Dorman 603-5104 Engine Coolant Reservoir - Front

Engine Coolant Reservoir for OE Fit

Dorman 603-5104 is a replacement engine coolant reservoir built from plastic to handle underhood heat and engine vibration. It is engineered to match the original part’s fit and function for a direct replacement on compatible applications, including select Honda Civic and Honda Accord cooling system repairs.

Key Features

• Plastic coolant reservoir with clear construction for fluid level visibility
• Pressurized design with a spring-loaded twist cap
• Cap included, rated to 15 psi
• Four mounting holes for OE-style attachment points
• Engineered to match original fit and function
• Includes reservoir, cap, and tubing

Detailed Description

This Dorman coolant reservoir, part number 603-5104, is made for drivers replacing a cracked, leaking, or heat-damaged expansion tank in the cooling system. The clear plastic body helps with coolant inspection, while the pressurized design and included cap support proper system operation. For Honda Civic and Honda Accord cooling repairs, 603-5104 provides an OE-style replacement built to align with the original reservoir layout and mounting points.

This part cross-references Monroe Shocks & Struts (e.g., 575.1033, 2591625C92) for the same application.

Common Problems This Part Can Address

• Coolant loss from a cracked or brittle reservoir
• Visible coolant leaks around the tank or cap area
• Low coolant level warnings caused by reservoir failure
• Pressure loss in the cooling system from a worn cap or damaged tank
• Replacement needs after heat cycling and engine vibration damage

Installation Notes and Tips

Verify the mounting hole layout, cap style, and pressurized reservoir design before installation. Transfer or connect the tubing as required by the vehicle’s cooling system layout, and inspect nearby hoses and clamps for wear while the reservoir is removed. Confirm the application against the vehicle’s year, make, and model before ordering.

Quality Assurance

Dorman manufactures this reservoir from materials selected to withstand underhood heat and vibration. Part number 603-5104 is built to match original fit and function for a direct replacement on compatible Honda Civic and Honda Accord applications.