Q: Had harmonic balancer replaced twice in 3 months, one week after fixing it the 2nd time the engine threw a rod

The only way to determine what is broken, and who is potentially responsible or at fault, is to physically examine the engine. Speculation in the absence of a physical, on site examination is not going to help you. If you are asking generally, "can a mechanic cause damage to my car?" of course the answer is emphatically yes and that is why you should be exceptionally careful in who you deal with and ALWAYS ask tons of questions in order to gauge "who" you are dealing with. An easy decision rule, covering ALL aspects of life, is don’t deal with anybody who doesn’t love to answer YOUR questions, in this case about your car, that you spent your hard earned money on.

With regard to the harmonic balancer, when the FIRST replacement was performed, that should have concluded it. That is, the first repair should have been lasting. As far as why the first repair failed, again hard to say without what we call a forensic exam, but a possibility is the pulley bolt may have been either under tightened or over tightened. Either mistake can cause the balancer to come off. If there is internal engine damage, the engine can be repaired or replaced. Either is no big deal and if you desire to consider your options, and costs, please simply contact YourMechanic and a certified mechanic will be dispatched to diagnose what you have and set out for you repair strategies. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.