* Wheel Cylinder: This is the most common cause. The wheel cylinder is a small hydraulic cylinder located behind the brake drum (if it's drum brakes) or integrated into the caliper (if it's disc brakes). It pushes the brake shoes (drum) or pads (disc) against the drum or rotor to stop the wheel. A leaking wheel cylinder means the seals inside are worn out and allowing brake fluid to escape.
* Brake Hose: The rubber brake hose connects the wheel cylinder/caliper to the brake line. Over time, these hoses can crack, develop pinholes, or become internally deteriorated, leading to leaks. This is more likely if the leak is near the hose connection point, rather than directly from the wheel cylinder itself.
* Caliper (if equipped with disc brakes): If your Grand Marquis has rear disc brakes (less common on that year, but possible depending on the trim level), a leaking caliper piston seal is a likely culprit. Similar to a wheel cylinder, a worn seal allows fluid to escape.
* Brake Line: While less common, a damaged or rusted brake line can also leak. This is more likely to cause a leak somewhere along the line's length, rather than specifically at the wheel.
What to Do:
1. Safety First: Low brake fluid levels are extremely dangerous. Do *not* drive the car until the leak is repaired. A complete brake failure could occur.
2. Locate the Exact Source: Carefully inspect the area around the wheel cylinder/caliper and brake hose for the leak. Look for wet spots, dripping fluid, or fluid trails.
3. Professional Repair: Brakes are critical safety components. Unless you have significant experience working on brakes, it's highly recommended to take the car to a qualified mechanic for diagnosis and repair. They have the tools and expertise to properly diagnose and fix the problem. Attempting a brake repair yourself could be very dangerous if done incorrectly.
Ignoring a brake fluid leak is extremely risky. Get it fixed immediately.
