AISIN Engine Coolant Thermostat Kit THT-003 — OE-Matched Thermostat with Housing & Gasket for Toyota 4Runner/Tacoma/Tundra

This kit contains an AISIN-manufactured thermostat engineered to the original equipment specifications along with a matched housing and gasket for a dependable, leak-free installation. AISIN leverages decades of OEM experience to produce components that match factory form, fit, and function, ensuring the thermostat opens at the correct temperature and integrates cleanly into the vehicle's cooling system. Use this kit when replacing a worn or failing thermostat or whenever servicing the cooling system to maintain consistent engine temperature regulation.

How does this AISIN thermostat affect engine temperature control?

The thermostat regulates coolant flow between the engine and radiator, opening at the specified OE temperature to allow coolant circulation and closing to let the engine reach operating temperature faster. A correctly functioning thermostat helps maintain stable engine temperatures under varied driving conditions without altering factory calibration.

• OE-specified opening temperature for predictable thermal behavior
• Precision valve mechanism for consistent response to coolant heat
• Direct replacement design to match vehicle original performance

Will the housing and gasket included simplify installation?

Yes — the kit includes a matched housing and factory-style gasket to reduce installation time and the risk of leaks from mismatched parts. Having these components together eliminates the need to source additional parts and helps ensure a correct seal where the thermostat mounts.

• Thermostat housing shaped to OEM specifications for correct alignment
• New gasket reduces leak risk and prevents coolant seepage
• Single-kit purchase avoids trial-and-error part compatibility issues

Which vehicles is this AISIN THT-003 compatible with?

This thermostat kit fits select Toyota models and model years commonly equipped with the OEM-equivalent part; however, engine variants and production changes can affect compatibility. Confirm fitment with your vehicle’s year, model, and engine code before ordering to guarantee correct selection.

• Compatible models include Toyota 4Runner (2003–2022), FJ Cruiser (2007–2014), Tacoma (2005–2015), and Tundra (2005–2014)
• Fitment may vary by engine type — verify with the vehicle fit checker
• OE-equivalent design aims to match factory installation points and plumbing

How durable and reliable is an AISIN OE-matched thermostat?

AISIN manufactures thermostats to match original-engineering standards using quality materials and tested mechanisms. The company’s long history in OEM production supports consistent quality control and durability comparable to factory parts, reducing the chance of premature failure when installed and maintained properly.

• Built with high-grade materials for long service life
• Engineered to OEM tolerances for consistent operation over time
• Backed by AISIN’s reputation in original equipment manufacturing

Who is this for: This AISIN THT-003 thermostat kit is intended for Toyota owners, mechanics, and fleet technicians who need a direct-replacement thermostat kit to restore correct coolant flow and sealing. It’s a good choice when replacing an old or faulty thermostat, performing cooling-system maintenance, or preferring an OEM-matched component for reliability and correct operating temperature.