Here's how to do it, emphasizing the importance of the proportioning valve:
Tools You'll Need:
* Brake bleeding kit: This usually includes a clear hose, a container to collect the fluid, and a wrench that fits your bleeder valves.
* New brake fluid: Use DOT 3 or DOT 4 brake fluid, as specified in your owner's manual. Never mix different types of brake fluid.
* Wrench: A 8mm or 10mm wrench (check your bleeder valve size).
* Helper: Having someone pump the brake pedal is significantly easier than doing it solo.
* Gloves: Brake fluid is corrosive.
* Clean rags: To wipe up spills.
Procedure:
1. Safety First: Engage the parking brake firmly. Work in a well-ventilated area, as brake fluid fumes are toxic.
2. Locate the Bleeder Valves: These are usually located on the top of each rear brake caliper.
3. Find and possibly deal with the Proportioning Valve: The proportioning valve is typically located near the rear of the vehicle, often close to the master cylinder or near the firewall. It might have a small adjusting screw or may simply be a valve block. You may NOT need to mess with this valve, but if you're experiencing uneven braking, you might need a professional mechanic's help here as incorrect adjustment can cause serious problems. Consult a repair manual specific to your 1990 Lincoln Mark VII for its location and whether adjustment is needed.
4. Open the Bleeder Valve: Attach the clear hose from your bleeding kit to the bleeder valve of the right rear wheel first (most diagrams show bleeding in a diagonal sequence, right rear, left front, left rear, right front but check your manual). Place the other end of the hose into your container.
5. Pump the Brakes: Have your helper firmly pump the brake pedal several times, then hold it down.
6. Open the Bleeder Valve: While your helper holds the pedal down, carefully open the bleeder valve with your wrench, allowing old brake fluid to flow into the container. Keep a close eye on the level in the master cylinder reservoir and add more fluid if necessary. Close the valve once the flow slows or stops.
7. Repeat: Repeat steps 5 and 6 several times until the fluid runs clean and free of air bubbles.
8. Repeat for other wheels: Follow the same procedure for the left rear wheel, then front wheels (right front and then left front).
9. Check for Leaks: After bleeding all four wheels, inspect for any leaks around the calipers, wheel cylinders, and brake lines.
10. Check Brake Pedal: Test the brake pedal; it should be firm and responsive. If it remains spongy, you may have air trapped in the system, a faulty master cylinder, or another problem requiring professional attention. You may need to repeat the bleeding process.
Important Considerations:
* Consult a Repair Manual: A repair manual specific to your 1990 Lincoln Mark VII is highly recommended. It will show you the exact location of the bleeder valves and the proportioning valve, and will provide specific instructions for your model.
* Professional Help: If you're uncomfortable performing this procedure yourself, or if you have persistent brake problems after bleeding, take your vehicle to a qualified mechanic. Brakes are critical safety components.
Failing to bleed the brakes correctly can lead to brake failure, so if you are not comfortable with this procedure, take your vehicle to a qualified mechanic.
