Abstract: A valve in the flow aperture of a removable coolant reservoir enables coolant to flow between the reservoir and a coolant system while preventing the coolant in the reservoir from spilling when the reservoir is disconnected from the coolant system. A filling tube with a lower end and an air escape passage discourage users from overfilling the reservoir. Once the coolant level reaches the lower end, fluid accumulates in the filling tube, thereby indicating to the user that the reservoir is full. The air escape passage then gradually allows displaced air to escape and coolant in the filling tube to enter the reservoir. An overflow port and tube attached to the filling tube divert excess coolant away from the reservoir. A bleed tube, a bleed port, and a barrier in the reservoir remove bubbles from the coolant system and prevent the removed bubbles from reentering the coolant system.