What is the purpose of the coolant overflow plastic tank? Does it have to have coolant in it?
(2011-07-11 14:20:23) 1. Says: My overflow tank, or whatever it's called, has never had coolant in it. I have a 93 Ford van. I monitor the radiator and the radiator is always full. What do I need coolant in the overflow tank. If memories serves me, I think I put coolant in the overflow tank a couple of times, and it got spit out when the engine warmed up.2. Says: 1 is fact that the cooling system in modern cars is pressureized! This is because water under pressure boils at a higher temperarture,- with 50/50 antifreeze-water mix it is a little over 235 degrees (as opposed at 212) Your system has a pressure cap on it designed to release pressure at a certian pre-determined pressure (generally around 12-18 psi)... Water expands when it gets hot, -- so some runs back to reserve bottle where it is captured and saved! The entry from radiator is near the bottom of the bottle -- when the engine cools off, the water "shrinks in volume", - so water is pulled back from the bottle to replentish level inside radiator! This is designed to assure that the radiator remains "topped off" all the time!3. Says: When the engine is cold and hasn't been running for a few hours the overflow tank should be empty. When the car runs and it gets hot, the coolant gets hot as well and the fluid expands. The overflow tank gives somewhere for the coolant to go so that the pressure is relieved and you don't get a leak.If your engine is cool and there's coolant in the overflow tank, you have too much in the car and risk pressure failure.4. Says: like dogdin said,the small tank gets fuller when engine is running.when engine cools,it causes a partial vacuum,drawing water back into the engine. what no one is saying the canister should always be at least half full.the system will not over draw and it is a quick way to check the coolant level.5. Says: yes it does when car gets hot the motor takes from this tank to help cool it off Tag: What is the purpose of the coolant overflow plastic tank? Does it have to have coolant in it?