I have a 96 z-28 camaro convt. that is getting up to 235-240 degrees and I don't know why. is this normal? it happens when I'm in stop and go traffic, but on the highway it runs at 180 degrees. I have put a new thermostat and water pump in and flushed the system.

I think that your car has an electric fan. Do you know if it is turning on? It sounds like you have an airflow problem. Make sure that your fan is turning on at around (I believe) 190 degrees. If it isn't, I would check the thermostat switch and the relay. Also check for any obstructions that might prevent air from getting to the radiator.

The fan is kicking on sometimes, but sometimes it doesn't and then it get up to about 235 240 degrees. What part would it be? sensors? switches? or the relay? And again sometimes it comes on but sometimes it doesn't but more often it doesn't.

I were to guess, and this is only a guess, I would say that either the thermostatic switch or the fan relay is going bad. The first thing that I would do is check every connection that you can in the electric fan circuit. You might get lucky and find a bad connection that just needs to be tightened or cleaned. A good shop manual for your car should have all of the electrical schematics that you need to diagnose the electric fan circuit.

Since your problem is intermittent, you won't be able to reliably test either component unless there is something obviously wrong with them. About the only way to check either of them is to replace them, one at a time, with known to be good components.

There is also the possibility that the fan motor itself is going bad. Again, check for obvious signs of damage. If everything else fails, you may have to replace the fan motor.

By the way, when diagnosing problems by replacing components that might be bad, it is a good idea to buy them from a parts store that will give your money back if you find out that you don't need them. Good Luck.