I am at a dead end with this and now getting worried. Here is what happens. On hard aceleration the car sounds like a tank. The noise that occurs compares to what might sound like an exhaust problem. When you give the gas slowly all sounds fine, but hit it hard and BAM!! This used to sound like this when she was cold, but now it's all the time. I also hear a shhhhing noise (what you might hear if a tire has a flat spot) it gets faster as you increase speed, but does not get any louder. It appears to be coming from the drivers side rear, but I can't say for sure. I don't know if they have anything in common or not.
I had a rebuilt put in a year ago along with a rebuilt tranny. The tranny has shifted somewhat sloppy (for my taste) but the mech. said all is good. I just had the oil changed by the same shop that did the engine and pointed these "noises" out to him, but he came back with an all "OK" could not find anything wrong. The car did not do this after the engine was put in so I ruled that out. There are no current codes and the ones I cleared were nothings. She's a 99 DeVille. Someone out there has had to gone through this and knows what I should do..
PLEASE HELP !!!!! [sm=dontgetit.gif]

 

well the one sound yer hearingong on teh drivers side sounds kinda like teh bearing, as for it "sounding like a tank" meaning is it really loud? from your description it sounds like the exhaust is opening up as yer engine torques foreward, so in that case i would suspect either a bad engine mount allowing the engine to travel farther forward and crack the joint between the rear manifold and the rest of the system open, or one of your spring bolts could have broken , or the gasket there has broken, but if your leaking onr acceleration i would definately suspect that joint.

 

you gotta tell the guy to get in the car and take him for a ride and make sure he hears the sounds.
sitting in the cozy shop wont do it.