Dorman 902-5121 Engine Coolant Thermostat Housing

Engine Coolant Thermostat Housing for BMW

This Dorman engine coolant thermostat housing is a direct replacement for specified BMW cooling system applications. Built from metal with a natural finish, it matches the stock housing’s fit and durability requirements for BMW 325i, 325iX, 525i, 528e, and 325e models.

Key Features

• Metal construction for strength and heat resistance
• Natural finish
• Outlet port diameter: 1.467 in.
• Three mounting holes with OE-style bolt pattern
• Flange thickness: 0.565 in.
• Designed to match stock thermostat housing fit and service life expectations
• Part number 902-5121 for easy identification

Detailed Description

Dorman 902-5121 is an engine coolant thermostat housing engineered for BMW cooling system service where the original housing has cracked, warped, or no longer seals correctly. The metal housing is built to match the original fit on select BMW 325i, 325iX, 525i, 528e, and 325e applications, including 1992-1993 BMW 325i and 1982-1988 BMW 528e. This thermostat housing supports proper coolant routing at the thermostat location and is shaped for the specified three-bolt mounting pattern.

This part cross-references Four Seasons 85066 and Motorad CH5066 for the same application. If you are replacing a BMW 325i thermostat housing or servicing a BMW 528e cooling system, 902-5121 provides a direct-fit housing option without the thermostat, gasket, seals, or bolts included.

What It Helps Fix

• Coolant leaks at the thermostat housing
• Cracked or warped original housing
• Improper sealing at the thermostat mounting area
• Cooling system service issues caused by housing corrosion or damage
• Fitment problems from worn OE-style plastic or aging metal housings

Installation Notes and Tips

Verify the three-bolt pattern, outlet port diameter, and mounting dimensions before installation. Transfer or source the thermostat, gasket or seal, and any required bolts separately, since they are not included. Clean the mating surfaces thoroughly and inspect the cooling system for related wear before reassembly. Fits 1992-1993 BMW 325i, N/A; Fits 1987-1991 BMW 325i, N/A; Fits 1988-1991 BMW 325iX, N/A; Fits 1989-1990 BMW 525i, N/A; Fits 1982-1988 BMW 528e, N/A; Fits 1985-1987 BMW 325e, N/A.

Quality Assurance

Dorman designs replacement cooling system components to match the fit and durability of the original part on specified vehicles. Part number 902-5121 is built for direct replacement use on listed BMW applications.