I discovered a failed harmonic balancer on a friend's '96 Mustang 3.8 V6 auto (no performance mods; bone stock) that seems to be pretty unusual.
Take a look at the pictures here:
http://community.webshots.com/album/552022226RktMDS
Yes, the balancer is broken into two pieces. And look at that keyway: It's more than *twice* as wide as it should be.
I suspect that the balancer cracked some time ago - but was held in place by the crankshaft bolt. As long as everything stayed in place, it still worked OK. But the vibration started abrading the keyway and causing movement along the crack line. The '96 gets its ignition timing from the crank sensor and the star gear on the balancer, so timing quick got out of whack.
Questions:
- Any idea what really caused a failure like this? Has anyone seen a similar failure?
- I plan to simply replace the balancer, put it all back together and hope for the best. Are there issues I should be aware of, or other problems I may have missed?
Thanks for any insights.
(Apology to admin/moderator: I also posted this is the "Problem Diagnosis" forum - before realizing how little traffic it gets)