Questions and Answers
Corvette Having Hot Flashes
Q. I have a 1986 Corvette that is overheating and not blowing hot air when the heat is turned on. I have replaced the thermostat and now the problem starts and stop off and on. Could it be a block in a line? The lines into the firewall are both hot please help if you can.
A. If the overheating has stopped but you are only getting heat inside off and on, then I would say the problem is in the heater doors in the dash. The fact that both heater lines are hot is saying the coolant is flowing through the heater core and the heater control valve is working.
If it is still overheating, I would try another thermostat, a 165 or 175, and see if that takes care of it. It's possible you put a defective thermostat in. If it still over heats, then you will need to take it to a radiator shop and have a reverse power flush done to make sure the block and radiator are clean and flow is not being impeded.
It sounds to me like you have two distinct problems here, and the no heat and overheat are not related.
