Keeping Cool in Summer It is not uncommon for me to receive questions from customers concerning the operating temperature of their Vette during the summer months. For the most part, Chevy engines are designed to run up to around 240°. In fact, some late model fuel injected cars have cooling fans not designed to kick in until about 230° (unless your A/C is running). This is mainly due to the desire to keep emissions down. During hot weather do not be surprised to find your carb’d mechanical fan Vette running in the 215°-220° range in slow moving or stop and go traffic & for later models this may get as high as 230° or higher with A/C working. When you start moving this temp should go down but may still hover around 200° for late model cars. Still think your car is running hot? Assuming the gauges are working properly…… If it runs hot or overheats while idling check these items: Coolant - Check the coolant level and quality. The mix should be 50/50 coolant and water. Belt - Make sure the water pump belt or serpentine belt is tight. T-stat - Start the car cold and monitor the temp gauge. When the temp reaches the thermostat opening temp (usually between 160°-195°), the upper radiator hose should get hot. If it does not you may have a stuck t-stat. Fan - Make sure the electric fan comes on at the specified temp for your car and when it comes on that it is turning in the proper direction. For mechanical fans make sure the fan shroud is installed with the proper seals and fan clutch Radiator & Cap - Check the radiator and make sure it is not blocked with debris in the front. Check the cap and cap seal; take it to a shop and have it pressure tested. Hoses – Check your hoses to make sure one has not collapsed and that they are not hard or feel spongy Air in coolant system – If the car has required service recently in which the coolant has been drained there is the possibility air may be trapped in the system. You may take it back to the shop that did the work. This is more an issue with earlier C4s. Car runs hot when moving? Check points above. Airflow – Make sure you are not driving too closely behind traffic. Keep some distance from the traffic in front of you to help airflow get to the radiator. Drag- Make sure the parking brake is not engaged or other drag is on the vehicle. Engine Tune- Check the ignition timing and make sure the ignition is not too advanced. Also, an overly lean motor (not enough fuel) may cause the engine to run on the hot side. Engine damage – A bad engine cylinder head gasket can also make an engine run hot. Although this overheat can occur from idling, most customers experience this when driving. If this is the case, get it to a trusted repair shop and they can determine the cause. If you feel you have a bad cylinder head gasket DO NOT DRIVE the car. The cylinder head can be warped, especially if it is an aluminum head. **If your car is overheating consistently get it to a repair shop. Do not drive it as further engine damage may occur** One of the inherent cons of driving the Vette in the summer is the heat. Big motor, small cabin, close proximity to the engine and transmission can all lead to “warm” driving in the summer. I know since my ’85 will quickly get hot in the summer. To remedy this and keep the car running cooler and me as well, I have installed a temperature switch ( in the Heavy Duty Cooling switch position) which closes at 200° and opens at 185°. I then wired this to the ground side of the cooling fan relay coil. When the temperature reaches about 200° the fan turns on and when it gets to about 185° it turns off. This would be an easy conversion for even non-computer cars and cars with mechanical fans. In fact, you can remove the mechanical fan and free up a bit of horsepower. Keep Cool!!! And Drive safely!! Check out usmracer.com for more information or contact rob@usmracer.comor greg@usmracer.com.