screeching engine

[usedcar129]

I have a 92 SC400 and I have a screeching noise coming from the engine. It is really loud. When I rev to 2000rpm the noise starts. I have replaced the belt, various pulleys, I have a new alternator and new power steering pump. I think the noise is coming from the front of the engine because I have taken off the belt and started the car and the noise disappeared. I have gone to 3 mechanics and none of them have been able to locate the origin of the noise. Also when I apply dressing to the belt the noise goes away for a short period of time but always comes back. Sometimes it comes back in 5 seconds other times in a minute. If anyone has any suggestions please let me know.

gm used cars

[A2V]

is it same with high squeel sound?