i've recently noticed a rattle/knock coming from the front of my engine while running. i believe it to be the belt tensioner. my question is: is there supposed to be any 'back-and-forth' movement of the pulley? while the engine is running, the pulley is moving back and forth slightly. the pulley seems to be rotating ok, but it moves back and forth some and makes a small rattle/knock; moreso when the a/c is on.
the belt was changed approx. 3 months ago (approx. 5k miles).
thanks for any input. also, if it needs to be replaced, does anyone have the part no.? i've check at a few dealers for prices, but none will give me a part no.

 

I had to replace mine Friday. I believe it's a dealer only item, and mine ran me $40.10 after tax. Mine used to rattle, then all of a sudden, it just went out. If you suspect it's goin out, I'd replace it, otherwise you might end up buying a new belt too.

 

i forgot to add.........it's a 1992 rs, 3.1 v6.
thanks

 

92 Bird 3.1, so it'd be the same.