You could possibly have a circulation problem, or a over heating problem. Need more info.
The overflow tank for coolant will "boil" if there is air getting in the coolant chamber. This can be a head gasket going bad.
you add it in the expansion tank located at the front left when facing the opened hood - its the white / clear plastic tank with a metal cap on the top of it. only open the cap when the engine is cold or it will boil the coolant and cause it to spurt boiling coolant (water) all over you and you car's engine.
when the engine is stopped, the coolant stops flowing. The coolant inside the engine can boil and force coolant into the expansion tank. this is normal.
put coolant into my over flow car was running hot and the coolant erupted like a volcano on the side of the over flow
The car normally pushes it out the over flow.
When all the coolant in the radiator and coolant tank heats up the volume will increase and force it's way through the weakest point which would probbaly be the cap on the recovery tank - if you have filled the recovery tank to the maximum you had better take half of it out.
Probably low coolant.
it sounds like your coolant over flow tank is leaking. it is a common problem with these cars. might also check your radiator for leaks or your exhaust for coolant, but if there is coolant in your exhaust that would mean blown heads
Add coolant to the coolant reservoir tank (a rubber tube runs from the top of the radiator to the coolant tank). The system is designed to automatically purge itself from air and replace it with coolant from the coolant tank. Watch the level of fluid in the tank and make sure you keep it filled to the "full" mark. If there is air in the system, you will notice the coolant level in the tank drop over time as the radiator draws in coolant and purges itself and the rest of the cooling system of air. Expect this to occur over several driving sessions. The cooling system is a sealed system; you can add coolant directly to the radiator when your vehicle is cold (if there is room), but NEVER when it is hot. It's best, however, to be patient by adding coolant to the reservoir tank and letting the system take care of itself.
no cap, there is only a cap on over flow coolant tank. to add coolant add to tank make sure it is at the right level when cold.
i have a 85 fiero gt. i had the same problem. the coolant would boil out of the coolant tank. turns out the thermostat was bad. it cost me 20 dollars at autozone and was easy to replace. hope this helps
Oil in the coolant tank indicates a head gasket leak.