Smoking deal.
Take some time to go through it and check the bearings for grease and things like that. Older bikes are often in a state of neglect.
Especcialy check the bottom bracket. My used bike started to get a click about a month into having it. Some water got down into the frame at some point before I even bought it. The BB was sealed unit so I manage to force some grease in it and it freed up and is smooth now. It was also loose in the frame (and probably the click was not being tight in the frame). Had I not taken the time to pull it down I would have eventually damaged the threads in the frame.
All the bearings in the bike were pretty dried out. Odd since the guy who I bought it from son worked at a bike shop and supposedly it had been recently tuned up. Smooth as glass now after taking a afternoon to go through everything.
Bikes sould be nearly silent. Chain noise is all you should hear. I hear more noise from the tires when my bike is "right". When the bike starts talking to you they need attention.