The $10 fix: Harmonic balancer repair sleeve.

The $10 fix: Harmonic balancer repair sleeve.

August 24, 2020 0 By Ray Bohacz

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.

Often, you end up removing the timing cover. At that time, it is good to carry the task one step farther and replace the timing chain set since you are already into the front of the motor.

My logic being 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 cut a small groove into the balancer’s hub. 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 severely as the old one. It is not due to the seal being faulty; the groove allows for the oil to migrate out. The good news is the harmonic balancer can easily be repaired with a kit that usually retails for under $10.00. There are some caveats, though.

The first step is to remove the harmonic damper with the proper tool known as a puller. The tool works like most pullers and attaches to the harmonic balancer with bolts. Then, a jackscrew with a protection plate for the crankshaft thread pushes the balancer off. You never want to pry a harmonic balancer off the crankshaft.

Many engines built over the last twenty 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 endplay.

When the balancer is removed from the engine, it is essential to thoroughly inspect it before you decide to install a repair sleeve.

If the design allows, check the rubber dampening ring condition 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 do not want to puncture it. Check to ensure there are no cracks in the harmonic absorbing material and that no pieces are missing. If it does not pass muster, save the ten dollars 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, so it needs to be pressed on. Since the sleeve goes around the O.D. of the hub, there is no issue with the snout’s keyway.

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 either engine oil or engine assembly lube if you have it. I like assembly lube since it is 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. They will look up the part number by the engine application.

If you need to sleeve a non-automotive engine, measure the hub diameter and length with a caliper and go to the auto part store.

If you have a willing, old-school counterman, he will pull out a couple of different parts numbers, and you can then match it up to the dimensions you need. This works great on older agricultural engines and makes sure you have a leak-free timing cover seal repair job.