Toyota Diesel OEM 1KZT 1KZTE 71°C Thermostat HiAce Hilux Surf Land Cruiser Prado 90916-03121

Product Overview

Genuine OEM Toyota Lower Temperature Thermostat compatible with 1993-2009 Toyota Hiace, Hilux, Surf, 4Runner, Prado, and Land Cruiser diesel models. This essential cooling system component opens at a lower temperature of 71°C (160°F) compared to the standard 82°C thermostat, providing improved cooling performance for high-demand applications. This OEM part is a perfect replacement for enhanced temperature management and reliable cooling system operation. 

OEM Part Number(s):

• 90916-03121 (primary for 71°C)
• 90916-03118 (standard temperature for 82°C)
• 90916-03119 (alternate for 76°C)

 

Key Features & Benefits

• Lower Opening Temperature: Opens at 71°C (160°F) vs standard 82°C for improved cooling performance
• Quality Assurance: Genuine OEM construction with precision wax element and durable housing
• Performance: Ideal for modified engines, heavy towing, high ambient temperatures, or aging cooling systems
• Complete Package: Includes a genuine Toyota thermostat gasket for proper installation 
• Value: Prevent overheating damage while maintaining OEM reliability standards

Technical Specifications

Part Type: Engine Coolant Thermostat Assembly
Opening Temperature: 71°C (160°F)
Engine Compatibility: 1KZT, 1KZ-TE, 1KD-FTV, 2KD-FTV, 1GD-FTV diesel engines
Material: Brass housing with precision wax element

Fitment

Year Range	Toyota Model	Engine Options
1993-2004	HiAce	1KZ-TE (all variants)
1993-2005	Hilux Surf / 4Runner	1KZT, 1KZ-TE (KZN130, KZN185, KZN215)
1999-2005	Hilux / 4Runner Truck	1KZ-TE (KZN165, KZN190, KZN205)
1993-1996	Land Cruiser	1KZT, 1KZ-TE (KZJ70, KZJ71, KZJ73, KZJ77, KZJ78)
1996-2009	Land Cruiser Prado	1KZT, 1KZ-TE, 1KD-FTV (KZJ90, KZJ95, KZJ120, KDJ120, KDJ125)
1995-2002	Granvia / Grand HiAce	1KZ-TE (KCH10, KCH16)
2000-2016	Hilux / Vigo	1KD-FTV, 2KD-FTV (later models)

Important: This thermostat is specifically designed for enhanced cooling performance. Verify engine code compatibility before purchase. Includes a genuine Toyota gasket for proper sealing at lower temperatures.

Installation & Maintenance

Installation Difficulty: Intermediate
Estimated Install Time: 1-2 hours
Tools Required: Socket set, drain pan, coolant funnel, torque wrench
Professional Installation: Recommended for proper coolant system bleeding and testing

Maintenance Tips:

• Drain the cooling system completely before installation
• Clean the thermostat housing thoroughly and inspect for damage
• Use genuine Toyota long-life coolant for optimal performance
• Properly bleed air from the cooling system after installation

 

Frequently Asked Questions

Q: What's included in the package?
A: Package includes the complete 71°C thermostat.

Q: Why choose a lower temperature thermostat?
A: The 71°C thermostat opens earlier than the standard 82°C version, providing better cooling for modified engines, heavy towing, high ambient temperatures, or aging cooling systems that run hotter than usual.

Related Toyota Parts You May Need

• Water Pump Assembly (16110-69357) - Essential for complete cooling system service
• Radiator Hoses - Inspect and replace during thermostat service
• Toyota Long Life Coolant - Genuine coolant for optimal performance
• Coolant Temperature Sensor - Monitor proper cooling system operation

 

Common Symptoms of Thermostat Failure

• The engine is running hotter than the normal temperature range
• Overheating during heavy loads or towing
• The engine takes too long to reach operating temperature
• Coolant is leaking from the thermostat housing 
• Poor heater performance in cold weather

 

Why Choose the Lower Temperature Thermostat

Enhanced Cooling Performance: The 71°C opening temperature provides superior cooling for demanding applications. This lower temperature thermostat helps moderate engine operating temperatures when higher-than-normal temperatures may be encountered due to aging cooling systems, high ambient temperatures, large vehicle loads, or modified engines.  

Toyota Land Cruiser and Hilux Surf owners report significant improvements in cooling performance, especially when towing or operating in hot climates. HiAce vans came from the factory with lower temperature thermostats, making this an ideal upgrade for other diesel applications.

Don't let overheating damage your valuable diesel engine. Upgrade to this genuine Toyota lower temperature thermostat for enhanced cooling protection and peace of mind during demanding driving conditions.