I need someone's help locating a sound I am hearing coming from what sounds like the front of the engine. I just bought a 99 Trans Am with 118k miles. When the engine is running there is a sound that sounds like something is rubbing. Its like a plastic on metal sound. It almost sounds like rocks. It hard to explain. You can hear it over the exhaust. The engine runs strong so I don't think it is anything internal but I could be wrong. I tried to search but I'm not sure how to search for this sounds. Any ideas?

 

Look at the AC compressor. Does the compressor pully have rust on it? If so I had the same problem (I think). I only figured it out after weeks of not using the AC in the summer. The sound seemed to go away. Then when the girl rides with me she wants a cool car so the AC comes on. After I turn it off I get a whining/grinding noise while the car still runs. What I did was spray some honda oring safe chain lube right on the pully while the ac is on. Turned off the AC and the sound was almost gone. Replace the belt if you do that. Didn't think about it until after, but I needed a new one anyway. I don't have AC now, but that was my problem.

 

You Tube LS1 rubbing sound and have a listen, Thats how I found out about my spun rod bearing.

 

Thanks for the help guys. It turns out it was the water pump. I replaced it Sunday and it sounds great now.