On my first '98 C5 it would chirp when I first started and continue until you drove it for a while. Turned out to be the Top tensioner, but 6month later it returned when I was in CA, so I took it to J&D Corvette in Bellflower and they replaced the bottom tensioner and it went away and I never heard it again.
On my current '98 C5 which is a 4 owner CO car with 68,036 miles on it, the chirp started about 6 months ago. Figured it was the tensioners, but since it would stop after the car warmed up, I just put it off.
Well about 2 months ago I noticed that the Temp gage started showing half way between middle and red. Car never over heated, but it was like the cooling system had found a new center point towards hot. At this point I didn't want to guess one part at a time and because it also had that unrelated chirp, I drove it to the dealership. I had them change both tensioners; thermostate; water pump and the serpentine belt. $900 parts and labor after $200 club discount and the bird is gone that the temp is perfect.
I had them save me the parts so I could see the condition. The belt was severly cracked and needed changing and they said the Thermostat was also bad. Both tensioners had rough bearings so it was good I had them changed. The water pump looks good and spins freely and smooth. Chirp can be caused by a number of things and for that reason I satisfied with what I did...............and it's gone!
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God Bless, rick
'75 Steel Blue Stingray Coupe
'75 Hot Red L82 Stingray Convertible