2000 Chevy Cavalier Replacing Thermostat

Some cases a themastat can be put in backwards. When you put a thermastat in the spring side goes into the engine. Into the block As the water heats up it takes pressure off the spring, then the spring opens up the thermastat so the water can circulate. Air pockets form on the inside of the engine at times. Most of the time they work themselves out by running the engine with the radiator cap off and watch to make sure the fluid is circulating when it heat up. With the car running put the radiator cap on and then shut the engine off and letting it cool down. Make sure the resevoir is full. This works in most cases