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If you drive a Mercedes-Benz ML-Class, a properly functioning thermostat keeps engine temperature in the optimal range for efficiency and longevity. Choosing the right thermostat matters because a wrong or failing unit can cause overheating, poor cabin heat, or increased wear on engine components.This guide covers seven shortlisted thermostats selected for fitment compatibility and thermal performance. We evaluated each option for ease of installation, accuracy of temperature regulation, and build quality to help you find a replacement that restores proper cooling behavior. Read on for the criteria we used and what to look for when replacing your vehicle thermostat.
Looking for other parts? See all Mercedes-Benz ML-Class parts & accessories.
Top Picks at a Glance
| Best Reviewed A top-rated pick with lots of positive feedback | XYWZV Thermostat Housing Water Outlet for Mercedes CLA250/GLA250/CLA45/GLA45 2.0L |  |
| Most Popular A crowd favorite that many people choose with confidence | IRONTEK Thermostat Housing Assembly for Mercedes-Benz C250 / SLK250 |  |
| Best Quality Built to a higher standard if you want something more solid | Mercedes‑Benz Engine Coolant Thermostat Housing (276 200 05 15) |  |
| Best Budget The cheapest option that still gets the job done reliably | Gates 33930 Integrated Housing Engine Coolant Thermostat |  |
| Most Sold A high-volume bestseller chosen again and again | C-Tzu Aluminum Thermostat Housing Assembly with Sensor for Mercedes-Benz |  |
| Best Value for Money The sweet spot between price and what you get | Mercedes‑Benz Engine Coolant Thermostat Kit (112 203 02 75) |  |
| Best Overall The best all-around choice for most situations | TRQ Thermostat with Housing Assembly for Mercedes-Benz |  |
1. XYWZV Thermostat Housing Water Outlet for Mercedes CLA250/GLA250/CLA45/GLA45 2.0L
| Replaces part numbers | 2702000615, 2702002200, 2702000415 |
|---|---|
| Fitment (listed) | Mercedes CLA250, GLA250, CLA45 AMG, GLA45 AMG 2.0L |
| Manufacturer | XYWZV |
This thermostat housing water outlet is a direct-fit replacement intended to restore proper coolant routing and temperature control on compatible Mercedes 2.0L models. It installs in place of the factory housing to route coolant between the engine and radiator and houses the thermostat that helps keep operating temperature stable. The listing emphasizes durability testing including pressure and temperature checks, and multiple customer reports note an OEM-like fit and straightforward installation. In practice this means fewer surprises during installation and a good chance of sealing correctly when gaskets and mounting surfaces are prepared. Limitations include dependence on correct part selection for your specific engine and the fact that long-term durability beyond initial tests is based on limited user history. Buyers should also plan to replace associated seals and inspect surrounding components while the cooling system is open to avoid repeat work.
Best for: Reliability-focused buyers who prioritize getting a factory-quality replacement that reduces downtime and restores correct coolant control on their Mercedes, aiming to keep the cooling system dependable.
Less Ideal for: Owners who prefer factory-brand parts from the vehicle dealer or those seeking a covered long-term warranty should consider alternate sources.
- Direct-fit design that aligns with factory mounting points for straightforward installation
- Manufacturer reports pressure and temperature testing for improved initial reliability
- Replaces multiple Mercedes part numbers reducing risk of ordering the wrong unit
- Customers report OEM-like appearance and successful fit on compatible vehicles
- Limited long-term durability data compared with established OEM suppliers
- Product documentation does not include torque or installation details specific to Mercedes models
Verdict A well-tested, direct-replacement thermostat housing that gives reliability-minded Mercedes owners an affordable OEM-style fix, with limited long-term track record.
2. IRONTEK Thermostat Housing Assembly for Mercedes-Benz C250 / SLK250
| Fitment | 2012–2015 Mercedes-Benz C250, SLK250 |
|---|---|
| Manufacturer | IRONTEK |
| Manufacturer Part Number | IRKTMH8024 |
| Customer Reviews | 4.4 out of 5 stars |
This IRONTEK thermostat housing assembly replaces the factory housing, thermostat and coolant temperature sensor mounting in one unit for compatible 2012–2015 Mercedes-Benz C250 and SLK250 vehicles. It is intended for a straightforward swap during routine cooling-system repairs: remove the old housing, transfer hoses and sensor, and install the assembly with its gasket to restore coolant routing and correct temperature readings. Buyers mention easy fitment and quick installation, and the integrated design can cut labor time versus replacing separate components. The housing is marketed as a direct replacement and is backed by multiyear after-sales support. Limitations to consider are build quality variability reported by some users and occasional fitment issues with the supplied O-ring or electrical connector that may require minor modification or a replacement seal. This part is best used as a practical, convenience-focused alternative to dealer parts when you need a fast, complete housing swap for the specified Mercedes models.
Best for: Convenience-driven buyers who prioritize a quick, all-in-one replacement to get a 2012–2015 Mercedes-Benz C250 or SLK250 back on the road with minimal parts-sourcing and shop time.
Less Ideal for: Owners seeking factory-brand components or who prefer to replace individual cooling-system parts separately should consider dealer or OEM options instead.
- Designed as a one-piece replacement combining housing and thermostat for faster installation
- Sold to fit specified 2012–2015 Mercedes-Benz C250 and SLK250 models for direct compatibility
- Includes provision for the coolant temperature sensor to restore OEM sensor mounting and routing
- Manufacturer offers multi-year after-sales service for replacement support
- Some customers report the supplied O-ring or gasket arrangement is incorrect and may need swapping
- Electrical connector on the housing can be fragile and may break during installation in a few cases
Verdict A convenient, integrated replacement housing for specified 2012–2015 Mercedes-Benz C250 and SLK250 models that speeds repairs but may require checking the supplied seal and connector during installation.
3. Mercedes‑Benz Engine Coolant Thermostat Housing (276 200 05 15)
| Manufacturer | Mercedes-Benz |
|---|---|
| Item model number | 276-200-05-15 |
| Manufacturer Part Number | 276 200 05 15 |
| OEM Part Number | 276 200 05 15 |
This is the genuine Mercedes‑Benz thermostat housing intended to replace the factory unit on compatible Mercedes V6 applications. It installs in place of the original housing and routes coolant through the thermostat assembly; typical use is direct replacement during cooling system repairs or when a failing housing/thermostat needs service. Notable features include stamped Mercedes part marking and OEM fitment, which helps ensure correct alignment and sealing with factory gaskets and hoses. The housing’s factory-quality construction reduces the risk of leaks and fitment issues that can accompany aftermarket castings, and multiple user reports note straightforward installation and proper function. Important limitations are that this listing supplies only the housing assembly referenced and not additional hoses, sensors, or extra mounting hardware, and buyers should verify vehicle model and year compatibility before ordering. Expect OEM-level reliability but plan for standard installation steps and possibly replacing associated seals and the thermostat when servicing the cooling system.
Best for: Performance-oriented buyers who prioritize factory-quality parts and reliable cooling under demanding driving, especially those who prefer maintaining factory specifications for optimal engine performance.
Less Ideal for: Buyers seeking the lowest possible cost repair or those who want a full parts kit in one purchase should consider aftermarket options or bundled kits instead.
- Genuine Mercedes‑Benz factory replacement for correct fit and finish
- Stamped part number aids identification and confirms authenticity
- Factory-quality casting reduces leak risk and improves long-term reliability
- Direct replacement design simplifies installation for technicians familiar with Mercedes cooling systems
- Only the housing is included so related items like sensors, thermostat, or gaskets may need separate purchase
- Higher cost than generic aftermarket housings
Verdict Choose this genuine Mercedes housing if you want factory-fit reliability for a performance-focused Mercedes cooling system repair.
4. Gates 33930 Integrated Housing Engine Coolant Thermostat
| Brand Name | Gates |
|---|---|
| Included Components | Engine Coolant Thermostat |
| Model Number | 33930 |
| Mounting Type | Engine Block Mount |
This Gates 33930 combines the thermostat and water outlet into a single integrated housing to simplify replacement on compatible Mercedes-Benz engines. It mounts directly to the engine block and fixes thermostat orientation when the housing is bolted in, which cuts installation time and reduces alignment headaches. The product is designed for hardwired, wired connectivity descriptions listed in its specs do not affect fitment; in practical use you treat it as a direct mechanical replacement. Buyers report straightforward installation with two bolts and easy hose access, and the integrated housing helps prevent leaks when torqued evenly. One limitation is occasional missing gasket reports, so confirm the listing includes the seal you need or have a replacement gasket on hand. Also the listing includes industrial-style spec entries that do not change fitment or function on Mercedes cooling systems. For a budget replacement that matches factory fit and keeps cooling performance normal, this part covers the basics without extras like upgraded materials or extended-service features.
Best for: Budget-conscious Mercedes-Benz owners who prioritize an affordable, factory-style replacement that is simple to install and restores normal cooling system function.
Less Ideal for: Owners seeking performance upgrades, extended-life materials, or professional shops wanting parts with bundled seals and extras should consider higher-end or OEM-specified alternatives.
- Integrated thermostat and water outlet simplifies installation and ensures correct orientation during fitment.
- Direct bolt-on design mounts to the engine block for a factory-quality replacement.
- Multiple customer reports of easy installation and good fit on Mercedes vehicles.
- Compact assembly with few fasteners makes DIY replacement quicker than separate components.
- Some customers reported the gasket was missing from the package so you may need to provide your own seal.
- No advertised performance upgrades over factory-spec thermostats.
Verdict A cost-conscious, direct-fit thermostat assembly for Mercedes-Benz that makes replacement simple but does not add performance enhancements.
5. C-Tzu Aluminum Thermostat Housing Assembly with Sensor for Mercedes-Benz
| Manufacturer | C-Tzu |
|---|---|
| Model | 047-062 |
| Manufacturer Part Number | 2722000115 |
| Thermostat Opening Temperature | 212 Deg. F / 100 °C |
This C-Tzu aluminum thermostat housing assembly replaces the factory housing and includes the temperature sensor required for the cooling system on compatible Mercedes-Benz V6 applications. It installs in place of the original housing to restore proper coolant flow and thermostat operation, helping the engine reach and hold operating temperature. The housing is cast from aluminum, which provides corrosion resistance compared with many plastic housings, and the unit is pre-fitted with the sensor port to simplify installation. Real-world benefits include correcting temperature-related fault codes and reducing coolant leaks around the thermostat area when the factory housing has failed. Some buyers report fit and function equal to factory-quality parts, while a minority experienced issues with temperature fluctuation or leaks over time, so careful installation and proper sealing are important. If you need a direct replacement for an ML350 V6 or other listed Mercedes models, this is a practical, budget-conscious option that can return the cooling system to normal operation.
Best for: A risk-averse mainstream buyer looking for a cost-effective, function-focused replacement to return a Mercedes ML-Class cooling system to reliable service without aftermarket performance modifications.
Less Ideal for: Drivers who prioritize long-term factory-backed durability or who prefer dealer-sourced parts should consider factory-quality replacements instead.
- Aluminum construction offers better corrosion resistance than many plastic housings
- Ships with sensor provision so you do not need to transfer the factory sensor separately
- Direct-replacement fit for many Mercedes V6 applications, simplifying swap-out
- Helps resolve coolant temperature faults and restore proper thermostat regulation
- Some users reported temperature regulation inconsistencies or leaks after months of use
- Not all units fit every submodel despite broad fitment listing, so verification before installation is necessary
Verdict A budget-friendly aluminum replacement that restores thermostat function for compatible Mercedes V6 models but check fit and sealing carefully before installation.
6. Mercedes‑Benz Engine Coolant Thermostat Kit (112 203 02 75)
| Manufacturer Part Number | 112 203 02 75 |
|---|---|
| Brand | Mercedes Benz |
| Includes | Thermostat and housing |
| Compatible With | Selected Mercedes‑Benz models (see fitment) |
This is a factory‑quality thermostat housing kit that replaces the original Mercedes‑Benz part 112 203 02 75. It installs in place of the existing housing and includes the thermostat, making it a direct factory replacement for affected Mercedes V6 and V8 engines. In everyday use the kit returns correct warm‑up and operating temperature, which fixes common symptoms like poor cabin heat, P0128 codes, and slow thermostat response. Reviewers report straightforward installs that usually require minimal disassembly and standard hand tools. Because it is a genuine Mercedes part, fitment and sealing are precise and the built‑in rubber gasket reduces fuss during removal and reinstallation. The main limitation is that this is a model‑specific OEM part, so you must confirm exact fitment for your ML‑Class engine variant before buying, and OEM replacement parts can cost more than aftermarket alternatives despite their fit and reliability benefits.
Best for: Practical optimizers who prioritize a reliable, factory‑quality repair that keeps their ML‑Class running to factory standards without experimenting with aftermarket options.
Less Ideal for: Buyers who need a universal or multi‑vehicle aftermarket thermostat solution or those strictly seeking the lowest upfront cost regardless of factory fitment.
- Genuine Mercedes‑Benz factory replacement for exact fit and compatibility
- Includes thermostat and integrated gasket to simplify installation
- Consistent performance fixing common overheating or under‑heating symptoms
- Model‑specific part so it only fits the listed Mercedes engines and years
- OEM cost is typically higher than aftermarket alternatives
Verdict A factory Mercedes‑Benz thermostat housing kit that restores correct engine temperature control for ML‑Class owners who want a reliable, OEM replacement.
7. TRQ Thermostat with Housing Assembly for Mercedes-Benz
| Material | Aluminum |
|---|---|
| Gasket Or Seal Included | Yes |
| Opening Temperature | 100 Deg. C / 212 Deg. F |
| Reference Numbers | 2722000015, 2722000115, 902-5912, HVA00838 |
This TRQ thermostat with housing is a one-piece replacement intended to restore engine cooling control on compatible Mercedes‑Benz models in the ML-Class family. It combines the thermostat and metal housing into a preassembled unit so installers can swap the entire assembly without mating separate parts. The aluminum housing and included gasket reduce the chance of warping and the part opens at about 100 C (212 F), matching common factory opening temperatures. Buyers will use this as a direct replacement during routine cooling system repairs or when a failing plastic housing needs upgrading to a more durable metal assembly. Practical benefits include simpler installation thanks to the assembled design and a more robust exterior than many plastic originals. Some customers report occasional quality control issues such as damaged O-rings or used-looking returns, so inspect the seal and machining before installation and keep coolant recovery in mind during replacement. Fitment must be confirmed for the exact Mercedes model and year before purchase.
Best for: A balanced all-round buyer who wants a durable, factory-style replacement that simplifies a thermostat housing repair and values reliable cooling performance over lowest-cost options.
Less Ideal for: Do not choose this if you need a universal or experimental solution; technicians needing full OEM-branded parts or extended warranties may prefer dealer-sourced components.
- Preassembled thermostat and housing simplifies installation and saves assembly time.
- Aluminum housing offers greater resistance to warping compared with common plastic housings.
- Includes gasket for a complete replacement that reduces parts sourcing during repair.
- Opening temperature matches typical factory spec at 100 C (212 F).
- Some buyers reported units with damaged O-rings or signs of prior use indicating occasional quality control lapses.
- Fitment errors are possible if vehicle application is not double-checked before ordering.
Verdict A practical, metal direct-fit replacement that makes ML‑Class thermostat housing swaps easier, but inspect seals on arrival due to occasional QC issues.
Choosing the Right Mercedes-Benz ML-Class Thermostat: Key Factors to Consider
Fitment Compatibility
Correct fitment is the first priority because the thermostat must mate precisely with the ML-Class coolant passages and housing to prevent leaks and ensure proper flow. A unit with incorrect dimensions or mismatched mounting holes can cause coolant loss or create air pockets that affect circulation. Fitment also affects alignment with sensor ports when present, which is important for accurate temperature reading.
When fitment is right you avoid extra work such as modifying housings or adapting seals. Confirming bolt pattern, flange shape, and overall depth helps ensure the thermostat seats correctly. Fitment accuracy reduces the risk of installation errors and subsequent coolant system issues.
Opening Temperature and Tolerance
The thermostat's opening temperature determines at what engine temperature coolant begins to circulate through the radiator. Choosing a thermostat with the specified opening point for the ML-Class engine helps the vehicle reach and maintain ideal operating temperature for emissions, efficiency, and heater performance. Equally important is the tolerance: how consistently the valve opens at the target temperature.
Wide variances or poor tolerance can lead to overheating or an engine that runs too cool. Look for units with documented opening temperatures and tight tolerances to match factory expectations. Reliable thermal response helps prevent temperature-related drivability issues.
Material Quality and Corrosion Resistance
Thermostat housings, valve components, and springs are exposed to coolant chemistry and varying temperatures, so durable materials matter. Corrosion-resistant metals and quality seals extend service life and reduce the chance of premature failure. Inferior materials can lead to leaks, sticking valves, or fractured housings under thermal stress.
Choosing components made from robust alloys and high-grade elastomers helps ensure long-term reliability. Consider materials that resist galvanic corrosion and hold up to the coolant type used in Mercedes-Benz vehicles to minimize maintenance and downtime.
Seal and Gasket Integrity
A proper seal between the thermostat and housing prevents coolant leakage and maintains system pressure. Gaskets and O-rings must resist heat, pressure, and coolant additives without hardening or shrinking. A poor seal can cause external leaks or allow air into the system, which undermines heater performance and can lead to overheating.
Inspect the quality and thickness of included gaskets, and whether a replacement requires a separate housing seal. Designs that integrate a durable sealing surface simplify installation and reduce the need for additional sealants or modifications.
Ease of Installation
Installation complexity affects how quickly you can return the vehicle to service and whether the job is feasible as a DIY task. Thermostats that align with factory mounting points, include clear instructions, and do not require specialized tools reduce labor time. Units that necessitate removal of ancillary parts or complex bleeding procedures increase the chance of mistakes.
Consider whether the thermostat design allows for straightforward gasket seating and whether the replacement keeps the cooling system layout intact. Simpler installations lower labor costs and reduce the likelihood of leaks or installation-related faults.
Thermal Performance and Valve Action
Beyond opening temperature, how smoothly and reliably the valve moves affects cooling system behavior. A valve that opens progressively and returns reliably when cooling is needed helps stabilize engine temperature and prevents oscillation between hot and cold states. Sticking or sluggish valves can cause symptoms ranging from overheating to poor cabin heating.
Reliable valve action also contributes to predictable warm-up times and steady coolant flow under varying loads. Assessments of thermal performance should consider both the mechanical action and the repeatability of opening and closing across many cycles.
FAQ
What are common signs of a failing thermostat in an ML-Class?
Common signs often include the engine running hotter than normal, inconsistent cabin heater output, or unusually long warm-up times. You may also notice temperature gauge fluctuations or coolant leaking near the thermostat housing. These symptoms usually indicate the thermostat is sticking closed, open, or that a seal has failed.
How do I test whether the thermostat is stuck open or closed?
You can observe engine warm-up behavior and gauge response; an engine that stays cool may indicate a thermostat stuck open, while rapid overheating suggests it is stuck closed. A more definitive test involves removing the thermostat and placing it in hot water to see at what temperature the valve opens, using a thermometer to compare against the specified opening point.
Should I replace the thermostat housing or reuse the old one?
If the housing shows visible corrosion, cracks, or damaged mounting surfaces, replacing it is advisable because a compromised housing can cause leaks or poor seal seating. If the housing is in good condition and sealing surfaces are intact, reusing it is often acceptable provided you replace gaskets or O-rings as recommended.
How important is matching the thermostat part number fitment for Mercedes-Benz ML-Class?
Matching the correct part number or verified fitment information is important to ensure proper mating with the ML-Class cooling passages and sensors. Using a unit with verified compatibility reduces the risk of leaks, misaligned sensors, or incorrect thermal behavior. Always confirm fitment details against your vehicle's model year and engine variant.
What routine maintenance helps prevent thermostat-related failures?
Regular coolant service and using the correct coolant type for Mercedes-Benz vehicles helps minimize corrosion and scale that can impair thermostat operation. Periodic inspection of hoses, clamps, and the thermostat housing for leaks can catch issues early. Maintaining a clean cooling system reduces stress on thermostat components and extends service life.
Can a thermostat cause overheating even if the radiator and water pump are fine?
Yes, a malfunctioning thermostat can restrict coolant flow or fail to open at the correct temperature, causing overheating despite a functional radiator and water pump. Because the thermostat regulates coolant flow to the radiator, its failure can be the primary cause of overheating symptoms.
How We Chose the Best Mercedes-Benz ML-Class Thermostat
To compile this list we focused on items that offer reliable fitment with Mercedes-Benz ML-Class engines and demonstrate consistent temperature control under typical driving conditions. Primary evaluation criteria included fitment accuracy to factory mounting and coolant passages, thermostat opening temperature tolerance and consistency, build materials and corrosion resistance, and compatibility with OEM cooling system components such as housings and seals.We also considered installation characteristics like whether common hand tools suffice, clarity of instructions, and whether the design minimizes the need to disturb related components. Durability factors such as valve material, spring design, and resistance to scale were part of the assessment. Units that required extensive modification, had unclear fitment information, or lacked verifiable temperature tolerance data were excluded. The result is a set of options that prioritize correct fit, predictable thermal response, and straightforward replacement for ML-Class owners.
Our full evaluation process is outlined in our review methodology.
Conclusion
When replacing a Mercedes-Benz ML-Class thermostat, prioritize correct fitment, verified opening temperature, and durable materials. Those factors have the biggest impact on sealing, thermal regulation, and long-term reliability.Balance ease of installation with the expected thermal performance and seal integrity. Addressing these core criteria will help you restore predictable engine temperature control and reduce the chance of recurring coolant system problems.
Explore More:
- Check out all Mercedes-Benz ML-Class parts & accessories
- Explore Thermostats Maintenance & Repair Guides
- Explore Cooling System
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