Dorman 902-5101 Engine Coolant Reservoir Cap

Engine Coolant Reservoir Cap Replacement

Dorman 902-5101 is a direct replacement engine coolant reservoir cap for vehicles that need a cracked, missing, or worn coolant tank cap restored to proper function. This pressurized twist-on cap is built from black plastic with a 76.2 mm diameter and a 10 psi pressure rating for a secure seal on the coolant reservoir.

Use this Dorman coolant reservoir cap when servicing cooling system leaks or replacing a damaged cap on applications such as Ford F-250 and Ford F-350 models that use this style of reservoir cap. Part number 902-5101 is also referenced by 4C4Z8100A and 572.2005 for the same application.

Key Features

• Direct replacement engine coolant reservoir cap
• Twist-on attachment type for straightforward installation
• Pressurized design with 10 psi maximum pressure rating
• Black plastic construction
• 76.2 mm diameter for proper reservoir fit
• No vent and no pressure release lever

Detailed Description

This coolant tank cap is engineered to replace the original cap on the reservoir without changing the system design. Its pressurized, non-vented construction helps maintain the cooling system’s intended pressure level, while the twist-on design provides a simple locking action at the reservoir neck. For Ford F-250 and Ford F-350 owners, Dorman 902-5101 offers a practical replacement when the original cap is cracked, lost, or no longer sealing correctly. The same part number, 902-5101, is commonly used as a direct-fit coolant reservoir cap replacement in applications that call for a 76.2 mm, 10 psi twist cap.

Common Problems This Part Can Address

• Coolant reservoir cap cracked or broken
• Cap missing from the coolant tank
• Loss of pressure at the reservoir cap seal
• Coolant odor or residue around the reservoir neck
• Cooling system warning caused by a poor cap seal

Installation Notes and Tips

Inspect the reservoir neck and sealing surface before installation. Confirm the cap diameter, twist-on style, and 10 psi pressure rating match the original part before use. Install by aligning the cap and turning it until it seats securely; do not force the cap if the threads or neck are damaged.

Quality Assurance

Dorman designs this replacement cap to match the original fit and function of the factory coolant reservoir cap. Part number 902-5101 is built as a direct replacement for the specified application and cross-references 4C4Z8100A and 572.2005.