Motorad 447-185 Engine Coolant Thermostat - Front

Engine Coolant Thermostat for GM HD Applications

The Motorad Standard 447-185 engine coolant thermostat is built for OE-style temperature control in demanding cooling systems. It opens at 185°F and includes a rubber O-ring seal for a direct replacement on a wide range of Chevrolet Silverado, GMC Sierra, Express, Savana, and Hummer H1 applications.

Motorad Standard focuses on OE-spec thermostat construction for consistent coolant flow and stable operating temperature. This 447-185 thermostat uses a copper case and wax compound for quick reaction to coolant temperature changes, along with an offset design and air relief valve where applicable.

Key Features

• Start-to-open temperature: 185°F
• Standard thermostat design with OE-style sealing
• Copper case and wax compound for responsive temperature regulation
• Rubber O-ring seal included
• Offset design with air relief valve where applicable
• Sealing flange outside diameter: 2.13 in
• Bypass diameter: 1.18 in
• Bypass length: 1.36 in
• Flange thickness: 0.05 in

Detailed Description

Motorad 447-185 is an engine coolant thermostat engineered to match OEM specifications and manufacturing processes. It is built with OEM-quality materials and safety standards as supplied by an OE supplier, making it a practical choice for maintaining proper coolant circulation in GM trucks and vans. The 185-degree opening temperature supports factory-style thermal management for vehicles such as the Chevrolet Silverado 2500 HD, Chevrolet Silverado 3500 HD, GMC Sierra 2500 HD, GMC Sierra 3500 HD, Chevrolet Express 2500, Chevrolet Express 3500, GMC Savana 2500, GMC Savana 3500, and Hummer H1.

This part cross-references AP Exhaust 14728 and 54785 for the same application. The Motorad 447-185 is also listed with OE-style interchange references including 12T99D and 9447185.

What This Thermostat Helps Address

• Engine running too cool or too warm
• Delayed coolant flow after cold starts
• Temperature fluctuation during towing or heavy-duty use
• Cooling system service on GM HD trucks and vans
• Replacement of a worn thermostat seal or housing seal interface

Installation Notes and Tips

Verify the 185°F temperature rating and front-position fitment before installation. Replace the thermostat in the correct orientation and inspect the sealing surface, bypass passage, and coolant condition during service. Use the included O-ring seal and confirm proper seating to help prevent leaks after reassembly.

Quality Assurance

Motorad manufactures this thermostat to OEM specifications using OE-supplier quality materials and processes. The copper case, wax compound, and OE-style sealing approach are intended to meet the demands of factory cooling systems in Chevrolet Silverado, GMC Sierra, Express, Savana, and Hummer H1 applications.

Vehicle Fitment

• Fits 2021-2024 Chevrolet Silverado 2500 HD, front
• Fits 2021-2024 Chevrolet Silverado 3500 HD, front
• Fits 2022-2024 GMC Sierra 2500 HD, front
• Fits 2021-2024 GMC Sierra 3500 HD, front
• Fits 2001-2021 GMC Sierra 2500 HD, front; Temperature 185F; Includes thermostat, seal; OE Specified; Standard
• Fits 2001-2020 Chevrolet Silverado 2500 HD, front; Temperature 185F; Includes thermostat, seal; OE Specified; Standard
• Fits 2007-2020 Chevrolet Silverado 3500 HD, front; Temperature 185F; Includes thermostat, seal; OE Specified; Standard
• Fits 2007-2020 GMC Sierra 3500 HD, front; Temperature 185F; Includes thermostat, seal; OE Specified; Standard
• Fits 2006-2016 Chevrolet Express 2500, front; Temperature 185F; Includes thermostat, seal; OE Specified; Standard
• Fits 2006-2016 Chevrolet Express 3500, front; Temperature 185F; Includes thermostat, seal; OE Specified; Standard
• Fits 2006-2016 GMC Savana 2500, front; Temperature 185F; Includes thermostat, seal; OE Specified; Standard
• Fits 2006-2016 GMC Savana 3500, front; Temperature 185F; Includes thermostat, seal; OE Specified; Standard
• Fits 2007 Chevrolet Silverado 2500 HD Classic, front; Temperature 185F; Includes thermostat, seal; OE Specified; Standard
• Fits 2007 Chevrolet Silverado 3500 Classic, front; Temperature 185F; Includes thermostat, seal; OE Specified; Standard
• Fits 2007 GMC Sierra 2500 HD Classic, front; Temperature 185F; Includes thermostat, seal; OE Specified; Standard
• Fits 2007 GMC Sierra 3500 Classic, front; Temperature 185F; Includes thermostat, seal; OE Specified; Standard
• Fits 2001-2006 Chevrolet Silverado 3500, front; Temperature 185F; Includes thermostat, seal; OE Specified; Standard
• Fits 2001-2006 GMC Sierra 3500, front; Temperature 185F; Includes thermostat, seal; OE Specified; Standard
• Fits 2006 Hummer H1, front; Temperature 185F; Includes thermostat, seal; OE Specified; Standard