the rear main seal, it can offer its own set of challenges. In many applications, getting to the seal is burdensome, and more times than not, you end up removing the timing cover. At that time, it is a good idea to carry the task one step further and replace the timing chain set since you are already into the front of the motor. Logic tells me that if the seal is worn, then so is the timing chain.

An all-too-common mistake when changing a front timing cover seal is not inspecting the hub of the harmonic balancer for wear. It may be hard to believe, but the seal can actually cut a small groove into the hub of the balancer. When this happens and the new seal is installed, the lip does not make sufficient contact and the job is for naught – the new seal leaks as badly as the old one. It is not due to the seal being faulty. Instead, the groove allows for oil to migrate out. The good news is, the harmonic balancer can easily be repaired with a kit that usually retails for under $10. 

never pry the damper off

The first step is to remove the harmonic damper with the proper tool, known as a puller. This tool works like most pullers attaching to the harmonic balancer with bolts. During operation, the puller employs a jackscrew complete with a protection plate that pushes the balancer off. You never want to pry a harmonic balancer off the crankshaft. Many engines built over the last 20 years do not use a keyway in the balancer and crankshaft snout. This design is just an interference fit, and its use is based on the accessory load that is run from the crankshaft pulley.

To bring closure to this step, when reinstalling the harmonic balancer, an installation tool is required. Never pound the balancer on the crankshaft snout with a hammer or even a dead blow hammer. You will most likely damage the balancer and injure the crankshaft by ramming it against its end. 

When the balancer is removed, inspect it before deciding to install a repair sleeve. If the design allows, inspect the condition of the rubber dampening ring to see if the material is still soft and spring-like. You can use the end of a screwdriver for this, but be gentle; you don’t want to puncture the ring. At this time, check to see if there are no cracks in the harmonic absorbing material and that there are no pieces missing. If it does not pass muster, save the $10 for the sleeve and put it toward a new balancer. 

In most, if not all applications, the sleeve employs an interference fit to the hub of around 0.002 inch. As such, it will need to be pressed on. Since the sleeve goes around the outer diameter of the hub, there is no issue with the keyway to the snout.

install with lubrication

With the timing cover still off, trial-fit the balancer with the sleeve installed through the new seal. Before doing this, though, lubricate the lip seal and the hub of the balancer with engine oil or engine assembly lube if you have it. I like assembly lube since it’s thicker and will stay in place better than oil. You do not want to trial-fit or perform the final assembly with a dry seal and hub.

Most better auto parts stores will carry a balancer hub repair kit. Have the store look up the part number by the engine application. If you need to sleeve a nonautomotive engine, measure the hub diameter and length with a caliper and then go to the auto parts store.

If you have a willing sales rep, that person will pull out a couple of different parts numbers and you can then match to the dimensions you need. This works great on older engines and ensures you a leak-free timing cover seal repair job!

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