Coolant Reserve Tank (Overflow Bottle) for Nissan

This coolant reserve tank is a small but critical part of the engine cooling system. It stores extra coolant when the engine heats up and coolant expands . When the engine cools down, it helps pull coolant back into the system, keeping the radiator level stable and air out.

Why this part is needed

Modern engines run hot and need a controlled place for coolant expansion. The reserve tank prevents pressure spikes, reduces coolant loss, and makes it easy to monitor the level without opening the radiator cap.

How it works

As temperature rises, excess coolant flows through the overflow hose into the tank. After shutdown and cool-down, vacuum draws coolant back. The level marks help you spot leaks early ✅.

What happens if it’s broken

A cracked tank, weak cap seat, or leaking nipple can cause:

• Coolant loss and repeated low level
• Air entering the system (poor circulation)
• Overheating, heater blowing cold, or pressure problems
• Risk of head gasket damage if ignored

Compatible Models

• Nv350 Caravan
• Nv350 Urvan