Four Seasons 85959 Engine Coolant Thermostat Housing

Four Seasons 85959 Thermostat Housing

Four Seasons 85959 is an integrated engine coolant thermostat housing built for BMW cooling system service. It combines the thermostat housing and thermostat in one aluminum assembly, with a gasket or seal included for a cleaner replacement on select BMW 540i, 740i, and 740iL applications.

Compatible with 1995-1998 BMW 540i, 740i, and 740iL applications, this Four Seasons thermostat housing is specified to meet or exceed OEM requirements. The Four Seasons Thermostat Housing line focuses on direct-fit engine coolant components for accurate replacement and dependable cooling system repair.

Key Features

• Integrated thermostat housing design for engine coolant service
• Aluminum construction for corrosion-resistant cooling system use
• Thermostat included
• Gasket or seal included
• 4 mounting holes for OE-style installation
• Outlet port diameter: 42.000
• Inlet port diameter: 1.334
• Flange thickness: 0.409
• Meets or exceeds OEM specifications

Detailed Description

Four Seasons 85959 is an engine coolant thermostat housing assembly engineered for BMW cooling system repair where the thermostat and housing are serviced together. The aluminum housing is built with an integrated thermostat, a 4-hole mounting pattern, and included sealing components to support a proper coolant connection at the engine outlet. This part cross-references Gates 34727 for the same application.

Fits 1998 BMW 540i, N/A; 1998 BMW 740i, N/A; 1998 BMW 740iL, N/A; 1997 BMW 540i, N/A; 1995 BMW 540i, N/A; 1997 BMW 740i, N/A; 1995 BMW 740i, N/A; and 1995-1997 BMW 740iL, N/A. Use Four Seasons 85959 when replacing a worn or leaking thermostat housing on these BMW 540i, 740i, and 740iL models.

Common Repair Uses

• Coolant leaks at the thermostat housing
• Cracked or warped aluminum housing surfaces
• Sticking thermostat causing temperature control issues
• Failed housing seal or gasket seepage
• Cooling system service on BMW 540i, 740i, and 740iL models

Installation Notes and Tips

Confirm engine fitment by year and model before installation. Inspect the mating surface, coolant hoses, and adjacent cooling system components before assembly. Replace coolant and bleed the system according to BMW service procedures after installing the thermostat housing. Verify port alignment and mounting-hole spacing during fitment checks.

Quality Assurance

Four Seasons 85959 is listed as meeting or exceeding OEM requirements for the specified BMW applications. The integrated thermostat housing design and aluminum construction support direct replacement service for BMW 540i, 740i, and 740iL cooling system repairs.