Dorman 926-390 4WD Vacuum Check Valve

4WD Vacuum Check Valve Overview

Dorman 926-390 is a 4WD vacuum check valve built to match the original valve’s fit and function in the vacuum-operated 4WD system. It helps maintain proper vacuum levels for 4WD hub lock operation on select Ford and Lincoln applications, including Ford F-150, Ford Expedition, and Lincoln Navigator.

• Direct-fit 4WD vacuum check valve for vacuum hub lock systems
• Black EPDM construction for durability in underhood environments
• Round connector shape with 3 ports
• Port sizes: 10 mm maximum diameter, 5 mm and 3 mm port outside diameters
• Length: 8 in.; outer diameter: 0.39 in.
• Fits select 2015-2020 Ford F-150, 2018-2021 Ford Expedition, and 2018-2021 Lincoln Navigator applications

Fitment and Application Details

Use Dorman 926-390 when servicing a vacuum-controlled 4WD hub lock system that requires stable one-way vacuum flow. This part cross-references Standard Ignition HVH005 for the same application. Confirm the vehicle’s vacuum routing and connector dimensions before installation to ensure the correct replacement.

Fits 2015-2020 Ford F-150, 4WD Vacuum Hub Lock. Fits 2018-2021 Ford Expedition, 4WD Vacuum Hub Lock. Fits 2018-2021 Lincoln Navigator, 4WD Vacuum Hub Lock.

Common Issues This Part Can Address

• Loss of vacuum pressure in the 4WD hub lock circuit
• Delayed or inconsistent 4WD engagement
• Vacuum bleed-back through a worn check valve
• Incorrect vacuum retention in hub lock plumbing
• Faulty valve operation caused by age, heat, or contamination

Installation Notes and Tips

Inspect the vacuum hoses, fittings, and routing before installing Dorman 926-390. Match the connector shape and port sizes to the original valve, and verify the valve orientation so vacuum flows in the correct direction. After installation, test 4WD hub lock operation and check for vacuum leaks.

Quality Assurance

Dorman engineers this 4WD vacuum check valve to match the original part’s fit and function for the listed applications. It is built for direct replacement use in the vehicle’s vacuum-operated 4WD system.