Motorad 456-187 Engine Coolant Thermostat

OE-Style Cooling Control

Motorad 456-187 is a standard engine coolant thermostat built for precise temperature control in demanding cooling systems. With a 187°F opening temperature, OEM-style seals, and a jiggle pin weep hole, it supports stable coolant flow for a wide range of GM, Cadillac, Buick, Pontiac, Saab, Hummer, and Isuzu applications.

The Motorad Standard line focuses on OE-spec replacement parts made with OEM quality materials and processes. Part number 456-187 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: 187°F for OE-specified thermal control
• Copper case and wax compound for responsive temperature regulation
• Includes thermostat seal; O-ring seal type with rubber sealing material
• Jiggle pin weep hole and air relief valve help purge trapped air where applicable
• Standard design with offset configuration and OEM-style seals where applicable
• Sealing flange outside diameter: 2.13 in; height: 2.56 in
• Bypass diameter: 1.46 in; bypass length: 1.84 in

Detailed Description

Motorad 456-187 is an engine coolant thermostat engineered to match OE specifications for vehicles that require a 187°F thermostat. It is used in applications such as Chevrolet Silverado 1500, Chevrolet Tahoe, Cadillac CTS, Pontiac Grand Prix, and Buick LaCrosse, along with many other GM-platform vehicles listed in the fitment data. The thermostat’s copper case and wax element are selected to react quickly to coolant temperature changes, helping the cooling system maintain consistent operating temperature.

This part cross-references Dorman - Autograde 45687 and Four Seasons 14948 for the same application.

What It Helps Address

• Engine running cooler or hotter than the specified operating range
• Delayed coolant circulation after cold start
• Temperature fluctuation during stop-and-go driving
• Cooling system service on OE-spec thermostat applications
• Replacement of a worn thermostat seal or O-ring

Installation Notes

Verify the 187°F temperature rating and seal style before installation. This thermostat includes a seal and uses an O-ring design; no installation tool is included. Clean the housing mating surfaces, inspect the coolant passages, and confirm the bypass dimensions and flange measurements match the original part before assembly.

Compatible With 1997-2009 Chevrolet Corvette, 1998-2002 Chevrolet Camaro, 1998-2002 Pontiac Firebird, 1999-2003 Chevrolet Silverado 1500, 2000-2003 Chevrolet Tahoe, 2004-2006 GMC Sierra 1500, 2004-2009 Chevrolet Silverado 2500, 2004-2009 Chevrolet Silverado 2500 HD, 2004-2009 Chevrolet Silverado 3500, and 2008-2009 Buick Allure. Additional fitments include Cadillac CTS, Pontiac G8, Saab 9-7x, and Chevrolet Impala applications listed in the fitment table.

Quality Assurance

Motorad manufactures this thermostat with OEM quality materials and safety standards as an OE supplier, using OEM specifications and processes for consistent fit and function in demanding automotive cooling systems.