I have a 1997 2.4L Cavalier, and it continues to overheat and lose coolant. It has been occurring more and more frequently and now is to the point that it is occurring every time I drive the vehicle. It was occurring less frequently before the reservoir was replaced, and the one that was replace had a crack in it, which seemed to answer both questions, but has caused it to overheat more often.
You could have a stuck thermostat. Has a mechanic looked at the car for the overheating issue?
Another possibility is cooling fans that are not working. Does it overheat in stop-and-go traffic, or on the highway, or both?
The cracked reservoir was likely the effect of overheating–not the cause of it.
The car needs to be checked right away by a qualified mechanic as there are several possibilities, and continuing to drive it will lead to destroying the engine.
The problem could be as simple as a bad thermostat or a problem with the heat sensor that activates the cooling fans. It could be a bad water pump or a clogged radiator. Or, it could be a blown head gasket.
In fact, it is possible that one of the simpler problems led to continued overheating and the continued overheating incidents could have led to a breached head gasket. The clue to this scenario is overheating that has become worse recently. The overflow reservoir might have cracked from the extra pressure that was introduced into the cooling system by a bad head gasket.
If you want to be able to salvage this engine, you have to resolve the overheating issues immediately.
Has the radiator cap been checked? If the cap is not holding pressure, overheating and loss of coolant would occur. Caps are inexpensive compared to the other possibilities. Regardless, have the car checked out by a mechanic.
Along with the thermostat I replace the radiator cap at each coolant change on my vehicles.