6.9 / 7.3 IDI Harmonic Balancer (Vibration Damper) Replacement Process

The harmonic balancer, also known as the “vibration damper,” sits on the front end of the crankshaft.  It is press fitted on the shaft with a small steel woodruff key to orient the direction.  If a person needs to service the crankshaft, remove the front engine plate, replace the front main seal, or do other internal repairs on their IDI engine, the harmonic balancer may need to be removed.  Also, if the harmonic balance has damage, it may affect engine timing and may need replacement.  This procedure will require special tools that can usually be rented for free at any auto parts store.   The following article entails my process for removing the balancer.

There are several components fastened to the front of the harmonic balancer that need to be removed.  Using the diagram above, here are the names:

  1. Generator Drive Pulley (for the v-belt version, not for serpentine belts)
  2. Hex Head Bolt (15/16″)
  3. Crankshaft Washer
  4. Vibration Damper (Harmonic Balancer)
  5. Crankshaft Pulley (for the v-belt version, not for serpentine belts)

The front pulley assembly has four retaining bolts and a retaining disc (not photographed).  I needed to remove these four bolts (that reach down through the harmonic balancer) before I could extract the balancer from the crankshaft drive.  NOTE: the center crankshaft bolt (15/16″) does not need to be removed to get the pulley off.

Sometimes the bolts are rusted on or torqued on so tight that trying to undo them will turn the engine cycle.  Since I had the engine on the stand, I just jammed a 3/8″ drive extension in the flywheel/flexplate to stop the spin.  If the engine was in the vehicle, a couple v-belts looped around the pulley held by a friend should be enough to keep the engine from cycling.

Once the pulley was removed, the rubber layer showed obvious wear and tear.  This balancer will need to be replaced or have the sleeve repaired.

Before the Harmonic Balancer Puller can be used, the main crankshaft bolt must be removed.  Again, if turning the bolt turns the engine, use one of the aforementioned methods to constrict the rotation.

I removed the bolt and crankshaft washer.  On the left side of the cavity, you can see the slot for the woodruff pin.  I sprayed in some penetrating oil in the hopes that maybe the puller may have an easier time to extract the balancer from the surface of the crankshaft.

The next process required a special tool, a harmonic balancer puller.  It is basically a set of high-strength bolts, a compression cap, and puller flange.  The largest bolt threads into the center threads of the puller flange.  Then the kit should have some bolts that screw into two opposing balancer threads.

The compression cap should be inserted on the end of the big bolt; it distributes the compression load on the crankshaft equally so it doesn’t damage the shaft.  Also, it is imperative that the tool be liberally greased on the main bolt threads and compression cap, so that they can spin without binding.  In the image below, you can see the reddish-purple grease coating my puller threads and inside the compression cap.

The tool is pretty simple.  I threaded on the secondary bolts as far as they can go.  If I didn’t get enough threads, it might strip the threads out when I pull it out.  Also, the secondary bolts need to be exactly the same length so that the puller is parallel to the face of the harmonic balancer.  Using a socket wrench, turn the larger bolt and compression nut until it situates in the center of the crankshaft hole.  Then using the socket wrench, continue to turn the center shaft until it starts pulling the balancer off the shaft.

Eventually it will start sliding off the crankshaft.


Before I put my harmonic balancer back on, using a white-out pen, I drew a line in the timing groove.  Why paint the line white?  Once the engine is reassembled and started, you have to time the engine.  A bright white line shows up really well with a timing gun strobe light.  I’ve found that the metal-tipped white-out pens are the best, because they fit perfectly in the balancer groove.  It allows the paint to coat the bottom of the groove.  If you use a standard white-out pen (without a metal tip) or a white-out brush, it will likely not make a clean line like the metal ones do.

Photos of how I installed the balancer will follow.  Using a Grade 8 long bolt with a nut and large washer, I screwed the bolt into the crankshaft drive, then pushed the balancer on with the washer.

When reinstalling, I had to make sure the new harmonic balancer did not conflict with the timing flange on the front engine plate.  There should be a small gap, and at the moment, I can’t find the spec in the manual.  I’ll update that once I find the photos.

No warranty. You are responsible for your vehicle. For novelty use only. Not responsible for anything or anyone. Not responsible for damage to your vehicle, you, or anyone or anything.

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