Gates 33737S Engine Coolant Thermostat

Gates Premium Thermostat for Nissan and Infiniti

The Gates Premium Thermostat 33737S is an engine coolant thermostat built for temperature control in a range of Nissan, INFINITI, and Mercury applications. It uses stainless steel and copper construction with a reverse poppet design and a jiggle pin weep hole for stable coolant flow and air bleeding during service.

Gates Premium Thermostat line components are built with upgraded spring tension and corrosion-resistant materials to support consistent opening temperatures under normal operating conditions. This thermostat is a 170-degree unit and is listed for OE and alternate temperature applications across multiple Frontier, Xterra, Pathfinder, Quest, 300ZX, Maxima, and related models.

Key Features

• Part number 33737S
• Premium thermostat design for engine coolant temperature regulation
• Stainless steel and copper construction for corrosion resistance
• Reverse poppet design
• 170-degree start-to-open temperature
• Jiggle pin weep hole included for air purge during cooling system service
• No gasket required on listed applications; use silicone where specified in fitment notes

Detailed Description

Gates 33737S is an engine coolant thermostat for drivers servicing cooling systems on Nissan Frontier, Nissan Xterra, Nissan Pathfinder, Nissan Quest, Nissan 300ZX, Nissan Maxima, INFINITI QX4, INFINITI J30, INFINITI M30, and Mercury Villager applications. The heavy-gauge stainless steel body and copper components are selected for improved corrosion resistance, while the upgraded spring helps maintain temperature stability during normal operation. This thermostat opens at 170 degrees and uses a reverse poppet layout to manage coolant flow through the engine.

This part cross-references Stant 45947 for the same application.

Common Cooling System Issues

• Engine running hotter than normal due to a thermostat that no longer opens at the correct temperature
• Slow warm-up or unstable operating temperature from a worn thermostat spring
• Coolant flow irregularities caused by corrosion or internal thermostat wear
• Air trapped in the cooling system after thermostat service
• Temperature control concerns on 170-degree OE and alternate-temperature applications

Installation Notes and Tips

Verify the vehicle’s required thermostat temperature before installation, since this part is listed for both OE and alternate-temperature applications. Follow the fitment notes for each vehicle; several applications specify that a gasket is not required and silicone should be used instead. Confirm housing condition, clean the sealing surfaces, and inspect the cooling system for contamination before reassembly.

Compatible with 1984-2004 Nissan and INFINITI applications listed in the fitment data, including 1999-2004 Nissan Frontier, 2002-2004 Nissan Xterra, 1996-2000 Nissan Pathfinder, and 1987-1996 Nissan 300ZX.

Quality Assurance

Gates designs this Premium Thermostat line with corrosion-resistant materials and an upgraded spring for improved temperature stability under normal operating conditions. Part number 33737S is built to meet the listed fitment and temperature requirements for the specified vehicles.