I have a 99 ek with a b16. if i hold the rpm's at 1200 a weird rubbing or grinding noise comes from the pulley timing belt area. but goes away any other rpm. I Know its not a rod bearing its too loud and know what those sound like. I'm just stumped. any ideas anyone?

thanks

 

sounds like something is just vibrating, ever had somthing laying in your trunk and heard it vibrate at a certain rpm and no other?