LittleBill wrote:

Andy-
1. It happens in stop and go traffic / low cruising
speed.
2. If I get it above 35-40 yes, it cools down.
3. It happened half way through the cruise- cruise was
approx. 10 miles- take or give a few miles. In and
around Coopersville.
This is fairly normal with the exception of your fans not coming on.

4. Can't hear the fans kick on until in the hash marked
area of the gauge. What's that 230 degrees or more?
Use the digital gauge on the dash, the analog gauges are usually off. And watch the fans in the driveway.

5. Will go out and look now around radiator for debris.
6, I am assuming it is original radiator- car has 61,000 miles on it.
61k shouldn't be a problem but if you don't know when the last flush was, it needs to be done including pulling the knock sensors.
7. Had the Vette in the driveway Sat. and turned it on ,
left it idling to see what happens- approx. 3 min.
later I have a temp. gauge that is almost pegged.Did
not hear fans kick on. Bad relay? Switch?

8. Have purchased a new thermostat and will put that
in. No coolant is being lost or seeen on the garage
floor or ground. No bubbling sound
If it's cooling down when you get back up to speed, it's probably not the T-stat. You can put the new one in though, Note that the bleeder that pianoguy mentioned is on the T-stat housing, Open it using a screwdriver,