i have a 1990 1.6L miata...whenever i am idling, there is a slight hum from under the hood....the hum will continue until i give the care a little gas, maybe 1300 rpms....as soon as i realese the clutch and the car goes back to idle rpms, the humming noise comes right back....this has no effect on the way the car runs, it is just very annoying....i have even tried to open the hood and give it throttle, the hum stops but i cannot pin-point an exact location of it....

please help!!!!!!

 

imchilean,
You need a way to localise all the sounds coming from the engine at idle. The best way is with an automotive stethescope, it will have a contact rod and moving it to differrent locations in the engine room while you listen, can track down noises. I've also had good results using a long screwdriver with the handle against my ear and the other end against suspected noisy spots. One last method involves using a 3 or 4 foot long piece of garden hose with one end to the ear. with the last method, you don't have to actualy touch suspected offenders, just get near them. Hope this helps.