when i turn on my car i hear this annoying buzzing sound of "add coolant" when i accelerate it turns of well when he wants he goes off, I check the radiator and is full, check the coolant box and is was empty!!! but i wanna it to ask you, theres two littles things to put coolant (i think) one is in the back at the end of the engine i provided a pic, and the other one beside the radiator i dont know where to put the antifreeze or if i have to put 50/50 water and coolant in on of them
i heard from a friend that used to own an rx7 that your suppose to put 100% antifreeze in the little box thats at the end of the engine(not the one beside the radiator)
i have a RX-7 88 GXL
thank you
i post pics

 

have you checked the oil level yet, as the same buzzer used for coolant is used for the oil level (and redline).

If it is not the oil level check the oil level sender.

BTW, if it is (as I suspect and you have forgotton to check) your oil level you are at least 2 quarts low and on your way to buying a new motor.