Q: Harmonic balancer broke replaced now won't start

There are two main possibilities. Depending on how or why the balancer failed (e.g., did it fail suddenly accompanied by the car engine completely stopping), it is possible the timing belt has slipped or is even broken. It is also possible that a nearby sensor, such as the crankshaft position sensor (CPS), or sensor wiring, was damaged during the failure or was not properly reconnected. Related to this, the CPS in your application might read off of the balancer/pulley assembly. If you don’t have the correct balancer (part number), that could even be an issue because your CPS will not function and the car won’t start or run.

If none of those circumstances exist, the second possible explanation for your no start condition is that it is a coincidence not related to the balancer replacement and this is simply due to an ignition or fuel system problem (or starting system problem if the engine is not even turning over). If you would like an expert to conduct an in-depth diagnosis of this, have a professional technician from YourMechanic inspect the starting issue to have this corrected.