Mercedes Engine Coolant Thermostat - Hella 354777921

Product Information

Thermostats are a simple device which regulates coolant flow through the engine. When cold it will stay closed, stopping coolant flow and helping the engine warm up faster. Once up to temperature, it will open and allow normal coolant flow and maintain proper engine temperature. Always install with the 'jiggle pin' bleed valve at 12 o'clock when possible.

For many applications, multiple temperature ratings are available. These ratings denote when the thermostat opens, and in extreme climates different temperature ratings can be used to assist the vehicle in maintaining proper temperatures. In very hot desert climates for instance, a lower temperature rated thermostat may be preferred.

There are two types of thermostat failures:

Thermostat stuck open (most common): Coolant will flow through the engine constantly from cold, preventing the engine from reaching operating temperature. Usually this means a rich mixture resulting in poor fuel mileage and potential catalytic converter damage.

Thermostat stuck closed: If the thermostat is stuck closed it will restrict flow into the engine resulting in an overheating condition, resulting in potential catastrophic engine damage.

• Overheating engine
• Engine not reaching optimal running temperature
• Radiator fan not engaging

About Hella

Hella is a German based manufacturer of specialty lighting parts for automobiles and is an OEM (Original Equipment Manufacturer) for Audi, BMW, Mercedes, Mini, Subaru , Toyota, Volkswagen and more. Hella lighting solutions include headlights and fog-lights, complete headlight assemblies, and all the other internal bells and whistles that allow your vehicles lighting system to run impeccably every time you turn the ignition over. One of the most well-known automotive suppliers, Hella ranks highly among the top 50 producers of parts in the entire world and has expanded beyond lighting and into electronics for vehicle interiors. The company was technically founded in 1899, and initially was a producer of candles and lamps for horse drawn carriages. A lot has changed in over 100 years.