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Mercury Mountaineer Thermostat

7 items

Upgrade your vehicle's thermostat with A-Premium's high-quality options. Choose reliability and durability for a smoother ride.

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Engine Coolant Thermostat for 2002-2010 Mercury MountaineerEngine Coolant Thermostat for 2002-2010 Mercury Mountaineer
A-Premium®Part # APTHE005
Engine Coolant Thermostat for 2002-2010 Mercury Mountaineer
52 Reviews
CA$27.99
Enter ZIP codeFree standard shipping
2-year warranty
90 days free return
Fits Mercury Mountaineer: 2002 2003 2004 2005 2006 2007 2008 2009 2010
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Mercury Mountaineer
Item LocatedUnited States
Quantity1
MaterialMetal and Rubber
ConditionNew
item #1012N8VW
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Engine Coolant Thermostat for 2002-2010 Mercury Mountaineer
A-Premium®Part # APTHE038
Engine Coolant Thermostat for 2002-2010 Mercury Mountaineer
52 Reviews
CA$39.99
Enter ZIP codeFree standard shipping
2-year warranty
90 days free return
Fits Mercury Mountaineer: 2002 2003 2004 2005 2006 2007 2008 2009 2010
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Mercury Mountaineer
Item LocatedUnited States
Quantity1
MaterialMetal
ConditionNew
item #1012NPXE
Show less
Engine Coolant Thermostat for 2002-2010 Mercury Mountaineer
A-Premium®Part # APTHE040
Engine Coolant Thermostat for 2002-2010 Mercury Mountaineer
52 Reviews
CA$25.99
Enter ZIP codeFree standard shipping
2-year warranty
90 days free return
Fits Mercury Mountaineer: 2002 2003 2004 2005 2006 2007 2008 2009 2010
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Mercury Mountaineer
Item LocatedUnited States
Quantity1
ConditionNew
item #1014GSE4
Note
Start to Open Temperature: 91℃.
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Engine Coolant Thermostat for 2002-2010 Mercury Mountaineer
A-Premium®Part # APTHE003
Engine Coolant Thermostat for 2002-2010 Mercury Mountaineer
52 Reviews
CA$40.99
Enter ZIP codeFree standard shipping
2-year warranty
90 days free return
Fits Mercury Mountaineer: 2002 2003 2004 2005 2006 2007 2008 2009 2010
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Mercury Mountaineer
Item LocatedUnited States
Quantity1
MaterialMetal and Rubber
ConditionNew
item #1012N8EL
Show less
Engine Coolant Thermostat for 2002-2010 Mercury Mountaineer
A-Premium®Part # APTHE004
Engine Coolant Thermostat for 2002-2010 Mercury Mountaineer
52 Reviews
CA$40.99
Enter ZIP codeFree standard shipping
2-year warranty
90 days free return
Fits Mercury Mountaineer: 2002 2003 2004 2005 2006 2007 2008 2009 2010
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Mercury Mountaineer
Item LocatedUnited States
Quantity1
MaterialMetal and Rubber
ConditionNew
item #1012NE2W
Show less
Engine Coolant Thermostat Housing Assembly for 1998-2001 Mercury Mountaineer
A-Premium®Part # APTHA0023
Engine Coolant Thermostat Housing Assembly for 1998-2001 Mercury Mountaineer
52 Reviews
CA$53.99
Enter ZIP codeFree standard shipping
2-year warranty
90 days free return
Fits Mercury Mountaineer: 1998 1999 2000 2001
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Mercury Mountaineer
Item LocatedCanada
ColorBlack
ConditionNew
item #10047YCZ
Note
This part only fits V6 4.0L engine and for Ford Explorer 1997-2001, it only fit SOHC only
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Engine Coolant Thermostat for 1998-2010 Mercury Mountaineer
A-Premium®Part # APTHE094
Engine Coolant Thermostat for 1998-2010 Mercury Mountaineer
52 Reviews
CA$41.99
Enter ZIP codeFree standard shipping
2-year warranty
90 days free return
Fits Mercury Mountaineer: 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Mercury Mountaineer
Item LocatedUnited States
Quantity1
ConditionNew
item #10188N63
Note
Start to Open Temperature: 87℃.
Show less

What is an engine thermostat?

 While all engines can become too hot, if your thermostat isn't working correctly, your engine's well-being is at serious risk. The engine thermostat, often simply referred to as a thermostat, regulates the engine's operating temperature within an optimal range (typically around 195 to 220 degrees Fahrenheit).

How does a car thermostat work?

As a temperature-sensitive valve within the cooling system, a car thermostat responds to changes in coolant temperature. Understanding how it works by the following breakdown steps:

  • Closed position (cold start)

Initially closed to help the engine warm up quickly.

  • Heating up

The engine generates heat during operation.

  • Opening the thermostat

A temperature-sensitive element (usually wax) causes the thermostat to open gradually.

  • Coolant flow

When open, coolant flows from the engine to the radiator.

  • Maintaining optimal temperature

Adjusts coolant flow to maintain the ideal engine temperature.

  • Temperature regulation

Continuously adjusts to prevent overheating and ensure efficient operation.

Signs of a bad thermostat

  1. Overheating: The engine becomes excessively hot due to a stuck-closed thermostat.
  2. Low or fluctuating temperature: A thermostat stuck open results in a cooler engine, affecting fuel efficiency and heating.
  3. Temperature warning light: Illuminates to indicate engine overheating due to a faulty thermostat.
  4. Poor fuel efficiency: Stuck-open thermostat reduces fuel efficiency as the engine operates less efficiently at lower temperatures.
  5. Inadequate cabin heating: Insufficient cabin heating in cold weather with a thermostat that's stuck open.
  6. Coolant leaks: Gasket or sealing issues can lead to coolant leaks.
  7. Rapid temperature fluctuations: The gauge shows rapid swings between hot and cold.
  8. Engine running hot at idle: Higher engine temperature during idle or in traffic due to restricted coolant flow.
  9. Slow or inconsistent warm-up: Longer-than-normal warm-up times, even in moderate weather.
  10. Inconsistent heater operation: This affects the performance of the vehicle's heater, causing inconsistent or inadequate heating in cold weather.

Related Blogs

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Learn why coolant boils or bubbles after you turn the engine off, how heat soak affects the cooling system, and how to diagnose leaks, trapped air, cap, thermostat, fan, water pump, or head gasket problems.

Jul 29, 2026