[97CobraNow]

My engine sounds horrible at idle. like a diesel. i run 5w20 oil. and its full. sounds like its coming from under the intake manifold. kinda of sounds like a rotational noise. when i rev the motor via the throttle body as im standing over the engine, once the engine reaches a high enough rpm, the noise goes away and all you hear is a solid engine. when the rpms drop back down, you hear the noise pick back up. like it wasnt there at high rpm at all it went away, and came right back as soon as the engine slowed down enough. at idle it sounds likea diesel. horrible. please help

[97CobraNow]

It sounds identical to this 99 cobra video.

YouTube - 99 Cobra Knocking

YouTube - 99 Cobra Knocking

[97CobraNow]

i can hear the noise all over the engine. it resonates through the cylinder heads, intake manifold, block, timing cover. i just talked to someone on svtperformance forums and he said that he had the same problem after he did a underdrive pulley swap. This problem came right after i just did my pulley swap with new harmonic balancer. he said that he used too much sealant in the key hole, and that it did not alway the balancer to set tight enough and allowed the sprockets behind the timing cover to hit eachother and produce the noise. heres my video taken with my blackberry. you cant hear everything, but you can hear the noise. i think the previous video of the 99 cobra is a better respresentation. like i said, the noise goes away at high rpms and kicks back in one the rpms drop, and sounds like some kind of rotational noise.