i've heard that harmonic balancer wear out in 10-15 years and i wanted to know how to tell if its worn out?
Funny thing you mention this, I have a jeep cherokee and was leaving work when I heard this aweful noise and lost all my guages. I immediately pulled off the road, popped the hood, and there was no serpentine belt to be found. Upon further inspection and scratching of the head I noticed the crank pulley was GONE!. The lower pully is made onto the balancer of most of the newer vehicles (unlike my mav). So I had to install a new balancer and belt. funny thing is, My sister called and said her olds was making a funny noise so I looked at it and her balancer was bad too. but the weirdest thing was that on the way to get her new balancer the bolts broke off of the pulley on the balancer of her truck.... .. I would call this a streak of bad luck. I just bought a "Fluidamper" for the mav and some good stainless bolts. By the way, the "Fluidamper" has no rubber ring to wear out..so to answer the question. YES they can wear out from heat and oil contamination..
The same assembly on my the 4.0 in my wife's cherokee started to come apart also. The outer pulley part slid aft and contacted the front of the engine resulting in NOISE! Sounds like yours slid forward.
Yep it completely dissapeared!! Basically a vibration damper and harmonic balancer are the same,:bananaman just different names..
fluid dampner has fluid in it to counteract the vibrations.....the old style harmonic balancer used the rubber to keep the vibrations quiet.....
Those 4.0s are notorious for that. Alot of times there is damage to the wp or ps pump that could be missed or undetected.