Dorman 902-991 Engine Coolant Thermostat Housing - Engine Block

Overview of Dorman Engine Coolant Thermostat Housing 902-991

The Dorman 902-991 engine coolant thermostat housing is designed for reliable cooling system performance in select Audi and Volkswagen models. Constructed from durable black plastic, this thermostat housing ensures proper coolant flow and temperature regulation for your vehicle.

• Material: High-quality black plastic for corrosion resistance
• Includes gasket and O-rings for secure sealing
• Two mounting holes with 0.313-inch diameter for precise fitment
• Housing neck angled at 45 degrees from base for optimal coolant routing
• Compatible with Audi A4, A4 Quattro, A6, A6 Quattro, and Volkswagen Passat

Detailed Product Description

The Dorman 902-991 engine coolant thermostat housing is engineered to meet the specifications of your Audi or Volkswagen cooling system. Made from durable plastic, it resists corrosion and heat damage commonly found in engine compartments. The housing includes a gasket and O-rings to ensure a tight seal, preventing coolant leaks and maintaining system pressure. With two mounting holes sized at 0.313 inches in diameter, installation aligns accurately with factory mounting points. The 45-degree neck angle facilitates proper coolant flow direction, supporting efficient engine temperature control. This housing does not include a thermostat or bolts, allowing for compatibility with existing components.

Compatible Vehicles and Applications

• Designed specifically for Audi A4 and A4 Quattro models
• Fits Audi A6 and A6 Quattro vehicles
• Compatible with Volkswagen Passat models requiring this thermostat housing

Common Issues Addressed by This Thermostat Housing

• Prevents coolant leaks caused by cracked or damaged housings
• Eliminates overheating due to improper coolant flow
• Resolves coolant contamination from failed seals
• Replaces warped or deteriorated plastic housings
• Supports stable engine temperature regulation for improved performance

Installation Notes and Tips

Ensure the engine is cool before beginning installation to avoid injury from hot coolant. Remove the old thermostat housing carefully, inspecting the mounting surface for debris or damage. Replace the gasket and O-rings included with the Dorman 902-991 to maintain a proper seal. Torque mounting bolts to manufacturer specifications (bolts not included). Verify the 45-degree neck angle aligns with existing coolant hoses for proper fitment. After installation, refill the cooling system and bleed air as necessary to prevent overheating.

Quality Assurance and Warranty

Dorman parts are manufactured to meet or exceed OEM standards for fit, form, and function. The 902-991 thermostat housing undergoes quality inspections to ensure durability and performance. This part includes a gasket and O-rings to support leak-free operation. While bolts and thermostat are not included, the housing is designed for compatibility with factory components. Please refer to Dorman's warranty policy for specific coverage details.