Dorman 902-5403 Engine Coolant Reservoir Cap

Engine Coolant Reservoir Cap Replacement

Replace a cracked, missing, or worn coolant reservoir cap with a direct-fit Dorman solution built for a secure twist-on seal. Dorman 902-5403 is a black plastic engine coolant reservoir cap with a 49 mm diameter, made to restore proper closure at the coolant tank.

For drivers searching for an engine coolant reservoir cap for Honda Civic or Toyota Corolla applications, this direct replacement helps return the cooling system to normal service without changing the reservoir itself. Part number 902-5403 is also referenced by cross numbers such as CALORSTAT by Vernet RC0050.

Key Features

• Direct replacement engine coolant reservoir cap for the coolant tank
• Twist-on attachment type for straightforward installation and removal
• 49 mm diameter for the specified reservoir opening
• Black plastic construction for a factory-style appearance
• Non-pressurized, non-vented design with no pressure release lever
• Engineered to replace a lost or damaged original cap

Product Details

Dorman 902-5403 is a twist-style coolant reservoir cap designed to close the expansion tank securely and help maintain the reservoir’s sealed condition. The cap’s plastic construction, 49 mm size, and direct-replacement format make it a practical choice when the original cap is cracked, stripped, or no longer sealing correctly. If you are looking for a coolant reservoir cap replacement for Honda Civic or Toyota Corolla service work, 902-5403 provides a straightforward OE-style solution.

This part cross-references CALORSTAT by Vernet RC0050 for the same application.

Common Problems It Can Help Solve

• Broken or cracked coolant reservoir cap
• Cap that no longer twists on securely
• Missing cap after service or repair
• Loose closure at the coolant expansion tank
• Visible wear on the original reservoir cap

Installation Notes and Tips

Confirm the reservoir opening diameter before ordering and compare the original cap’s style, size, and attachment method to Dorman 902-5403. Clean the tank neck and sealing surface before installing the new cap, then twist it on until fully seated. For best results, inspect the coolant reservoir and surrounding cooling system components for cracks, leaks, or damage while the cap is removed.

Quality Assurance

Dorman manufactures replacement parts to match original equipment form and function where specified. Part number 902-5403 is built as a direct replacement coolant reservoir cap for service-focused repairs.