Dorman 902-5138 Engine Coolant Thermostat Housing Assembly

Engine Coolant Thermostat Housing for Toyota and Lexus

Dorman 902-5138 is a replacement engine coolant thermostat housing assembly built to match the fit and durability of the original housing on select Toyota and Lexus vehicles. It uses a plastic black housing with an included gasket and thermostat, and it is engineered to handle repeated temperature swings in everyday cooling system service.

Compatible With Toyota Corolla, Toyota Prius, Toyota Prius AWD-e, Toyota Prius Prime, Toyota Prius V, Toyota Prius Plug-In, and Lexus CT200h applications that call for this housing style. This part cross-references Gates 34707 for the same application.

Key Features

• Engine coolant thermostat housing assembly with integrated cover
• Plastic black construction for OE-style replacement fit
• Includes thermostat and gasket for the listed application
• 180 degree F thermostat opening temperature
• Three mounting holes and two outlet ports
• Designed for select Toyota Prius, Corolla, and Lexus CT200h cooling systems
• Dorman 902-5138 replacement part number for catalog and service matching

Detailed Description

This thermostat housing assembly is designed for vehicles that use an integrated coolant outlet and thermostat layout. The housing dimensions, flange layout, and port configuration are matched to the original design so the part installs in the same location and supports proper coolant flow control. Dorman 902-5138 is a practical replacement for high-mileage cooling system repairs on Toyota Prius, Toyota Corolla, and Lexus CT200h models listed in the fitment data.

The assembly includes the thermostat and gasket, which helps simplify service when replacing a worn or leaking housing. The 180 degree F thermostat opening temperature supports normal engine warm-up and temperature regulation for the specified applications. Dorman 902-5138 is also a useful catalog reference when searching for a Toyota Prius thermostat housing assembly or Lexus CT200h engine coolant thermostat housing replacement.

Common Problems This Part Can Address

• Coolant leaks at the thermostat housing or gasket surface
• Cracked or heat-aged plastic housing
• Improper coolant temperature control from a worn thermostat
• Service issues caused by a damaged integrated housing cover
• Cooling system maintenance on select Toyota Prius and Corolla models

Installation Notes and Tips

Verify the housing shape, outlet port count, mounting hole pattern, and thermostat opening temperature before installation. Replace the gasket surface only after the cooling system has been drained and the mating surfaces are clean and free of old seal material. Confirm the vehicle application against the fitment list for Toyota Corolla 2020-2025, Toyota Prius 2010-2025, Toyota Prius AWD-e 2019-2025, Toyota Prius Prime 2017-2025, Toyota Prius V 2012-2018, Toyota Prius Plug-In 2012-2015, and Lexus CT200h 2011-2017.

Quality Assurance

Dorman designs this replacement thermostat housing assembly to match stock fit and durability requirements for the listed vehicles and to withstand extreme temperature changes during normal cooling system operation.