I just had my coolant system flushed and filled, and now I'm a little confused as to how the system works. My Haynes manual says "The coolant reservoir does double duty as both the point at which fresh coolant is added to the cooling system to maintain proper fluid level and as a holding tank for overheated coolant." So if everything is working properly and my car is not having overheating issues, then there should be NO coolant in the reservoir, right? I would appreciate it if someone cleared up this for me. Thanks!

Peter

 

Someone told me that the reservoir should always be at least 1/2 full or 1/2 empty which ever you preffer.

 

The reservoir does act as the manual says. It "pushes" out antifreeze when hot and all the various liquid and parts are hot (expanded) and "draws" in fluid if "low". So, you should just look at the reservoir - it has a cold line and hot line. Fill to that level.

Make sense?

 

The tank has Min and Max level marks for the coolant level. There should always be coolant in there. When it looks brown and dirty the system, including the tank should be cleaned out. They were once refered to as expansion tanks. When the system got hot fluid would go into the tank, and then be sucked back into the radaiator when it cooled.