Dorman M390186 Brake Master Cylinder

Reliable Brake Master Cylinder for Buick, Cadillac, Oldsmobile, and Pontiac

The Dorman M390186 Brake Master Cylinder is engineered to restore proper brake hydraulics in select Buick, Cadillac, Oldsmobile, and Pontiac models. Designed with precision, this master cylinder ensures consistent brake fluid pressure for safe and responsive braking performance.

• Master cylinder bore diameter: 1 inch for accurate fluid displacement
• Constructed from durable aluminum material for corrosion resistance
• Includes reservoir and sensor for complete brake system integration
• Two outlet ports with rearward outlet size M10 x 1.0 and secondary outlet thread diameter M12 x 1.0
• Thread pitch of 1.0 for secure and proper fitting
• Package contains the master cylinder unit; mounting hardware not included

Detailed Product Features and Specifications

The Dorman M390186 master cylinder is crafted from aluminum, providing a lightweight yet robust component that resists corrosion and wear. Its 1-inch bore diameter is designed to deliver precise hydraulic pressure, essential for the braking systems of vehicles such as the Buick LeSabre, Cadillac DeVille, Oldsmobile 88, and Pontiac Bonneville. The included reservoir and sensor facilitate seamless integration with the vehicle’s brake fluid monitoring system, ensuring timely alerts for fluid levels. Featuring two outlets, the master cylinder supports dual-circuit brake systems, with outlet sizes tailored for secure connections: a rearward outlet sized M10 x 1.0 and a secondary outlet with M12 x 1.0 threading. This part is identified by part number M390186 and is compatible with models including the Buick Park Avenue, Cadillac Fleetwood, Oldsmobile Delta 88, and Pontiac Riviera.

Common Applications and Problem Resolution

• Restores brake fluid pressure in vehicles experiencing spongy or unresponsive brakes
• Replaces master cylinders with leaking or damaged reservoirs
• Addresses brake warning light activation due to faulty sensors
• Solves issues related to inconsistent brake pedal feel or travel
• Supports brake system repairs in Buick, Cadillac, Oldsmobile, and Pontiac models listed

Installation Notes and Tips

Installation of the Dorman M390186 master cylinder requires proper brake system bleeding to remove air and ensure optimal hydraulic function. Note that mounting hardware is not included, so retain original fasteners or acquire appropriate replacements. Verify thread pitch and outlet sizes (M10 x 1.0 and M12 x 1.0) to ensure compatibility with existing brake lines. Sensor connections should be carefully reattached to maintain brake fluid level monitoring. Professional installation is recommended for accurate fitment and safety compliance.

Quality Assurance and Warranty Information

Dorman manufactures the M390186 master cylinder to meet or exceed OEM specifications for the specified Buick, Cadillac, Oldsmobile, and Pontiac models. The aluminum construction and integrated sensor contribute to long-term reliability. While mounting hardware is not included, the product undergoes rigorous quality control to ensure proper function upon installation. Warranty coverage details should be confirmed with the distributor or manufacturer to understand terms and conditions.