Gates 33959 Engine Coolant Thermostat

Gates 33959 Heavy-Duty Thermostat Overview

The Gates 33959 Heavy-Duty Thermostat is an engine coolant thermostat built for demanding cooling systems in heavy-duty truck, bus, tractor, and equipment service. It uses a steel and copper construction with an O-ring seal and a bottom by-pass design to support stable coolant control in harsh underhood conditions.

Gates Heavy-Duty Thermostat Green Stripe products are built for applications where noise, vibration, and heat cycling place extra stress on the cooling system. If you are servicing a heavy-duty cooling system and need a thermostat with an 180-degree opening temperature, this part number 33959 is a direct replacement option to verify against your application.

Key Features

• Engine coolant thermostat for heavy-duty cooling systems
• 180°F / 82°C start-to-open temperature
• Bottom by-pass design for specified cooling layouts
• Steel and copper construction
• O-ring seal type for sealing at the housing interface
• No jiggle pin weep hole
• No installation tool included
• Gates part number 33959

Detailed Product Description

The Gates 33959 thermostat is engineered for heavy-duty truck, bus, tractor, and off-highway equipment applications where consistent coolant regulation matters. Its bottom by-pass configuration, 2.25-inch valve diameter, 2.87-inch sealing flange outside diameter, and 3.41-inch overall height are important dimensions to confirm during replacement. The thermostat starts to open at 180°F, helping the engine reach and maintain the intended operating temperature range.

This part cross-references Dorman - HELP 14908 for the same application. It is also listed under Gates 33959 and may be referenced in cooling-system service for heavy-duty vehicles such as Ford F-350 and Chevrolet Silverado HD when the OE application calls for this thermostat design and temperature rating.

What This Thermostat Helps Address

• Engine running too cool or too hot due to thermostat wear
• Delayed warm-up after cold starts
• Temperature fluctuation from a sticking thermostat
• Cooling-system service on heavy-duty truck, bus, tractor, or equipment engines
• Replacement needs where the original thermostat uses a bottom by-pass layout

Installation Notes and Tips

Confirm the thermostat housing style, by-pass configuration, flange dimensions, and opening temperature before installation. Clean the sealing surfaces thoroughly and inspect the O-ring groove and housing for corrosion or distortion. Because no installation tool is included, use the correct service tools for your cooling system and refill the system with the proper coolant mixture after installation. Verify operation by checking engine warm-up and coolant temperature stability during road test or load test conditions.

Quality Assurance

Gates Heavy-Duty Thermostat Green Stripe components are built for the vibration, heat, and duty-cycle demands common in commercial and off-highway service. The Gates 33959 is specified with steel and copper materials and dimensions intended for accurate thermostat replacement in the correct application.