Genuine OEM 2742003100 - Engine Coolant Thermostat Kit

Product Overview

This Genuine OEM 2742003100 engine coolant thermostat kit is engineered to factory specifications for Mercedes-Benz C-Class and GLC-Class plug-in hybrid models. It fits the W205 C350e (2016–2018) and X254 GLC350e 4MATIC (2018–2020) vehicles equipped with the 2.0 L4 PHEV powertrain. The thermostat regulates coolant temperature to maintain optimal engine efficiency and protect the hybrid electric system from thermal stress. Genuine OEM parts carry the same warranty and durability standards as factory components, ensuring reliable long-term performance in your Mercedes-Benz.

Symptoms of a Failing Thermostat

• Engine running hotter than normal; temperature gauge creeping into the red zone
• Coolant leaks around the thermostat housing or connections
• Inconsistent cabin heat or no heat at idle
• Check Engine light or coolant temperature warning messages on the dashboard
• Excessive fan noise as the cooling system works harder to regulate temperature
• Rough idle or hesitation when the engine is cold

Cross Reference Numbers

This Genuine OEM 2742003100 thermostat kit is equivalent to or replaces the following part numbers: 2742000115, 274200310, 2742003100.

Vehicle Compatibility

This thermostat kit fits the popular models below. For Fitment Confidence, please use the vehicle selector tool above to verify exact compatibility for your vehicle.

• Mercedes-Benz C350e 2.0 L4 PHEV (W205): 2016–2018
• Mercedes-Benz GLC350e 4MATIC 2.0 L4 PHEV (X254): 2018–2020

This may also fit other applications. Please use the vehicle selector tool to verify fitment.

Often Replaced Together

For a complete cooling system service, many owners replace the following at the same time:

• Engine coolant (flush and fill with OEM-approved specification)
• Coolant hoses and clamps
• Water pump (if showing age or mileage)
• Radiator cap and pressure relief valve

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Frequently Asked Questions

How do I know if my Mercedes-Benz W205 C350e or X254 GLC350e needs a new thermostat?

The most common sign is abnormal engine temperature readings. If your temperature gauge climbs higher than usual during normal driving, or if the fan runs constantly, the thermostat may be stuck open. Conversely, if the engine takes much longer to warm up on cold mornings, the thermostat may be stuck closed. Coolant leaks around the thermostat housing are another clear indicator. Consult your instrument cluster for any coolant temperature warnings or check codes.

Is this a complete kit or just the thermostat itself?

This is a complete thermostat kit from Genuine OEM, meaning it includes all necessary components and gaskets for a proper installation. Kits are engineered to work together and eliminate guesswork; you will not need to source additional seals or adapters separately.

What tools and skills do I need to replace this thermostat?

Thermostat replacement typically requires basic hand tools (socket set, screwdrivers, pliers), a drain pan for coolant, and a torque wrench to properly secure the thermostat housing. You will also need to drain and refill the cooling system. The job is moderately involved; if you are not comfortable working with coolant systems or do not have the necessary tools, a professional technician is recommended. Always consult your service manual for exact torque specifications and procedures.

Do I need to flush the entire cooling system when replacing the thermostat?

While not always mandatory, flushing the cooling system is strongly recommended when replacing the thermostat, especially if the system has not been serviced recently. Old coolant can contain sediment and contaminants that reduce heat transfer and may clog the new thermostat. A fresh coolant fill ensures maximum efficiency and protects your PHEV's hybrid electric components from thermal stress.

What coolant should I use for my Mercedes-Benz C350e or GLC350e?

Always use coolant that meets Mercedes-Benz OEM specifications. Your owner's manual or service documentation will specify the exact grade and type required. Using the wrong coolant can affect cooling performance and may void your warranty. If in doubt, consult your dealership or service advisor for the correct specification.

Can a stuck thermostat damage other cooling system components?

Yes. A thermostat stuck in the closed position forces the engine to overheat, which can damage the water pump, radiator, hoses, and even the engine itself over time. A stuck-open thermostat prevents the engine from reaching proper operating temperature, reducing efficiency and increasing emissions. Prompt replacement protects the entire cooling system and the hybrid powertrain.

Order Genuine OEM 2742003100 today to restore proper coolant temperature regulation in your Mercedes-Benz. In-stock orders ship same or next business day from our U.S. warehouse, and our fitment team is one call away if you need help confirming the right part for your C350e or GLC350e.

Note: All information on this page and in the FAQ is for general reference only. Verify fitment and consult a professional as needed. eEuroparts.com is not responsible for incorrect part selection or installation.