Dorman 902-990 Engine Coolant Thermostat Housing - Water Pump

Engine Coolant Thermostat Housing

Dorman 902-990 is a replacement engine coolant thermostat housing for specified Audi and Volkswagen applications. It is built from black plastic with a 45-degree neck angle, a 1.5-inch outlet port, and an included gasket/seal and O-ring for a direct-fit cooling system repair.

Compatible With Audi A4, Audi A4 Quattro, Volkswagen Passat, Audi 4000, Volkswagen Vanagon, and Volkswagen Quantum applications listed below, this thermostat housing is engineered to match the fit and durability of the original housing while handling repeated temperature swings in the cooling system.

Key Features

• Brand: Dorman
• Part number: 902-990
• Engine coolant thermostat housing for the cooling system
• Black plastic construction
• 1.5-inch outlet port diameter
• 45-degree housing neck angle from base
• Gasket/seal included
• O-ring included
• Two mounting holes with 0.35-inch diameter
• No thermostat included
• No bleeder valve

Detailed Description

Dorman 902-990 is a replacement water outlet housing designed for vehicles that use a thermostat housing at the water pump location. The housing is shaped to match the original fit and mounting layout, with two mounting holes and an integrated sealing design to help maintain a secure coolant connection. Its plastic construction and temperature-resistant design support long-term service in demanding engine cooling conditions.

This part cross-references Motorad CH9990 for the same application. It is a practical choice for Audi A4 thermostat housing replacement, Audi A4 Quattro cooling system service, and Volkswagen Passat water pump housing repair where the original housing has cracked, warped, or begun leaking.

What It Helps Fix

• Coolant leaks at the thermostat housing
• Cracked or brittle plastic housing damage
• Warped sealing surfaces that allow seepage
• Failed water outlet connection at the cooling system
• Loss of proper coolant flow control at the housing

Installation Notes and Tips

Verify the outlet port diameter, neck angle, and mounting-hole layout against the original housing before installation. Transfer the thermostat if your vehicle setup requires reuse, since the thermostat is not included. Clean the mating surfaces thoroughly and inspect adjacent hoses, clamps, and seals for wear before reassembly.

Fits 1996-2001 Audi A4, Water Pump; 1996-2000 Audi A4 Quattro, Water Pump; 1998-2000 Volkswagen Passat, Water Pump; 1980-1984 Audi 4000, Water Pump; 1982-1984 Volkswagen Vanagon, Water Pump; and 1982-1983 Volkswagen Quantum, Water Pump.

Quality Assurance

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