well, lets see if you guys can help me with this...I've got a '91 Formula, 5.0 T.B.I, automatic, and I've been having this rattling noise at low r.p.m's only, after the engine warms up (mostly at idle)...when you step on the gas hard enough, it clears right up.

when im in park, thats when its the loudest...when i shift into drive or reverse, it gets quiet again. if i have the A/C or heater on, once again, the rattling stops or quiets down considerably.

it sounds like its coming somewhere from right behind the pulleys, in the water pump area. i have replaced the belt, tensioner pulley, and checked rest of the pulleys...nada.

to give you a better description of this noise, when i pull into a car wash, my car almost sounds like a large diesel truck (due to the echoes)

any advice would be greatly appreciated

 

You can pinpoint exactly what is making the noise - JUST BE CAREFUL! Take a long screwdriver, put the handle end against your ear, and put the blade end against various engine parts. The vibrations will transfer through the screwdriver, vibrate your eardrum, and are very loud in your ear. Really helps pinpoint exactly what - you'll really know when you hit the right spot. I have also taken the antenae off and used it, it's very long and works great. You just have to BE CAREFUL that you don't stick a moving part, or jam the thing in your ear! Places like Harbor Freight sell auto stethescopes for like $5 too - but when in a pinch, the antenae works wonders.

 

Thanks, I'll give it a try

 

sounds like an exhaust heat shield.

 

I was about to say what flyit said.. i'd check any manifold heatshieldes and heatshields on the cat, I had a heatshield on my cat break loose and make horrible noise..

 

mine does that too, the vibration i mean... its exhaust hitting random parts.. trans cooler lines, exhaust manifold heat shield... just make sure everything is tight on the shield and seperated down below and it will stop