Dorman 54216 Engine Coolant Reservoir Cap

Engine Coolant Reservoir Cap Replacement

Dorman 54216 is a direct replacement engine coolant reservoir cap for vehicles that need a precise, threaded twist-style cap with a vented, pressurized design. Built from black plastic and rated to 18 psi, it restores the sealing function of a cracked, missing, or worn coolant reservoir cap.

This Dorman 54216 coolant cap is sized at 49.5 mm in diameter and is shaped for a secure threaded attachment. It is a practical OE-style replacement for drivers servicing Buick Lucerne, Cadillac DTS, Chevrolet Corvette, and Cadillac XLR applications listed below.

Key Features

• Direct replacement engine coolant reservoir cap
• Threaded twist-on design for secure installation
• Vented and pressurized construction
• Black plastic housing
• 18 psi maximum pressure rating
• 49.5 mm diameter for proper reservoir fit
• Fits Buick Lucerne, Cadillac DTS, Chevrolet Corvette, and Cadillac XLR applications listed in the fitment data

Product Details

When the original reservoir cap is cracked, lost, or no longer sealing correctly, cooling system pressure control can be affected. Dorman 54216 is engineered as a direct replacement cap to restore the reservoir’s closed, pressurized function and maintain the intended vented operation. This part number 54216 is a straightforward service replacement for vehicles that use the specified coolant reservoir cap design, including 2006-2011 Buick Lucerne, 2006-2011 Cadillac DTS, 2005-2010 Chevrolet Corvette, and 2004-2009 Cadillac XLR.

This part cross-references 10305080 for the same application.

What It Helps Address

• Cracked coolant reservoir cap
• Lost or missing reservoir cap
• Improper sealing at the coolant reservoir
• Pressure loss at the cooling system reservoir
• Cap wear that affects vented, pressurized operation

Installation Notes

Verify the reservoir opening diameter and cap style before installation. This cap uses a threaded twist attachment and should be installed by hand until fully seated. Confirm that the reservoir neck and sealing surfaces are clean and undamaged so the cap can seal correctly. For fitment, use the vehicle-specific listings for 2006-2011 Buick Lucerne, 2006-2011 Cadillac DTS, 2005-2010 Chevrolet Corvette, and 2004-2009 Cadillac XLR.

Quality Assurance

Dorman manufactures direct replacement parts to match the original service function and fit requirements of the application. Part number 54216 is built to the listed specifications, including a 49.5 mm diameter and 18 psi pressure rating, for consistent coolant reservoir cap replacement.