Gates 33738S Engine Coolant Thermostat

Gates Premium Thermostat for Nissan and Infiniti

The Gates Premium Thermostat 33738S is a direct-fit engine coolant thermostat built for temperature control in a wide range of Nissan and INFINITI applications. It uses heavy-gauge stainless steel construction with copper components for added corrosion resistance and stable operation under normal driving conditions.

Gates Premium Thermostat line parts are built for drivers who want OE-style cooling system performance with upgraded internal materials and spring design. This thermostat is specified at 180 degrees and is used across many Nissan Frontier, Xterra, Pathfinder, Quest, 300ZX, Maxima, and related applications.

Key Features

• Part number 33738S
• Premium thermostat design for engine coolant temperature regulation
• Stainless steel and copper construction
• Heavy-gauge metal body for improved corrosion resistance
• Upgraded spring for more stable temperature control
• Reverse poppet design
• 180 degree start-to-open temperature
• Jiggle pin weep hole included
• No gasket required; use silicone where specified in fitment notes

Detailed Description

This Gates thermostat is engineered for cooling systems that need consistent coolant flow control during warm-up and normal operation. The reverse poppet design and upgraded spring help maintain stable opening behavior, while the stainless steel construction supports long-term resistance to corrosion inside the cooling circuit. The 33738S is listed for 1984-2004 Nissan and INFINITI applications, including Nissan Frontier, Xterra, Quest, Pathfinder, 300ZX, Maxima, D21, Pickup, 200SX, and INFINITI QX4, J30, and M30.

This part cross-references Bosch 62398 for the same application.

What It Helps Address

• Engine running too cool or too warm due to thermostat wear
• Delayed warm-up after cold starts
• Temperature fluctuation during normal driving
• Corrosion-related thermostat housing concerns
• Cooling system service on Nissan and INFINITI vehicles

Installation Notes and Tips

• Fits 1999-2004 Nissan Frontier, N/A
• Fits 2002-2004 Nissan Xterra, N/A
• Fits 1996-2000 Nissan Pathfinder, N/A
• Fits 1997-2000 INFINITI QX4, N/A
• Fits 1985-1994 Nissan Maxima, N/A
• Follow the fitment notes for 180 degree or alternate temperature applications.
• Use silicone where the application notes specify that a gasket is not required.
• Verify the thermostat orientation and cooling system condition before reassembly.
• Bleed air from the cooling system after installation to help prevent hot spots.

Quality Assurance

Gates Premium Thermostat parts are built with stainless steel construction and an upgraded spring to support stable coolant temperature control under normal operating conditions. The 33738S is a premium replacement choice for Nissan Frontier, Xterra, Pathfinder, Quest, and related applications where OE-style temperature regulation is required.