What does a coolant expansion tank do and do I need one?

For our Question of the Week this week, we are taking a look at the Subaru cooling system, specifically the auxiliary tank on the intake manifold, and the expansion or overflow tank on the radiator. These are two small components of the cooling system that are often moved around, and sometimes people even consider downsizing, or removing them all together. We wanted to take a look at what both of these tanks do, and talk about how important they actually are. Here are some topics from the video: 00:00 - Intro to our Question of the Week 00:30 - What is the Coolant Expansion tank? 00:53 - What does the Subaru Auxiliary coolant tank do? 02:59 - Can you remove the Subaru Auxiliary coolant tank? 03:35 - What does the Coolant Overflow tank do? 06:10 - What does it mean if the Coolant Overflow tank overflows? Thanks for watching and Stay Tuned!