If you're having brake problems, assuming the master cylinder is fine (no leaks, no damage), the issue likely lies in:
* Air in the brake lines: This is the most common cause of a soft brake pedal. You need to bleed the brakes at each wheel, starting with the furthest wheel from the master cylinder (usually the rear passenger side, then rear driver's side, then front passenger side, then front driver's side).
* Worn brake pads or shoes: Low brake pads will reduce stopping power and feel spongy.
* Low brake fluid: Check the master cylinder reservoir. Low fluid indicates a leak somewhere in the system.
* Master cylinder failure: This is less likely if you only have a soft pedal, but it's possible. Symptoms might include a spongy pedal that doesn't firm up, or a pedal that goes straight to the floor.
How to bleed the brakes (NOT the master cylinder directly):
You'll need a helper for this process. Here's a general procedure; refer to your Honda Prelude's service manual for precise locations and specifications:
1. Locate the bleed valves: These are typically on the top of each caliper.
2. Gather your materials: You'll need a wrench (size will depend on your car), clear tubing, a container to catch the fluid, and a helper. Also, have fresh DOT 3 brake fluid ready.
3. Check brake fluid level: Ensure the master cylinder reservoir is topped off with fresh DOT 3 brake fluid. Keep an eye on it and add more as needed during the bleeding process.
4. Open the bleed valve: Your helper will pump the brake pedal slowly and firmly several times. While the pedal is held down, open the bleed valve slightly using the wrench. Close the valve before your helper releases the brake pedal. Repeat this process several times until you see no more air bubbles coming through the tubing.
5. Repeat for each wheel: Follow the recommended sequence (rear passenger, rear driver, front passenger, front driver).
6. Check brake pedal: After bleeding all four wheels, have your helper pump the brake pedal. It should be firm and consistent. If not, repeat the bleeding process. If the problem persists, you likely have a more serious issue requiring professional attention.
7. Top off brake fluid: Make sure the brake fluid reservoir is filled to the correct level.
If you suspect a master cylinder problem: Do not attempt to bleed it yourself. A faulty master cylinder requires professional diagnosis and replacement. Trying to fix it yourself could be dangerous.
Always consult your Honda Prelude's repair manual for specific instructions and torque specifications. This procedure is a general guideline and may vary slightly based on your specific model year.
