A bad harmonic balancer can cause a knocking noise. The harmonic balancer doesn't actually produce the noise, but it can cause the noise in the engine.
Hard to say. However, if the "rubber gasket" you're talking about is the center bushing on your harmonic balancer, that could throw your Harmonic balancer out of balance. This could easily make it shake to beat the band which in turn could be the knocking noise you're hearing. I suggest you get it looked at immediatly. If that is what happened, your engine won't survive long.
I would contact the local parts store and replace the harmonic balancer if you think it is bad. a bad balancer can cause failure in the crankshaft bearings because of the shake.
Most common cause is a bad water pump, or harmonic balancer. Other possible causes are bad motor, bad supercharger, cracked flyweel, or in rare instances a bad torque converter.
== == I do believe if you hear a knocking noise that your crank shaft could be failing. Which means you will need a new engine. Have it checked out. Replace the harmonic balancer they will make a bad knocking noise. When you start it and the oil light goes out and it knocks, this is what is wrong with it.
Bad bearing or rod
harmonic balance maybe bad
the cause of this is probably a bad u joint
did you disassemble the engine to determine the rod condition? some harmonic balancers will make a knocking sound when they go bad
You have one or more tires out of balance.
If you meant harmonic balancer keeps going bad you probably have a bent pulley.
A bad rod bearing