Calorstat TH5971.88 Engine Coolant Thermostat

Engine Coolant Thermostat for Select Mazda, Isuzu, Geo, Nissan, and Subaru

Calorstat TH5971.88 is a standard engine coolant thermostat built for precise coolant flow control and stable operating temperature. It features an off-set valve seat, a 2.12 in. sealing flange outside diameter, and a 0.96 in. height between flanges for applications that call for this OE-style configuration.

With a 190.0°F start-to-open temperature, this thermostat is specified for vehicles such as the Mazda B3000, Isuzu Pickup, and Isuzu Amigo, along with other listed applications. The TH5971.88 part number is also referenced in multiple aftermarket catalogs for the same application.

• Standard engine coolant thermostat for temperature regulation
• Off-set valve seat design for application-specific fitment
• 190.0°F start-to-open temperature
• 2.12 in. sealing flange outside diameter
• 0.96 in. height between flanges
• Gasket or seal not included

Detailed Product Overview

Calorstat TH5971.88 is an engine coolant thermostat used to manage coolant circulation so the engine reaches and maintains its operating temperature. The thermostat opens at 190.0°F, helping support consistent warm-up and temperature control in vehicles that require this specification. Its off-set valve seat and standard design make it a direct-match service part for a range of import and compact truck applications, including Mazda B3000, Isuzu Pickup, and Isuzu Amigo fitments.

This part number, TH5971.88, cross-references Four Seasons 33479 for the same application.

What This Thermostat Helps Address

• Engine running too cool or taking too long to warm up
• Temperature fluctuation caused by a worn thermostat
• Coolant flow issues related to a thermostat stuck open
• Overheating concerns tied to restricted thermostat operation
• Service replacement for OE-style cooling system maintenance

Installation Notes and Tips

Verify the thermostat housing and sealing surface before installation. Because a gasket or seal is not included, use the correct separate seal for the application. Confirm the 190.0°F opening specification, flange dimensions, and off-set valve seat design against the original part before installation on a Mazda B3000, Isuzu Pickup, Isuzu Amigo, or other listed vehicle.

• Fits 2008 Mazda B3000, N/A
• Fits 1993-1995 Isuzu Pickup, N/A
• Fits 1988-1991 Isuzu Pickup, N/A
• Fits 1993-1994 Isuzu Amigo, N/A
• Fits 1989-1991 Isuzu Amigo, N/A
• Fits 1992-1993 Geo Storm, N/A
• Fits 1992 Isuzu Impulse, N/A
• Fits 1985-1988 Isuzu Impulse, N/A
• Fits 1985-1989 Isuzu I-Mark, N/A
• Fits 1988 Nissan Pulsar NX, N/A
• Fits 1987 Subaru Standard, N/A
• Fits 1984-1985 Mazda 626, N/A
• Fits 1983 Nissan 280ZX, N/A

Quality Assurance

Calorstat TH5971.88 is built to match the listed cooling-system specifications and application references for select Mazda, Isuzu, Geo, Nissan, and Subaru vehicles. The part number TH5971.88 is also listed alongside multiple aftermarket interchange references for service matching.