1. Vacuum Leaks: This is the most common culprit. The power brake booster relies on engine vacuum to assist braking. Leaks can occur in several places:
* Booster itself: A cracked or damaged diaphragm inside the booster is a frequent problem. This often manifests as a hissing sound near the booster when the brakes are applied.
* Vacuum hoses: Check all vacuum hoses connected to the booster. Look for cracks, holes, or loose connections. These hoses are usually made of rubber and can deteriorate over time.
* Intake manifold gasket: A leak in the intake manifold gasket can reduce engine vacuum, affecting the booster.
* Vacuum pump (if equipped): Some vehicles have a vacuum pump to supplement engine vacuum. A faulty pump could be the problem. The '95 SC1 likely doesn't have one, but it's worth considering if other vacuum sources are ruled out.
2. Brake Master Cylinder: A failing master cylinder can also lead to loss of power assist. This is less common than a vacuum leak but should be checked. Symptoms might include:
* Spongy brake pedal: A soft or mushy pedal feel indicates a problem with the master cylinder.
* Low brake fluid: Check the brake fluid reservoir. Low fluid could indicate a leak in the system. Never top off brake fluid without identifying the leak first.
* Fluid leaks: Inspect the master cylinder for leaks around its seals.
3. Brake Booster Check Valve: This small valve prevents brake fluid from flowing back into the vacuum lines. A faulty check valve can cause loss of vacuum assist.
4. Less Likely but Possible:
* Faulty Brake Lines or Hoses: While unlikely to cause a *sudden* complete loss of power brakes, leaks in the brake lines or hoses can eventually lead to air in the system, affecting brake performance.
* Low Brake Fluid: A low brake fluid level can severely compromise braking performance. This is important to rule out.
Troubleshooting Steps:
1. Check Brake Fluid Level: This is the first and most important step. Low fluid indicates a leak somewhere in the system.
2. Listen for Hissing: With the engine running, listen carefully around the brake booster for hissing sounds, indicating a vacuum leak.
3. Inspect Vacuum Hoses: Visually inspect all vacuum hoses connected to the booster for cracks, holes, or loose connections.
4. Check for Leaks at the Master Cylinder: Inspect the master cylinder for any signs of leakage.
5. Test the Brake Booster: This requires a vacuum gauge and some mechanical knowledge. A low vacuum reading indicates a leak. (This is best left to a mechanic unless you're experienced.)
6. Test the Brake Pedal: With the engine off, pump the brake pedal several times. If the pedal gets harder with each pump, the problem is likely a vacuum leak.
If you're not comfortable performing these checks yourself, take your vehicle to a qualified mechanic immediately. Driving with compromised brakes is extremely dangerous. The safety of yourself and others is paramount. Don't attempt repairs if you lack the experience.
