No problem I drink,
The radiator cap actually increases the boiling point of your coolant by about 45 F (25 C). The same way a pressure cooker increases the boiling temperature of water so does the cap. The cap is actually a pressure release valve, and on cars it is usually set to 15 to 16 psi. The boiling point of water increases when the water is placed under pressure.
When the fluid in the cooling system heats up, it expands, causing the pressure to build up. The cap is the only place where this pressure can escape, so the setting of the spring on the cap determines the maximum pressure in the cooling system. When the pressure reaches 15 to 16 psi, the pressure pushes the valve open, allowing coolant to escape from the cooling system. This coolant flows through the overflow tube into the bottom of the overflow tank. This design keeps air out of the system and is what they call a sealed or closed system. When the radiator cools back down, a vacuum is created in the cooling system that pulls open another spring loaded valve, sucking water back in from the bottom of the overflow tank to replace the water that was expelled. By increasing the pressure of the cap, will cause the pressure to increase in the system and if set too high, a lot of times will cause another part of the system to blow out,like a weak hose or a weak spot in the radiator. Older systems didn't have the overflow tank and would spill over onto the ground.
To see a demonstration on how a
Closed Cooling System Works, CLICK HERE
Now on older systems, if you have a weak cap, the same happens except that the water can boil out easier causing a low water condition and looking as if you have a radiator leak since it cannot recapture the over flowed water on the ground. If you have low water in a radiator every few days or so, do a pressure check on the cap to ensure it still is releasing at the 15-16lbs of pressure it is rated at.
