Toyota Repair: 98 toyota Corolla Rattle Noise, toyota corolla, toyota dealership

Question
I recently had the drive belt and tensioner replaced at the toyota dealership. when i got the car back, I noticed a rattle/tapping noise in the engine.  It sounds like the timming chain?  Before repairs where done, there was little to no noise at all.  My question is when replacing the drive belt and tensioner does it effect the timming chain? My corolla has 150,000 Miles and has been very reliable. also what is the estimate cost of replacing a timming chain? and the effects if timming chain was to break. Symtoms if you timming chain needs to be replace.  thanks a million  

Answer
I doubt if the timing chain is the problem, did you take the car back to the dealer and ask them what the noise was and why it is there after they worked on it? Replacing the tensioner and belt has no effect on the timing chain, there is something else, you should take it back and have them recheck their work and come up with an explanation.