Ok so I have had my Sonata for 4 years and its been great up until 2 months ago. I heard this god awful noise when I cranked it up and took it into my local mechanic to be checked. He said it was the Harmonic Balancer and was able to get me a dorman brand one from Carquest for $115.00. It was replaced and all was well for 6 weeks and then I heard the noise again, went in and he said it had separated so it had to be replaced again. All was good for 13 days and AGAIN it fell apart on me this time in the middle of the highway (very scary). Took 8 days to get another one in, had to pay $300.00 to rent a car and was just totally OVER this situation. ONE day later after getting the car back I cranked it up and it started making the noise again ONE DAY and all I had done was drive it from the shop to my house which is maybe 8 miles at the most. I lost it at this point and went straight to my mechanic. He took it off (again it was separated) and I told him this time I wanted a refund on it and took my butt up to the Hyundai dealer for the part, I had to pay $180.00 but I figured maybe this would work. The service manager at Hyundai told me the my crank might be walking or wobbling and if that was the case the car isnt worth saving. He said to have my mechanic check the motor and other pulleys and all of them are fine, the motor runs great and so they put the Hyundai harmonic balancer on and I am praying this time it lasts. I was wondering if anyone else has had this much trouble with after market parts like dorman and other opinions on this happening to me. There are 94,000 miles on my car.