Hi all im new to this thing. I have a 1991 toyota soarer uzz30 v8. The car overheats every few days. The engine light comes on and steam comes out of the resevoir does dat mean it's got a cracked head?? i pull off the bolt on top of the thermostat and full it up with water. It takes over 4l of water at times. after that it's sweet for a few days then it does the same.Do u have any ideas?