95 Lesabre engine noise.

I have 95 Lesabre that has a engine rattle at idle only. If you increase rpms at all the rattle or knocking like noise silences. If you take off the serpintine belt the noise silences. So at first I thought it was the alternator, but wasn't, then the waterpump, wasn't. I have a stethescope. It seems the noise is coming from the crank pully area. Really behind it. Anyone experience anything like this. It is quite with the belt off. I just assume it must be an accessory, but I guess not. Any suggestions.

The crank pulley is actually a harmonic balancer. It's fairly common for the rubber to dry out & crack. This will cause the two metal pieces to clank together when idling.

wouldn't the noise continue when the serpentine belt is off. Also What two pieces of metal on the crank pulley and can I see them. Tahnks

The balancer is actually in 2 parts... The front and rear parts, makes no sense I know....

The part that the belt rides on is held in place with a breaing of sorts, the rubber part of the balancer will stretch depending on load, this helps absorb pulses from the ac when the clutch cycles on and off, makes for smoother operation...

You need to check and see if the rubber is cracked or split, push on it and see if there are any breaks... if there are breaks the stops on the back of the balancer can make a god awful racket...

With the belt removed, see if you can rock the outside of the balancer back & forth (clockwise-counterclockwise) by hand.

BINGO! Thanks for all the help. The rubber is cracked and with the belt off I can rotate the pulley back and forth, almost simulating the same noise. Thanks for all the help.

Make absolutely sure you get a 95 L27 Balancer... 95 is very one off and is the only unit thats proper for your engine..