Cooling system issue

[93ToyCorolla]

I don't understand why I was low on coolant yet the overflow bottle was above the max. I thought when the radiator goes low it draws in the coolant from the bottle????????????

[Aussie_Camry]

It does... but you need pressure in the system for it to suck the overflow coolant up!!! Id suggest changing your radiator cap (if you have the V6 I know this has two caps one for radiator one for water inlet, change both... its inexpensive)... this could be the source of pressure leakage meaning the system doesnt have enough to suck up coolant when it goes down.

[marc780]

How low is low? The system's designed to suck back in the coolant as you know, but this occurs through the heating and cooling of the engine when you shut it off - too many short trips in cold weather or something?
If you only added a few oz of coolant to the radiator it is probably normal - but what he said, change your radiator cap. Also blow water or something through your overflow tube to the bottle to check its not blocked or leaking.