Dorman 902-778 Engine Coolant Thermostat Housing - Inner

Engine Coolant Thermostat Housing

Dorman 902-778 is a replacement engine coolant thermostat housing for select Ford, Mazda, Mercury, and Lincoln vehicles. It matches the stock housing’s fit and durability requirements and is built to handle repeated temperature swings in the cooling system.

Compatible With 2002-2006 Mazda MPV, Inner housing; 2003-2008 Mazda 6, Inner housing; 2005-2008 Ford Escape, Inner housing; 2005-2008 Mercury Mariner, Inner housing; 2005-2006 Mazda Tribute, Inner housing; 2006-2009 Ford Fusion, Inner housing; 2006-2009 Mercury Milan, Inner housing; 2006 Lincoln Zephyr, Inner housing; 2008-2011 Mazda Tribute, Inner housing.

• Plastic housing with black finish
• Outlet port diameter: 1.5 in.
• 90-degree housing neck angle
• Three mounting holes with 0.188 in. mounting hole diameter
• Gasket included
• No thermostat included
• No bleeder valve, O-rings, or bolts included

Detailed Description

This Dorman thermostat housing is engineered as a direct replacement for the original engine coolant thermostat housing on the listed applications. The plastic construction and sealed design support cooling-system service on vehicles such as the Mazda 6, Ford Escape, and Ford Fusion, where a properly sealed housing is critical for stable coolant flow and temperature control. Part number 902-778 is also cross-referenced with Motorad CH8778 for the same application.

Common Cooling System Issues

• Coolant leaks at the thermostat housing
• Cracked or warped plastic housing surfaces
• Improper sealing at the gasket interface
• Cooling system service on a worn OE housing
• Fitment replacement for an inner thermostat housing location

Installation Notes

Verify the vehicle application and inner housing location before installation. Transfer or replace the thermostat separately, since this housing does not include one. Inspect the mating surfaces, install the included gasket, and confirm the outlet port and 90-degree neck orientation match the original part. Part number 902-778 is also listed under interchange references including SK902778.

Quality Assurance

Dorman designs this replacement housing to match the fit and durability of the stock thermostat housing and to withstand extreme temperature changes for extended service life.