Thermostats, Thermostat Housings and Fittings

The correct coolant temperature is a crucial factor for the proper functioning of any car engine. Overheating can lead to serious and costly damage, making efficient coolant circulation vital. One of the most important components of this system is the engine thermostat, which, although small, plays a significant role in maintaining the optimal operating temperature. At EuroFrance, we stock a wide range of new thermostats, housings and fittings for popular brands such as Renault, Peugeot, Citroën and Nissan.

How Does a Car Thermostat Work?

The main task of a car thermostat is to control the circulation of coolant within the cooling system. When the coolant temperature is below approximately 203 °F (95 °C), the thermostat remains closed, allowing the engine to warm up quickly - this is known as the short circuit, where the coolant flows only through the cylinder head and engine block. As the temperature rises, the thermostat opens, directing the coolant to the radiator, where it can be cooled by up to 20 degrees. Once the temperature stabilises, the thermostat closes again, restoring the short circuit and ensuring optimal engine conditions. This prevents the engine from overheating or running too cold, which affects its longevity and efficiency.

Construction and Common Failures

Car thermostats are simple yet essential parts. They consist of a bellows and a poppet valve enclosed by a thermostat housing. This creates a sealed system that rarely fails, but when it does, diagnosis and replacement are quick and relatively inexpensive. The most common failures are the thermostat being stuck open or closed. If it remains closed, the engine may overheat and boil. Conversely, a thermostat stuck in the open position prevents the engine from reaching its proper operating temperature, resulting in increased fuel consumption and poor performance. To check the thermostat's functionality, simply remove it from the system and immerse it in hot water - no reaction indicates the need for replacement.

Thermostat Housing and Outlet - Essential Cooling Components

The thermostat housing assembly and thermostat outlet also play crucial roles in the proper functioning of the cooling system. The housing ensures a tight seal and proper positioning of the thermostat, while the outlet allows for correct coolant flow between the radiator and engine block. Wear or damage to these components can lead to coolant leaks, often visible as intense leakage from under the bonnet.

If the outlet or housing fails, stop driving immediately and seek roadside assistance to avoid severe engine damage.

Replacing these parts is quick and restores full cooling system functionality.

How to Choose the Right Thermostat

Selecting the correct cooling system thermostat depends on your vehicle's make, model and engine type. You can filter our catalogue by brand - including Renault, Peugeot, Citroën, Nissan, Dacia, Opel, Fiat and Volkswagen - as well as by model (Megane 3, Scenic 3, Clio 4, 307 and many others) and manufacturer. If you are unsure which part fits your vehicle, use your VIN or original part number to find the exact match.

Thermostats and Parts at EuroFrance

At EuroFrance, you'll find a broad selection of car thermostats, housings and outlets from manufacturers such as PSA, Dacia/Renault and DENSO. Our primary focus is on new thermostat parts backed by a 12-month warranty, though used alternatives are also available with a 30-day warranty. With over 25 years of experience, we provide expert advice to help you select the right components for your vehicle - so your engine operates under optimal conditions and you avoid costly repairs on the road.

Choose reliable parts from our range and keep your car's cooling system in top shape. For more cooling components, visit our engine cooling category.