Engine Coolant Expansion Reservoir (Overflow Tank) ??

This coolant reservoir is a critical part of the cooling system. It stores extra coolant as it expands with heat, then feeds it back when the engine cools down. Without this buffer, the system can’t keep a stable coolant level, and overheating risk rises fast.

Why this part is needed ✅

Modern engines build pressure and temperature quickly. The reservoir provides a safe space for coolant movement, helps maintain correct pressure balance, and makes it easy to monitor coolant level during service.

How it works ⚙️

As coolant heats up, it expands and is pushed into the tank through the overflow line. When the engine cools, coolant is drawn back into the radiator, keeping circulation steady and preventing air pockets that can cause hot spots.

What happens if it’s broken ❌

Cracks, weak seams, or a leaking neck can cause coolant loss, low level warnings, overheating, and poor cabin heat. Air may enter the system, leading to unstable temperatures, gurgling sounds, and possible engine damage if ignored.

Compatibility ?

• Cx-9