The reason it doesn't make noise is that the bearing only keeps the crank from moving back and forth. It doesn't loosen up going around causing excess clearance that causes noise. Does that make sense? I have worked on 3 or 4 that did the same thing that never made a sound and the only way anybody knew there was a problem was the MASSIVE oil leak when the seal pushed out.
Don't be so quick to bad mouth the repair shop. It's not a common problem and unless you know Chrysler and know that that is what causes the crank seal to leak then it's not something you look for. This is why I say ALWAYS take your vehicle to a dealership for repairs. A decent dealership would have seen the problem and told you. Yes you may pay a little more for repairs, but you get an OEM trained mechanic that knows your engine inside and out. That goes for any make of vehicle.
Chef, your harmonic balancer came apart which is what caused your problem. The balancer and pulley are seperated by a layer of rubber. If that comes unbonded then you get that problem. It's a very rare problem. I have worked on cars for 8-9 years and have only seen that happen maybe 2 or 3 times and I don't remember ever seeing it happen on a PT motor.
As far as the tensioner going bad... I have seen that happen after repairs. What happens is that the tensioner works in a very small range. You move it out of that range when you replace the belt. You have to release the tension. When it goes back together sometimes the spring can break or the tensioner can sieze. I don't know if you have ever seen a serpentine belt running, especially when the A/C runs. The tensioner will move quite a bit. The 3.7 v6 in the Jeep Liberty is VERY bad about that.
