I have a 1998 Buick Ultra with aproximately 65k miles. It runs
great but at idle while in gear at a stop light, there is a noise which
is hard to describe except to compare it. It sounds like a
mixture between a diesel idling and the valve noise older 4 cylinder
motorcycles made in a very low idle. This only occurs when the
the vehicle is warmed up and idle is below 700rpm at idle in gear.
I just changed to Mobil 1 oil to see if it was valve
related and there is no change and it may be louder (of course I am
listening very closely now). Above idle no noise and performance
is not affected nor gas mileage (still around 27 28 on the highway).

I have heard the pulley on the supercharger may be the
culprit. Any help will greatly appreciated as I don't want
expensive repairs later if a little maintenance now can prevent it.

someone told you that the pulley can be making a noise? im curious as to what they told you can be wrong with the blower pulley.

smileys/smiley16.gifI hear the same problem, I have a 97 3800 SC series II in a 1988 Fiero GT, the engine is turned 180' so the rear is at the front. The noise i hear sounds like its coming from inside the valve cover, i checked and replaced the EGR so it not it. Its definetely not the supercharger. I f you ever find out it will save me time looking.

there is really no way that a pulley can make a noise, unless the belt is slipping...