I have an 1987 RX-7 GXL, It's my daily driver. I used to have problems with radiator caps spewing out all my coolent, then when I switched them out and put an exhast on it (it was straight piped), I now have the over flow bottle cap bursting off and the water is boiling inside it and spewing everywhere, is the car overheating? I've been trying to fix my temp. gauge but that doesn't work at the moment.

 

can't say for sure if it's overheating or not, but it does sound likely that it has though. could be as simple as a wrong/bad radiator cap or as complex as a broken water seal.

 

Take the rad cap off.
Start the car.
If the coolant gushes out,you are toast.

 

Turns out that the guy before me took out the thermostat and never put in a new one back in. I put one in and it did it still. I switched out my radiator caps and it stoped spewing the water everywhere and it's not boiling in my overflow bottle after I ran the car hard. I checked it perioticaly with an infared temp gun and on top by the spark plugs it read 236. I'm not sure if thats normal or not.