I know this might sound stupid but what actually make an engine run louder when it gets older? For example my car,when it was new, ran so quiet it was hard to tell if it was running or not. But now after 75K it runs louder, like it is easy to tell it is running.It isn't running bad or anything,it runs great. Is it just internal wear of the engine or what? I am not looking for a fix, but just something I have just wondered about. You know what I am saying?

 

what do you hear that sounds louder (exhaust, tapping, etc)?

 

It's not the exhaust, it's just from under the hood.