Mazda: 99 protege sedan, radiator fans, radiator cap

Question
I wanted to ask what might be causing my car to over heat and flush the antifreeze into the reserve cantainer and out of there onto the ground. I have changed the thermostat, water pump, and radiator. I tested the cylinders and each one is at about 160 psi. I hope to here from you soon.

Answer
After starting the car, how long before the water in the reservoir starts bubbling? If the water in the reservoir starts bubbling before water is actually hot, then you may have a cracked cylinder lining, cracked head, or a warped head /  bad head gasket. I see that you already did a compression test, and that will help determine whether or not the engine is damaged in this way, but it can not be relied upon by itself. If the engine is damaged, and with the thermostat installed, the water in the reservoir will not start bubbling until after the thermostat has opened. Pressurizing the radiator with a pressure tester will also help you to determine if your motor has sustained this type of damage.

A radiator cap that does not maintain sufficient pressure can also cause water to overflow the reservoir. It can also cause the water to boil at a lower temperature which greatly diminishes the coolant's ability to keep the engine cool.

You have probably already looked into this, but make sure that the radiator fans are coming on. If the fans do not come on, then they are very likely the cause of the problem, However, if the coolant reservoir is overflowing due to engine damage or a bad radiator cap, then the fans will not come on. This can cause a person to misdiagnose the problem.