Drove from Tucson to Phoenix, Everything fine until temp went over 230, guy I bought it from swares that Chevy dealer said this car runs ok around 230, no way! The water was boiling and the Corvette had major problems going into stop and go traffic. Barely made it home. Probably need to change the MAF sensor for the fuel problem and then the Thermostate or Water Temp Sensor has recently been changed, so I guess the Radiator or water pump is glogged. What do you C4 owners know to tell, me.
This is my 2nd Vette, had a 1981 in 1984.

 

Water boils at 212 degrees but running a 50/50 mixture of water and antifreeze along with a good radiator cap will raise the boiling point of your coolant to around 250 degrees or so. Mid America and Corvette Central sells a kit that will turn your cooling fans on before it pegs out the gauge like that. I'd definataley check your radiator and water pump since you're concerned with them. I recommend starting with just some basic cooling system maintainance. Do a flush and refill, check for debris and trash in front of the radiator, and verfy proper fan operation. Keep us posted. Good Luck!!!

 

You don't say what year C4 you have, the cooling system on the LT-1 and LT-4's are very different than the "normal" style cooling flow of the earlier C4's. On the '92 to 96 with the A/C off, in heavy or stopped traffic, the cooling temp can get downright scary. With the A/C on, the second cooling fan brings the temp right down. I agree, the first thing to check is what is in the cooling system. If it is a late model C4 be careful of the filling and bleeding procedure, it is a reverse flow colling sytem and behaves very different from the earlier models.

mark

 

Water under 16lbs of pressure boils at a higher temp than 212. More like 240. Need to check cooling fan operation, sounds like to me either the t-stat is bad or water or air flow to the radiator is not very good.