It started as a chirping sound, and about two weeks later the balancer separated. I was lucky that it didn't completely come apart and that I was close to home.

Thank God the balancer came apart in a drive thru. If on the road could of been a massive problem. No power steering, metal pulley going thru radiator etc. Especially because my wife was driving to work. Never have heard of this happening in any other car. Did internet search and this is pretty common in the Mustang 4.0 liter. Can't believe no recall.

Started out hearing a faint noise... like a chirping noise... which lead to a loud squealing/chirping all the time. After arguing that something was wrong with the car... found out it was the harmonic balancer... it had all the rubber completely spun out. Recommend checking that if you ever have issues... and buy a new one from Ford... as the after market ones are a piece of sh*t and you will be stuck with buying an OEM part anyway... once your after market one fails you too!