Dorman M12578 Brake Master Cylinder

Overview of the Dorman Brake Master Cylinder M12578

The Dorman Brake Master Cylinder M12578 is designed for reliable brake hydraulics performance in select Mercury and Nissan vehicles. Specifically compatible with the Mercury Villager and Nissan Quest models, this master cylinder ensures precise brake fluid control for safe stopping power.

• Master cylinder bore diameter: 1 inch
• Constructed from durable aluminum material
• Includes two outlets with a rearward outlet size of M10 x 1.0
• Secondary outlet thread diameter: 10 mm with a 1.0 thread pitch
• Package contains the master cylinder only; mounting hardware and reservoir are not included
• No sensor included

Detailed Product Description

The Dorman M12578 brake master cylinder is engineered with a 1-inch bore diameter to provide consistent hydraulic pressure for the braking system. Its aluminum construction offers corrosion resistance and lightweight durability, suitable for the brake hydraulics system in Mercury Villager and Nissan Quest vehicles. Featuring two outlets, including a rearward outlet sized M10 x 1.0, this master cylinder supports efficient brake fluid distribution. The secondary outlet thread diameter of 10 mm with a 1.0 thread pitch ensures compatibility with standard brake line fittings. Note that this part does not include mounting hardware or a reservoir, so these components must be sourced separately if needed.

Compatible Vehicles and Applications

This brake master cylinder is compatible with the following vehicles:

• Mercury Villager
• Nissan Quest

It is designed to replace the original equipment master cylinder in these models, restoring proper brake hydraulic function and pedal feel.

Common Issues Addressed by This Master Cylinder

• Brake pedal sinking or sponginess due to internal leaks
• Loss of hydraulic pressure affecting braking performance
• Brake fluid leakage from a worn or damaged master cylinder
• Uneven brake application between front and rear brakes
• Failure of the original master cylinder causing brake warning lights

Installation Notes and Tips

• Ensure the brake system is properly bled after installation to remove air
• Verify thread pitch and outlet sizes match existing brake lines (M10 x 1.0 rearward outlet)
• Mounting hardware and reservoir must be reused or purchased separately
• Inspect brake lines and fittings for wear or damage during replacement
• Follow vehicle-specific service manual instructions for safe installation

Quality Assurance and Warranty

Dorman manufactures the M12578 brake master cylinder to meet or exceed OEM specifications for fit and function. The aluminum construction provides corrosion resistance for extended service life. While mounting hardware and sensors are not included, the master cylinder is tested for hydraulic integrity before shipment. Warranty coverage details should be confirmed through the original product documentation or Dorman's official resources.