A Guide to the Engine Coolant Thermostat for the 2020-2024 Lincoln Aviator
Understanding thermostat issues in your Aviator's 3.0L V6 engine and how to choose the right replacement part.
- A thermostat failing 'stuck open' is the most common issue, leading to a P0128 code and poor cabin heat.
- A 'stuck closed' thermostat is a critical failure that will cause overheating; shut off the engine immediately.
- There are no specific recalls or TSBs for thermostat failure on the 2020-2024 Aviator.
- For a stock Aviator, choose an OEM-equivalent brand like Gates or Motorad; avoid lower-temperature 'performance' thermostats.
Symptoms of a Failing Thermostat in a Lincoln Aviator
A thermostat can fail in two ways: stuck open or stuck closed. Each has its own distinct set of symptoms.
Stuck Closed: Overheating Risk
This is the more serious failure. If the thermostat is stuck closed, it traps coolant in the engine, preventing it from reaching the radiator to cool down. This will cause the engine to overheat quickly.
- Temperature gauge shoots up into the red zone.
- Warning lights for high engine temperature on the dashboard.
- Gurgling or boiling sounds from the engine bay.
- Coolant may leak or be forced out of the reservoir cap due to extreme pressure.
If you see these signs, pull over safely and shut off the engine immediately to prevent catastrophic engine damage.
Stuck Open: Poor Performance
A thermostat stuck open allows coolant to circulate constantly, even when the engine is cold. This prevents the engine from reaching its proper operating temperature.
- Engine takes a very long time to warm up.
- Temperature gauge stays on the low end and may even drop during highway cruising.
- Heater blows lukewarm or cold air, even when the engine has been running.
- Check Engine Light with code P0128 (Coolant Temperature Below Thermostat Regulating Temperature).
- A noticeable decrease in fuel economy over time.
Known Issues, Recalls, and TSBs
As of early 2026, there are no specific NHTSA recalls or Technical Service Bulletins (TSBs) for widespread failure of the engine coolant thermostat on the 2020-2024 Lincoln Aviator. While numerous recalls exist for other components like the backup camera and seats, the thermostat itself has not been identified as a common defect by the manufacturer. Any failure is typically due to normal wear and tear over time.
Choosing the Right Aftermarket Thermostat
When replacing the thermostat on your Aviator, you have a few options. The price difference between an OEM part from the dealer and an aftermarket part can be significant.
OEM-Equivalent Aftermarket Brands
- Gates & Motorad: These brands produce standard replacement thermostats designed to match the original factory specifications. In the aftermarket world, it's common for one manufacturer to produce parts that are then packaged and sold by other brands; you may find a Motorad-stamped thermostat inside a Gates box. For a daily driven vehicle, a standard replacement from a reputable brand like Gates or Motorad is a cost-effective choice that will restore original performance.
Performance Aftermarket Brands
- Mishimoto: Mishimoto specializes in performance cooling parts, including thermostats that open at a lower temperature than the factory unit. While this can be beneficial for heavily modified or racing engines, it is not recommended for a stock Lincoln Aviator. Using a lower-temperature thermostat can prevent the engine from reaching its proper operating temperature, leading to decreased fuel efficiency, incomplete combustion, and potentially triggering a P0128 check engine light code.
A Note on OEM vs. Aftermarket
The OEM thermostat assembly for the Aviator can be very expensive, sometimes costing several hundred dollars from a dealer. This is because it is often a complex component, possibly including the housing and electronic controls. Aftermarket parts offer a much more affordable alternative. While some mechanics prefer the build quality of OEM parts, a quality aftermarket unit from a known brand provides a reliable and budget-friendly repair for most owners.
Replacement Cost
The cost to replace the thermostat can vary greatly depending on whether you do the work yourself or hire a professional. The part itself is relatively inexpensive, but labor can be high due to the location of the thermostat on the 3.0L V6 engine.
| Item | Estimated Cost |
|---|---|
| New Aftermarket Thermostat Part | $20 - $70 |
| Shop Labor | $195 - $286 |
| Total Professional Replacement | $599 - $690 (including a higher-priced OEM part) |
Costs are estimates and can vary by location and repair shop. The total professional replacement cost often includes a dealer-sourced OEM part, which is significantly more expensive than aftermarket options.
Frequently Asked Questions
Can I drive my Aviator with a bad thermostat?
If the thermostat is stuck closed and the engine is overheating, NO. Stop driving immediately to avoid severe engine damage. If it's stuck open and the engine is running too cool, you can drive short distances to get to a repair shop, but it's not recommended for long-term use as it can affect fuel economy and emissions systems.
Why is the check engine light on for a thermostat problem?
The most common reason is error code P0128. This code is set by your Aviator's computer when it detects that the engine is not warming up to the correct temperature in the time expected. This is a classic symptom of a thermostat that is stuck open.
Is replacing the thermostat a DIY job?
For the 2020-2024 Lincoln Aviator, this is not recommended for beginners. The thermostat is located in a tight spot on the 3.0L V6 engine, and replacement requires draining the coolant, removing several components for access, and properly bleeding the system afterward. Given the complexity, most owners will want to leave this job to a professional mechanic.
Should I use a Mishimoto 'racing' thermostat?
No, not for a standard, daily-driven Aviator. These are designed to open at a lower temperature for track or high-performance use. In a stock vehicle, this can trick the engine's computer into thinking it's always cold, which can hurt performance and efficiency.
Technical Specifications
OEM Part Numbers: RT-1258
Fits 3.0L V6 Turbocharged Engine. Standard replacement thermostats for the Aviator are typically rated to open around 180°F-190°F. The OEM part is likely an electronically controlled unit integrated with its housing.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
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