1. Low Brake Fluid: This is the simplest and most common cause. Check your brake fluid reservoir (usually a clear plastic container near the master cylinder under the hood). If it's low, you have a leak somewhere in the system. Do not just add fluid! Find and fix the leak first, otherwise you'll just keep losing fluid.
2. Air in the Brake Lines (Air in the System): Air in the brake lines will make the pedal feel spongy or hard. This often happens after brake work or a brake fluid leak. Bleeding the brakes is necessary to remove the air. You'll need a wrench, a clear tube, and a helper to do this correctly. There are many online tutorials on bleeding brakes – be sure to follow the correct order for your specific Blazer model.
3. Master Cylinder Issues: The master cylinder is the pump that converts pedal pressure into hydraulic pressure to the brakes. A failing master cylinder can cause a hard pedal, often accompanied by a loss of braking power. This requires replacement.
4. Vacuum Booster Problems: The vacuum booster assists the master cylinder by using engine vacuum to reduce the effort needed to press the brake pedal. A failing booster will result in a very hard pedal, especially noticeable at idle. You'll need to check for vacuum leaks in the lines and the booster itself, a replacement is often required.
5. Power Brake System Problems: Issues with the power brake system components might cause a hard pedal. This could range from leaks to faulty components within the system itself.
6. Restricted Brake Caliper(s) or Wheel Cylinders: If a caliper piston is seized or a wheel cylinder is failing, it will make the pedal harder. This restricts brake fluid flow.
7. ABS System Issues (Less Likely, but Possible): While less likely to cause a completely hard pedal, problems with the Anti-lock Braking System (ABS) could contribute to a firmer-than-normal pedal feel. Diagnosis of ABS issues requires specialized tools.
Troubleshooting Steps:
1. Check brake fluid level: This is the first and easiest thing to do.
2. Check for leaks: Inspect brake lines, calipers, wheel cylinders, and the master cylinder for any signs of leaks (wet spots, dripping fluid).
3. Feel the brake pedal: Is it hard all the time, or only after the vehicle has been driven for some time? This will help pinpoint the issue.
4. Listen for unusual noises: While braking, listen for squealing, grinding, or other unusual noises that might indicate a problem with the brakes.
5. Try to bleed the brakes: If you suspect air in the lines.
6. If unsure, take it to a mechanic: Brake issues are serious. If you're not comfortable working on your brakes yourself, take your Blazer to a qualified mechanic for diagnosis and repair. Improper brake repair can be dangerous.
Safety Note: Driving with a hard brake pedal is unsafe. It indicates a problem with your braking system and should be addressed immediately. Avoid driving the vehicle until the issue is resolved.
