Hot 91 Corvette



have a 91 Corvette that heats up on ocassion. Nothing was found to be doing this, everything checked out ok. So my thinking was that I use octane booster, only as advertised. Another Thought was the oil is as clean as it comes out of the can, never has it gotten dirty. This is only a weekend car appox.2000 miles per year… It runs very very good probally too good. I do on ocassion run it pretty hard however that is not when it heats up. Any suggestions. No Im not buying a Gremlin for the weekends.


More info is needed.
Heats up during city driving, highway driving, or both?
Heats up only when the A/C compressor is engaged? (A/C or DEF position)
Any loss of coolant, bubbling, etc.?
Slightly overheats or seriously overheats?


usually when above 85 90 degrees as long as it is moving its ok. If I get stuck in traffic it will start to clime, or when in the drive just ideling 40 degrees just to charge the battery.


EVERYTHING is OK? Tell us what al has been checked.

Does the electric fan kick in when it gets hot? If not, it may have a bad sensor, bad fan motor, or break in the wiring to those items.


I would suspect either the cooling fans are not working properly or the radiator is clogged up.
You might check the radiator and see if it has a brownish colored sludge in it. DexCool coolant can do this so flushing and refilling could cure the problem without a radiator replacement.

Your comments lead to the fan not coming on, but there are other possibilities as noted in other responses.  

I will make one comment even if it is very unlikely to be involved with this problem.  That oil ...  If it is in there for over 2,000 miles it is too long.  It needs to be changed on time or miles whichever comes first.  The same can be said for coolant and if that has not been changed regularly that could be the problem.


Chevy garage kept car for a couple days trying to find the problem. Fan is working coolant is not discolored thermostat is working it is not loosing coolant. Everything that can be checked was checked and turned out OK. Guage was also checked. Radiator was cleaned with new coolant added. Climes to 240 250 degrees.Guage goes to 260.


It should be easy to trouble shoot this problem if you can get it to overheat while idling. Use an infrared temperature gun to read the temperature of the engine outlet fitting, the inflow radiator tank, the core temperature at various points, the outflow radiator tank, the water pump temperatures, ambient air temperature, and air outflow temperature. If the outflow tank temperature is less than 20 degrees Farenheit below the inflow tank temperature or the outflow air temperature is less than 40 degrees higher than the ambient air temperature, you have a heat transfer problem with the radiator. The heat is not getting from the water to the fins to the air. If there is a large temperature drop from inlet tank to outlet tank, you have a flow problem or a heat transfer problem in the engine.

From your description of the symptoms, there is not enough air flowing through the A/C condensor and radiator to handle the heat being produced at slow speeds which points toward the cooling fans, shroud, airflow path, fin blockage, or maybe debris on the face of the condensor.

Let us know what solves this problem for our reference.