Calorstat THF1538.77 Engine Coolant Thermostat

Engine Cooling Control for Ford Applications

The Calorstat THF1538.77 engine coolant thermostat regulates coolant flow to help the engine reach and maintain the proper operating temperature. With a standard design and a 77 C / 171 F opening temperature, it is a direct-fit cooling system service part for a wide range of Ford, Lincoln, Mercury, Chevrolet, and Pontiac applications.

Use THF1538.77 when you need a thermostat that matches the specified sealing dimensions and opening point for temperature control in the cooling system. This part cross-references Motorad (e.g., 228-170JV, 2028-170) for the same application.

Key Features

• Calorstat THF1538.77 engine coolant thermostat
• Standard thermostat design for routine cooling system service
• Opening temperature: 77 C / 171 F
• Sealing flange outside diameter: 2.1
• Height between flanges: 1.38
• Fits a broad range of Ford F-150, F-250, F-350, Expedition, Explorer, Mustang, and E-Series applications

Detailed Description

The THF1538.77 is built for vehicles that require a thermostat with a 77 C / 171 F opening temperature to manage coolant circulation and engine warm-up. Its standard configuration and listed flange dimensions help support proper housing fitment during thermostat replacement. This makes it a practical service part for cooling system maintenance on Ford F-150, Ford F-250 Super Duty, Ford F-350 Super Duty, Ford Expedition, Ford Explorer, and related models.

Compatible With 1997-2014 Ford F-150, 1997-2009 Ford F-250, 1999-2022 Ford F-350 Super Duty, 1997-2014 Ford Expedition, 2002-2010 Ford Explorer, and additional listed Ford, Lincoln, Mercury, Chevrolet, and Pontiac vehicles. The Calorstat THF1538.77 is also referenced by part number THF1538.77 for catalog and lookup purposes.

What This Thermostat Helps Address

• Engine running too cool or taking too long to reach operating temperature
• Temperature fluctuations caused by a worn thermostat
• Cooling system service needs during thermostat housing repair
• Incorrect coolant flow control affecting heater performance
• Replacement of a thermostat with the specified 77 C / 171 F opening point

Installation Notes and Tips

Verify the thermostat opening temperature, sealing flange diameter, and height between flanges against the original part before installation. Inspect the thermostat housing, gasket surface, and coolant condition at the same time to reduce repeat service. Confirm vehicle-specific fitment for your exact year, make, and model, especially on Ford truck, van, and SUV applications.

Quality Assurance

Calorstat cooling system components are cataloged for thermostat and housing service applications, with fitment and dimensional data provided for accurate replacement selection. Confirm the part number THF1538.77 and the vehicle listing before installation.