I understand the theory of the system, but the previous owner changed the cap to a type that has a red pressure relief valve. This valve seemed to leak coolant rather than allow flow through the hose to the recovery tank. I have since replaced it with a conventional radiator cap. When I check the level in the expansion tank it is always down a few inches which tells me coolant is not transferring between tanks. I have removed and cleaned both tanks and installed new hoses, even reversed forced air in the recovery tank over-flow hose to verify coolant flow. Do I still have the wrong cap?
Thanks.
quote:
Originally posted by jack deryke:
Your car needs an overflow tank to work properly. When the engine heats up, the water expands and no longer fits in the cooling system. So the radiator cap opens and allows the excess water to expand into an overflow tank. When the engine cools off, a partial vacuum is created, the cap again opens and water is sucked back into the cooling system from the overflow. Without such a tank, your cooling system will lose water each time you drive, and about the 3rd or 4th time, it will overheat. The overflow need not be a stock tank, but if its plastic, shield it from header heat, or it will melt. This happened to me in a 50 mile drive.