hi, i've recently purchased 2004 4cyl. Tiburon for very good price. but the problem is .. when it's at idle, it makes knocking sound like diesel engine sound. but it goes away as soon as i accelerate or rev up the engine. i only hear at low rpm or idle..
this noise drives me crazy!! i feel so embarassed everytime i stop at a stop light...
but when the car is cold, i don't hear it... i would say after 5 minutes of driving, then i start to hear that noise from front of the engine?.. it's really hard to pin point where it's coming from...
please, i know there are some experts out there that can help me!!

thanks in advance!

 

how many mileson it? i had a pontiac that had alot of miles on it that was fine at start up, but after it warmed up at an idle you could here a knock from the crank.

 

If you have a steth it would help to pinpoint the noise. I would first check at the timing belt and see if it is slapping the timing cover. It would sound somewhat like the noise your describing. Also check the knock sensor and make sure it isn't shorted out and advancing the timing or if the catalytic converter might have come apart. Put the steth on the cat to confirm. Good luck and if you have any questions feel free to contact me. I've got 35 years exp. in auto repair. gmonk@pvtnetworks.net