i own an 94' acura integra ls auto. recently i noticed when the engine would rev a wierd metallic noise would emit from the car, it's only audible if i have the windows open and theirs a wall or row of cars next to me. the sound that comes out sounds like something hard grazing against a metal fan. it usually only does it when i'm at 4000+ rpms or even low if i have been driving a while. I know its kind of dumb to ask: "my car makes this noise, what's wrong" but i dont know much about cars and hope it's nothing serious. Also, about how much does it cost to take your car in to change the timing belt? thanks.

 

The noise you are hearing is probably a loose "heatshield" on the exhaust system..this is a very common problem.. bang on the exhaust to see if you can duplicate the noise.. see this post.. https://honda-tech.com/zerothread?id=70584

When changing the timing belt is is also recommended to replace the water pump as well, parts and labor usually run around $350.. your mileage(cost ) may vary..