The chirping on my Marquis also goes away after a few minutes. I'm convinced it has to do with the cold weather. Belt loads are highest when the car is cold.... ps fluid is thickest, coolant has a somewhat higher viscosity, belt is least sticky. So if there is any weakness in the system, it'll show up on a cold start.

What puzzles me on my problem is the belt was replaced 3 yrs/16,000 miles ago.... too soon for belt replacement.

I figure only two things can go wrong with a tensioner -- the spring breaks or the bearing gives out. The spring should be easy to check. A bad bearing should squeal constantly -- right?

One thing I do whenever the belt is removed is that I clean the pulley grooves in a serpentine system. I notice a lot of crud gets built up in the grooves. I imagine it can push up on the belt and prevent full-grip engagement.

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95 E320 Cabriolet, 169K