How to replace a thermostat in a cooling system on Mercury Mountaineer?

Check the coolant level, drive belt tension, and temperature gauge before blaming the thermostat for cooling issues. If the engine warms up slowly or runs hot without a hot upper radiator hose, the thermostat may be stuck open or closed and need replacing. Don't drive without a thermostat as it affects emissions and fuel economy. To replace, disconnect the negative battery terminal, drain the cooling system, and remove the alternator harness bracket or engine trim cover. Find the thermostat housing by tracing the upper radiator hose to the engine, loosen the hose clamp, and remove the deteriorated hose if needed. Replace the thermostat housing cover if damaged. Remove the fasteners, detach the thermostat cover, remove the thermostat, clean off old gasket residue, fit a new gasket, and secure the thermostat housing cover, then refill the cooling system and start the engine. Let it reach normal temperature and check for leaks and proper functioning.

Genuine Mercury Mountaineer Thermostat

Engine Coolant Thermostat

Select Vehicle by Model
Select Vehicle by VIN

Select Vehicle by Model

Make

Model

Year

Select Vehicle by VIN

For the most accurate results, select vehicle by your VIN (Vehicle Identification Number).

6 Thermostats found

View related parts
Mercury Mountaineer Thermostat Assembly
Part Number: 7L3Z-8575-B
$21.78 MSRP: $30.91
You Save: $9.13 (30%)
ADD TO CART
Product Specifications
- Other Name: Thermostat Assy
- Replaced by: 7L3Z-8575-E
- Warranty: This genuine part is guaranteed by Ford's factory warranty.
Fits the following Vehicles:
- 2002-2010 Mercury Mountaineer | 8 Cyl 4.6L, 8 Cyl 4.6L Romeo SOHC EFI | 5-Speed Automatic Transmission 5R55S, 5-Speed Automatic Transmission 5R55W, 5-Speed Manual Transmission (M5R4), 6-Speed Automatic Transmission (6R80), 6-Speed Automatic Transmission 6R60, Four-Wheel Drive (Full Time) (Left Hand Drive), Four-Wheel Drive (Part Time) (Left Hand Drive), Four-Wheel Drive (Part Time) (Right Hand Drive), Left Hand Drive, Rear-Wheel Drive (Left Hand Drive)
View related parts
Mercury Mountaineer Thermostat Assembly
Part Number: 2L2Z-8575-AA
$19.38 MSRP: $30.91
You Save: $11.53 (38%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Thermostat Assy; Thermostat
- Replaces: 1L2Z-8575-AA
- Warranty: This genuine part is guaranteed by Ford's factory warranty.
Fits the following Vehicles:
- 2002-2010 Mercury Mountaineer | 6 Cyl 4.0L SOHC EFI | 5-Speed Automatic Transmission 5R55S, 5-Speed Automatic Transmission 5R55W, 5-Speed Manual Transmission (M5R4), 6-Speed Automatic Transmission (6R80), 6-Speed Automatic Transmission 6R60, Four-Wheel Drive (Full Time) (Left Hand Drive), Four-Wheel Drive (Part Time) (Left Hand Drive), Four-Wheel Drive (Part Time) (Right Hand Drive), Left Hand Drive, Rear-Wheel Drive (Left Hand Drive)
View related parts
Mercury Mountaineer Thermostat Assembly
Part Number: XL2Z-8575-AB
$7.09 MSRP: $11.31
You Save: $4.22 (38%)
Ships in 1 Business Day
ADD TO CART
Product Specifications
- Other Name: Thermostat Assy
- Manufacturer Note: #XL2E 8575-AB (same as XL2Z 8575-AA, except new and improved jiggle pin), FROM 8/9/99
- Replaced by: XR3Z-8575-BA
- Warranty: This genuine part is guaranteed by Ford's factory warranty.
Fits the following Vehicles:
- 1999-2001 Mercury Mountaineer | 8 Cyl 5.0L | 4AT 4R70W, 5AT 5R55E
View related parts
Mercury Mountaineer Thermostat Assembly
Part Number: F7TZ-8575-A
$32.03 MSRP: $51.09
You Save: $19.06 (38%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Thermostat Assy
- Manufacturer Note: Thermostat, SOHC
- Replaced by: YU3Z-8575-AA
- Warranty: This genuine part is guaranteed by Ford's factory warranty.
Fits the following Vehicles:
- 1998-2001 Mercury Mountaineer | 6 Cyl 4.0L | 4AT 4R70W, 5AT 5R55E
View related parts
Mercury Mountaineer Thermostat Assembly
Part Number: 1L2Z-8575-AA
$19.38 MSRP: $30.91
You Save: $11.53 (38%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Thermostat Assy
- Replaced by: 2L2Z-8575-AA
- Warranty: This genuine part is guaranteed by Ford's factory warranty.
Fits the following Vehicles:
- 2002 Mercury Mountaineer | 6 Cyl 4.0L SOHC EFI | 5-Speed Automatic Transmission 5R55S, 5-Speed Automatic Transmission 5R55W, 5-Speed Manual Transmission (M5R4), 6-Speed Automatic Transmission (6R80), 6-Speed Automatic Transmission 6R60, Four-Wheel Drive (Full Time) (Left Hand Drive), Four-Wheel Drive (Part Time) (Left Hand Drive), Four-Wheel Drive (Part Time) (Right Hand Drive), Left Hand Drive, Rear-Wheel Drive (Left Hand Drive)
View related parts
Mercury Mountaineer Thermostat Assembly
Part Number: AL2Z-8575-A
Product Specifications
- Other Name: Thermostat Assy
- Replaced by: AL2Z-8575-B
- Warranty: This genuine part is guaranteed by Ford's factory warranty.
Fits the following Vehicles:
- 2006-2010 Mercury Mountaineer | 6 Cyl 4.0L SOHC EFI | 5-Speed Automatic Transmission 5R55S, 5-Speed Automatic Transmission 5R55W, 5-Speed Manual Transmission (M5R4), 6-Speed Automatic Transmission (6R80), 6-Speed Automatic Transmission 6R60, Four-Wheel Drive (Full Time) (Left Hand Drive), Four-Wheel Drive (Part Time) (Left Hand Drive), Four-Wheel Drive (Part Time) (Right Hand Drive), Left Hand Drive, Rear-Wheel Drive (Left Hand Drive)

Mercury Mountaineer Thermostat Parts Questions & Experts Answers

Thermostat Assembly
1L2Z-8575-AA
Q: How to replace a thermostat in a cooling system on Mercury Mountaineer?
A: Check the coolant level, drive belt tension, and temperature gauge before blaming the thermostat for cooling issues. If the engine warms up slowly or runs hot without a hot upper radiator hose, the thermostat may be stuck open or closed and need replacing. Don't drive without a thermostat as it affects emissions and fuel economy. To replace, disconnect the negative battery terminal, drain the cooling system, and remove the alternator harness bracket or engine trim cover. Find the thermostat housing by tracing the upper radiator hose to the engine, loosen the hose clamp, and remove the deteriorated hose if needed. Replace the thermostat housing cover if damaged. Remove the fasteners, detach the thermostat cover, remove the thermostat, clean off old gasket residue, fit a new gasket, and secure the thermostat housing cover, then refill the cooling system and start the engine. Let it reach normal temperature and check for leaks and proper functioning.