Four Seasons 86131 Engine Coolant Thermostat Housing

Thermostat Housing for Audi and Volkswagen

Four Seasons Thermostat Housing 86131 is an engine coolant thermostat housing built for select Audi and Volkswagen applications. It is a plastic, OE-style replacement housing that meets or exceeds OEM requirements and is supplied without a thermostat or gasket/seal.

Use this housing when servicing the cooling system on Audi A4, A6, S4, Cabriolet, Allroad Quattro, and Volkswagen Passat models that call for this style of thermostat housing. Four Seasons 86131 is sized for the factory coolant connection points and supports direct replacement service on the listed vehicles.

Key Features

• Plastic thermostat housing for engine coolant service
• Style: without thermostat
• Gasket or seal not included
• Meets or exceeds OEM specifications
• Inlet port diameter: 1.25 in.
• Bolt hole center to bolt hole center: 3.21 in.
• Flange thickness: 0.52 in.
• Overall height: 3.55 in.

Product Details

Four Seasons 86131 is part of the Thermostat Housing line and is engineered as an engine coolant components replacement for vehicles that use a plastic thermostat housing assembly. The housing is supplied without a thermostat, allowing you to reuse or replace the thermostat separately as needed. This part cross-references Genuine 078121121K and URO 078121121J for the same application. The Four Seasons 86131 part number is also used in interchange listings for related aftermarket and OE-reference applications.

What It Helps Repair

• Coolant leaks at the thermostat housing
• Cracked or warped plastic housing surfaces
• Improper sealing at the coolant outlet
• Overheating caused by housing failure
• Service issues during thermostat replacement on Audi and Volkswagen cooling systems

Installation Notes

• Verify the housing matches the original inlet diameter, bolt spacing, and flange dimensions before installation.
• Inspect the mating surfaces and replace the thermostat and seal components as required by the repair.
• Confirm vehicle-specific fitment for Audi A4, A6, S4, Cabriolet, Allroad Quattro, and Volkswagen Passat applications.
• Fits 1995 Audi 90, N/A.
• Fits 1995 Audi 90 Quattro, N/A.
• Fits 1995-1998 Audi Cabriolet, N/A.
• Fits 1996-2001 Audi A4, N/A.
• Fits 1996-2001 Audi A4 Quattro, N/A.
• Fits 1996-2001 Audi A6, N/A.
• Fits 1996-2001 Audi A6 Quattro, N/A.
• Fits 1998-2000 Volkswagen Passat, N/A.
• Fits 2000-2002 Audi S4, N/A.
• Fits 2001 Volkswagen Passat, N/A.
• Fits 2001-2005 Audi Allroad Quattro, N/A.
• Fits 2002-2004 Audi A6 Quattro, N/A.
• Fits 2002-2005 Volkswagen Passat, N/A.

Quality Assurance

Four Seasons manufactures this thermostat housing to meet or exceed OEM specifications for the listed applications. The part is built for direct-fit cooling system service on compatible Audi and Volkswagen models, including Audi A4, A6, S4, and Volkswagen Passat platforms.