* Air in the brake lines: This is the most common cause. Air is compressible, unlike brake fluid. When air gets into the system, the brake pedal feels spongy or goes all the way to the floor because the air compresses instead of transferring pressure effectively to the calipers or wheel cylinders. Air can enter due to:
* Low brake fluid: If the fluid level gets too low, air can be sucked in.
* Leaking brake lines or components: A leak anywhere in the system (hoses, calipers, wheel cylinders, master cylinder) can allow air to enter.
* Worn brake components: Severely worn brake pads or shoes can sometimes allow air to get past the seals.
* Improper bleeding procedure: If the brake system wasn't bled properly after a repair (like replacing a caliper or brake line), air will remain.
* Master cylinder failure: A failing master cylinder can allow air to be drawn into the system.
* Moisture in the brake fluid: Over time, moisture can absorb into the brake fluid. This can lead to corrosion and the formation of air bubbles. Brake fluid is hygroscopic which means it attracts moisture.
* Brake system work: Any work done on the brake system (replacing components, repairs to lines, etc.) almost always necessitates bleeding.
Troubleshooting:
To figure out *why* your 1998 Buick Regal's brakes are bleeding, you'll need to investigate:
1. Check the brake fluid level: Is it low? If so, you need to find the leak.
2. Inspect brake lines and hoses: Look for any signs of leaks, cracks, or damage.
3. Examine calipers and wheel cylinders (if applicable): Look for leaks around the seals.
4. Check the master cylinder: Look for leaks or signs of damage.
5. Feel the brake pedal: How does it feel? Spongy, soft, or hard? A spongy pedal strongly indicates air in the lines.
If you find a leak or other damage, you'll need to repair or replace the faulty component *before* bleeding the brakes. Bleeding the brakes won't fix a leak. If no leaks are found, it's likely you just need to bleed the brakes properly. This usually requires two people: one to pump the brake pedal and one to open and close the bleeder valves on each caliper. Consult your owner's manual or a repair manual for the proper bleeding procedure. If you're not comfortable working on your brakes, take it to a qualified mechanic.
