The most common reason a Chevy Venture overheats is because it is low on coolant. According to About.com, if the engine does not have enough coolant, heat builds up as the engine is unable to transfer the heat to the radiator, causing the engine to overheat.
Front-wheel drive engines have the engine mounted in a transverse direction, requiring the use of an electric cooling fan. If the fan does not activate, the engine is likely to overheat, especially in stop-and-go traffic. The fan pulls cooler air through the radiator. If its motor or the switch that activates it is faulty, the vehicle overheats when its speed does not force enough air through the heat exchange fins.
Gasoline engines use thermostats to help them reach ideal operating temperature. Once the engine reaches this temperature, the thermostat opens to allow coolant to circulate through the radiator. If the thermostat sticks, the Chevy Venture overheats.
If the vehicle has over 50,000 miles, the problem is often inside the radiator due to a build-up of sticky material. Flushing the cooling system and refilling with fresh coolant each year helps prevent this problem.
Continuing to operate an overheating vehicle may cause serious mechanical problems. If the gauge or warning light shows a problem, move the vehicle to a safe spot on the side of the road, and turn off the engine.