While chasing a slow cooling system leak I've the the need to drain and refill my radiator three times (that another story). Each time following established guidelines. when my thermostat opens after getting hot enough and while watching the coolant with the radiator cap OFF I always get overflow out of the radiator all over the shop floor. It's more like an eruption. How can I avoid this overflow? I'm going to install a new radiator and would like to avoid the mess again. On most cars the flow starts and bubbling is witnessed below the neck of the radiator. But this car belches up and out. Any help would be appreciated. My car is the 96 Geo Tracker 1.6. New hoses, clamps, and thermostat that is recently new and running fine for the passed 6 months.