I just installed a new 3.8 engine from a junk yard with 700 mile on it and have a real strange sqealing noise almost like a rollerbearing or belt squeal, which I have doen several checks such as removing belt to see if any tension pully or alt or water pump ect. making the noise but still continues. I have gotten under engine and noise sounds like it is coming from knock sensor area or buy ac compressor or the center of the engine block,this is where it is the loudest. I now a bit about motors and this is the strangest thing I have ever heard the engine runs great have put 700 more miles on it before this started, it only happens when engine is warmed up to operating temp and fades in and out at above 1000 rpm, trans is also been rebuilt at GM dealer under warranty. This isa head scratcher. Please help I am going crazy with this??? Edited by: ketchrace

 

if it is coming from the AC compressor, perhaps it is the belt at that point, or a bad compressor?

 

wondering how it canbe the AC compressor, noise still happens with engine running with belt removed so compressor is not rotating? only the crank shaft is turning at this time I have warmed engine up then removed serpintine belt and started engine and noise still happens I am beginning to think it may be my transmission which has been rebuilt three times at a local GM dealer. I now of nothing in the engine that can cause a load noise such as this it sounds almost metal to metal but will go away upon acceleration and as engine is decerlerated it returns for a short period until RPM is under 1000. Sound does not continue constintly fades in and out at idle. could this be my torque converter again or even trans pump?

 

is there any drivability issue? or just the noise?

 

Just noise vehical drives great but has had trans problems in the past year was in for warranty repair three times for hard shifting issue this was fixed prior to the engine change did not start making noise for approx. 200 miles after I installed the engine. Sounds like something rubbing metal to metal that type of noise but is not continuous goes away upon increased RPM and under 1000 RPMonly comes in and out does not last longer then a few seconds but extremly loud.

 

you asked this same question twice, I answerd the other one.