Dorman 54209 Engine Coolant Reservoir Cap

Engine Coolant Reservoir Cap Replacement

Replace a cracked, missing, or worn coolant reservoir cap with this direct-fit Dorman replacement. Built from black plastic with a press-on, flip-top design, it restores a secure closure for the reservoir opening and matches the original style for a clean service repair.

Fits 2006-2014 Ford Explorer, 2007-2010 Ford Explorer Sport Trac, 2009-2014 Ford Expedition, 2011-2014 Ford F-150, 2010-2012 Ford Fusion, 2011-2012 Lincoln MKZ, 2009-2014 Lincoln Navigator, 2010-2011 Mercury Milan, and 2006-2010 Mercury Mountaineer. Part number 54209 is also a direct replacement for OE reference 9L3Z8K103A.

Key Features

• Direct replacement engine coolant reservoir cap
• Black plastic construction
• Press-on attachment with flip-top design
• Non-vented and non-pressurized cap design
• 31.6 mm diameter for proper reservoir fit
• Low-profile dimensions: 1.438 in long and 2.25 in wide

Detailed Product Description

Dorman 54209 is engineered as a direct replacement cap for the coolant reservoir opening on the listed Ford, Lincoln, and Mercury applications. The cap is designed to restore the original sealing and closure function after the factory cap has cracked, gone missing, or no longer fits securely. Its press-on, flip-top layout and 31.6 mm diameter support a straightforward service replacement on the specified vehicles, including Ford Expedition, Ford F-150, and Lincoln Navigator applications.

This part number 54209 is built in black plastic and follows the original-style reservoir cap format for a clean, OE-like repair. It cross-references OE part number 9L3Z8K103A for the same application.

What It Helps Fix

• Broken or cracked coolant reservoir cap
• Missing reservoir cap after service or repair
• Loose cap that no longer stays seated
• Damaged cap threads or retaining surfaces on the reservoir opening
• Improper closure at the coolant reservoir fill point

Installation Notes and Tips

Confirm the reservoir opening style and diameter before installation. This cap uses a press-on attachment and flip-top design, so it should seat fully and evenly on the reservoir neck. Verify vehicle application by year, make, and model before ordering, especially on Ford F-150, Ford Expedition, and Lincoln Navigator vehicles.

Quality Assurance

Dorman designs this replacement cap to match the original fit and function for the listed applications, helping restore proper reservoir closure with a direct-fit service part.