1. Re-bleeding, but do it right:
* Proper Procedure: Ensure you're bleeding the brakes correctly. The order is crucial: farthest wheel from the master cylinder first (usually a rear wheel), then the other rear, then the front wheels (closest to the master cylinder last). This helps push air towards the exit point. Have someone pump the brake pedal firmly and steadily while you open and close the bleeder valve.
* Vacuum Bleeder: A vacuum bleeder is far more effective than just pumping the pedal. It creates consistent suction, pulling air out more efficiently. This is highly recommended if you've already tried manual bleeding.
* Pressure Bleeder: Even better than a vacuum bleeder is a pressure bleeder, which pressurizes the master cylinder, forcing air out from all calipers simultaneously.
2. Inspect for Leaks:
* Master Cylinder: Check the master cylinder for leaks. Look for wetness or fluid dripping around the cylinder itself. A leaking master cylinder needs to be replaced.
* Brake Lines and Hoses: Carefully inspect all brake lines and hoses for cracks, kinks, or damage. Even a tiny hole can introduce air into the system. Pay close attention to the connections at the calipers and the wheel cylinders.
* Wheel Cylinders (Rear Drums): If your Astro has rear drum brakes, the wheel cylinders themselves might be leaking internally. This often requires replacing the wheel cylinders.
* Caliper Seals (Front Discs): On the front disc brakes, the caliper seals could be leaking internally, allowing air to enter.
3. Check the Brake Booster:
* Vacuum Leak: The brake booster uses engine vacuum to assist braking. A leak in the booster's vacuum line or a faulty booster itself can significantly reduce brake pressure or even cause a complete failure. Listen for hissing sounds near the booster. You can test the booster's vacuum by using a vacuum gauge.
* Booster Diaphragm: The booster diaphragm could be ruptured.
4. ABS System (If Equipped):
* ABS Module Issues: Some 1995 Astros might have ABS. A malfunctioning ABS module can interfere with braking, even if the conventional braking system is fine. You might need a diagnostic scan tool to check for ABS codes.
5. Master Cylinder Internal Problems:
* Internal Damage: Sometimes, the problem isn't a leak but damage *inside* the master cylinder, such as a piston seal failure, preventing it from building sufficient pressure.
6. Proportioning Valve (If Equipped):
* Blockage or Failure: Some vehicles have a proportioning valve that balances braking force between the front and rear wheels. A problem with this valve could prevent sufficient pressure from reaching one or more wheels.
If you've done all of the above and still have no pressure:
* Professional Help: At this point, it's best to take your Astro to a qualified mechanic. The problem is likely more serious than a simple air bubble, and a professional will have the tools and expertise to diagnose and fix it safely. Driving a vehicle with weak or failing brakes is extremely dangerous.
Important Safety Note: Do not attempt to drive your Astro van if it has weak or no brakes. This is incredibly dangerous and could lead to a serious accident. Have it towed to a repair shop.
