Engine Coolant Thermostat Assembly for Infiniti/Nissan — Stable Temperature, Strong Performance ️

Why this part is needed

Your engine must reach and hold the correct temperature to run clean, efficient, and powerful. This thermostat assembly regulates coolant flow so warm-up is quick, emissions stay low, and the heater works reliably in cold weather ❄️. It protects the block, heads, and turbo (if equipped) by avoiding thermal stress.

How it works

Inside sits a wax-pellet actuator. As coolant heats, the wax expands and moves a plunger that opens the main valve. When cold, the valve stays shut, recirculating coolant for fast warm-up. At operating temp, it opens progressively, sending flow through the radiator. Result: steady operating temperature, smooth idle, and consistent fuel economy .

What happens if it breaks

• Stuck closed: rapid overheating, boiling coolant, loss of power, risk of warped head or blown gasket.
• Stuck open: engine overcools, poor MPG, weak cabin heat, rich mixture, possible check-engine light.
• Leaky seal/housing: coolant loss, hot spots, air pockets, water pump noise.

Tech tips

Install with a new seal, clean mating faces, torque evenly, refill with the correct coolant, and bleed air. Afterward, confirm fan cycling and stable ECT readings.

Compatibility

• Qx50/Ex
• Q70/M
• Qx70/Fx
• M