Dorman M390391 Brake Master Cylinder

Overview of Dorman Brake Master Cylinder for Ford E-350 Econoline

The Dorman M390391 brake master cylinder is designed specifically for Ford E-350 Econoline models, providing reliable brake hydraulics performance. This master cylinder features an aluminum construction and includes a reservoir and sensor to ensure proper brake fluid management and system monitoring.

• Master cylinder bore diameter: 1.25 inches
• Constructed from durable aluminum material
• Includes reservoir and sensor for brake fluid level monitoring
• Two outlet ports with rearward outlet size 7/16-24 and secondary outlet thread diameter 9/16-18
• Package contains the master cylinder only; mounting hardware not included

Detailed Product Description

The Dorman M390391 brake master cylinder is engineered to meet the hydraulic braking needs of Ford E-350 Econoline vehicles. Its 1.25-inch bore diameter ensures proper fluid displacement for effective brake pressure. Made from aluminum, this master cylinder offers corrosion resistance and long service life. The included reservoir allows for adequate brake fluid storage, while the integrated sensor provides real-time fluid level feedback to the vehicle’s monitoring system. Featuring two outlets, the master cylinder supports dual-circuit brake systems, with precise outlet thread sizes of 7/16-24 for the rearward outlet and 9/16-18 for the secondary outlet, ensuring compatibility with factory brake lines.

Common Applications and Issues Addressed

• Restores proper brake fluid pressure in Ford E-350 Econoline brake systems
• Replaces leaking or damaged master cylinders causing brake fluid loss
• Resolves brake pedal sinking or sponginess due to internal seal failure
• Addresses brake warning light activation related to fluid level sensor faults
• Improves overall brake system responsiveness and safety

Installation Notes and Tips

Installation of the Dorman M390391 brake master cylinder requires careful attention to brake fluid handling and bleeding procedures. Since mounting hardware is not included, retain original fasteners or source compatible replacements. Ensure all brake lines are properly connected to the correct outlet ports based on thread size. After installation, thoroughly bleed the brake system to remove air and verify sensor functionality. Professional installation is recommended for accurate fitment and safety compliance.

Quality Assurance and Warranty

Dorman manufactures the M390391 brake master cylinder to meet or exceed OEM specifications for Ford E-350 Econoline vehicles. The aluminum construction and integrated sensor contribute to reliable performance under normal operating conditions. While specific warranty details are not provided here, Dorman typically offers limited warranties covering defects in materials and workmanship. Consult product documentation or the manufacturer for exact warranty terms.