Timing Chain

[very tired]

What are the SIGNS of a bad timing chain? Noises, etc. What is the expected lifeOf the chain? I have no idea how old mine is. I have my lst MB and trying to figure out a noise. The car has 154,000 and immaculate condition with service records. The person I bought it from said the chain had been checked at the last oil chain 1500 miles before I bought it. It is a 1989 300SEL>A noise that happens at times worries me. It sound like a soft grinding noise almost like wind blowing. It stops if I touch the break. I am trying to eliminate something simple before the mechanice. I will be new to the MB mechanic and heard many stories about costly repairs! Don't want to drive on any long road trips until I make sure it is nothing.