Brake System - General Information: Other Mercury Sable V

Material

Material

Hydraulic Brake System

Applying the brake pedal uses lever action to push a rod into the brake booster, which through the use of vacuum, boosts the force of the rod and then transmits this force into the master cylinder. This produces hydraulic pressure in the master cylinder. On vehicles not equipped with ABS, the hydraulic pressure is transmitted by brake fluid through the brake tubes to the individual brake calipers. On vehicles equipped with ABS, the hydraulic pressure is transmitted by brake fluid through the brake tubes to the ABS hydraulic control unit (HCU), which then distributes that pressure to the individual brake calipers. The brake calipers use hydraulic pressure to apply the pads. The application of the brake pads will cause the rotation of the wheels to slow or stop depending on how much brake pressure is applied. The parking brakes carry out the same function except that they are mechanically actuated by a cable that connects only to the rear brakes.

Red Brake Warning Indicator

The red brake warning indicator alerts the driver to certain conditions that exist in the brake system. The instrument cluster performs a bulb check when the ignition key is turned to the RUN position. The conditions that cause the indicator to illuminate are low brake fluid level, the parking brake is applied or there is a fault in the ABS (if the yellow ABS warning indicator is also illuminated).

Adjustable Pedals

The brake and accelerator pedals can be adjusted for a more comfortable driving position. The adjustable pedals feature is operational with the ignition switch in the RUN, ACC or OFF position. Adjustable pedals may be connected to the driver memory system, if equipped, or they may be a stand alone system.

Non-Memory Adjustable Pedals

For non-memory adjustable pedals, the pedals are controlled directly by the adjustable pedal switch and motor. The motor is attached to the accelerator pedal and the brake pedal is connected to the motor via a cable. The motor is connected to the brake pedal and accelerator pedal and both move together as an assembly. The pedals are adjusted by pressing the adjustable pedal switch in either the forward or rearward position. Pressing the switch powers the adjustable pedal motor which then causes the pedals to move either toward the driver or away from the driver.

Memory Adjustable Pedals

For memory adjustable pedals, the pedals can be adjusted in 1 of 3 ways

1. By pressing the adjustable pedal switch.
2. By pressing the memory position 1 or memory position 2 switch.
3. By using the remote transmitter.

For memory adjustable pedals, the pedals are controlled by the driver seat module (DSM). The DSM receives input from 1 of the 3 sources and then powers the adjustable pedal motor in the desired direction. The DSM will also control the driver seat position and the side-view mirror positions.

For information on the DSM and Memory Position Programming, refer to SEATING article.

Brake Pads

Note. It is not required to install new brake pads if friction material properties are within specifications. It is also not required to install new brake pads when the brake discs are machined.

1. Remove the brake pads. Refer to «FRONT DISC BRAKE»(ref-293510) article for front disc brakes or «REAR DISC BRAKE»(ref-293511) article for rear disc brakes.
2. Inspect and measure the thickness of the brake pad friction material. Refer to «SPECIFICATIONS»(ref-293454-S41726015232008080700000) . If there are missing chunks or cracks in the lining through to the backing plate, install new brake pads. Refer to «FRONT DISC BRAKE»(ref-293510) article for front disc brakes or «REAR DISC BRAKE»(ref-293511) article for rear disc brakes. If the thickness of the friction material is less than the specified thickness, install new brake pads. Refer to «FRONT DISC BRAKE»(ref-293510) article for front disc brakes or «REAR DISC BRAKE»(ref-293511) article for rear disc brakes. If the friction material shows taper wear that is not within specifications, verify the caliper guide pins are functioning correctly. Refer to «Brake Caliper Guide Pins»(ref-293454-S29836588212008080700000) .

Brake Discs

Note. Using an impact tool without a torque socket will lead to unevenly tightened lug nuts. This causes brake disc on-vehicle lateral runout and brake roughness.

Note. It is generally not required to install new brake discs to address noise issues.

1. Remove the brake disc. Refer to «FRONT DISC BRAKE»(ref-293510) article for front disc brakes or «REAR DISC BRAKE»(ref-293511) article for rear disc brakes.
2. Inspect the brake discs and measure the brake disc thickness in a minimum of 4 places around the circumference of the brake disc. Record the measurements, refer to «SPECIFICATIONS»(ref-293454-S41726015232008080700000) . If the brake disc is cracked or otherwise damaged, install new a brake disc. Refer to «FRONT DISC BRAKE»(ref-293510) article for front disc brakes or «REAR DISC BRAKE»(ref-293511) article for rear disc brakes. If any thickness measurement is less than the minimum specification, install a new brake disc. Refer to «FRONT DISC BRAKE»(ref-293510) article for front disc brakes or «REAR DISC BRAKE»(ref-293511) article for rear disc brakes. If the diagnosis has revealed vibration in the steering wheel, seat or pedal while braking that varies with vehicle speed, machine the brake disc. Heavily scored brake discs, similar to that caused by pads worn down to the backing plate, should also be machined. In order to machine, discs must be above the minimum thickness specification. Refer to Specifications and «Brake Disc Machining»(ref-293454-S14760388102008080700000) .

Brake Calipers

Inspect the brake calipers for the following

1. Brake fluid leaks. Refer to «Brake System Leak Check»(ref-293454-S02140026732008080700000) and «Non-Pressure Leaks»(ref-293454-S29796773932008080700000) .
2. Boots and seals for tears or cracks.
3. Caliper pistons for binding and corrosion.
4. Guide pins for correct operation. Refer to «Brake Caliper Guide Pins»(ref-293454-S29836588212008080700000) .

Brake Caliper Guide Pins

Note. Do not use power tools for caliper guide pin bore cleaning. Damage to the bore may result.

Note. The guide pins are part of the anchor plate.

The guide pins should slide with a reasonable amount of hand force. If the brake pads show taper wear or the guide pins are difficult to move, install a new brake caliper anchor plate. Refer to FRONT DISC BRAKE article for the front brake caliper anchor plate or REAR DISC BRAKE article for the rear brake caliper anchor plate.

If the lining is not within specifications, install new brake pads. Refer to FRONT DISC BRAKE article for front disc brakes or REAR DISC BRAKE article for rear disc brakes.

Brake Hoses and Tubes

Note. Never use copper tubing. It is subject to fatigue, cracking and corrosion, which may result in brake tube failure.

1. Double-wall steel tubing is used throughout the brake hydraulic system. All brake tube fittings must be correctly double flared to provide strong, leakproof connections. When bending tubing to fit the underbody or rear axle contours, be careful not to kink or crack the tube.
2. If a section of the brake tube is damaged, the entire section must be installed with a new tube of the same type, size, shape and length.
3. When installing the hydraulic brake tubing, hoses or connectors, tighten all connections to specifications. After installation, bleed the brake system. Refer to «Brake System Bleeding»(ref-293454-S13318392262008080700000) .

Install a new brake flexible hose if the hose shows signs of softening, cracking or other damage.

When installing a new brake hose, position the hose to avoid contact with other vehicle components.

Non-Pressure Leaks

Two parts of the brake system that may have a brake fluid loss that does not appear when the system is under pressure are the brake master cylinder reservoir and the brake caliper under the following conditions

Reservoir

1. Missing or poorly-fitted brake master cylinder filler cap
2. Missing or damaged brake master cylinder filler cap gasket
3. Punctured or otherwise damaged brake master cylinder reservoir
4. Missing, damaged or poorly-fitted sealing grommets between the brake master cylinder and the brake master cylinder reservoir

The brake master cylinder reservoir grommets are not serviceable and must be installed new as part of a new reservoir assembly. Refer to Brake Fluid Reservoir in HYDRAULIC BRAKE ACTUATION article.

Caliper

1. Foreign material in the caliper piston seal groove
2. Punctured or otherwise damaged caliper piston seal

The brake caliper piston seals are not serviceable and must be installed new as part of a new brake caliper. Refer to FRONT DISC BRAKE article for front disc brakes or REAR DISC BRAKE article for rear disc brakes.

Brake Master Cylinder - Normal Conditions

The following conditions are considered normal and are not indications that the brake master cylinder is in need of service.

Condition 1: During normal operation of the brake master cylinder, the fluid level in the brake master cylinder reservoir will fall during brake application and rise during release. The net fluid level (such as after brake application and release) will remain unchanged.

Condition 2: A trace of brake fluid will exist on the booster shell below the master cylinder mounting flange. This results from the normal lubricating action of the master cylinder bore and seal.

Condition 3: Fluid level will decrease with pad wear.

Brake Master Cylinder - Abnormal Conditions

Changes in brake pedal feel or travel are indicators that something may be wrong in the brake system. Go to Symptom Chart - Hydraulic Brake System for abnormal condition diagnosis.

Brake Booster

Inspect the brake booster

1. for excessive corrosion or damage.
2. vacuum connections for leakage.
3. vacuum hoses for kinks or leakage.
4. check valve for correct operation.

Parking Brake

Check the operation of the parking brake system with the vehicle on a hoist and the parking brake control fully released. Check for any damaged cables and install new components as necessary. Check the rear brake adjustment or carry out the brake system diagnosis. Refer to PARKING BRAKE AND ACTUATION article.

1. Disconnect the check valve from the brake booster.
2. Apply the parking brake, start the engine and place the transmission in NEUTRAL.
3. Verify that manifold vacuum is available at the check valve with the engine at idle speed and the transmission in NEUTRAL. If manifold vacuum is available, stop the engine, connect the check valve and continue with Step 5. If manifold vacuum is not available, continue with Step 4.
4. Disconnect the check valve from the vacuum hose and verify that manifold vacuum is available at the hose with the engine at idle speed and the transmission in NEUTRAL. If manifold vacuum is available, stop the engine, install a new check valve and continue with Step 5. If manifold vacuum is not available, stop the engine, connect the vacuum hose to the check valve and refer to «ENGINE SYSTEM - GENERAL INFORMATION»(ref-293455) article to diagnose the no vacuum condition.
5. Apply the brake pedal several times to exhaust all vacuum from the system.
6. Apply the brake pedal and hold it in the applied position. Start the engine and verify that the brake pedal moves downward after the engine starts. If the brake pedal moves, the brake booster is operating correctly If the brake pedal does not move, install a new brake booster. Refer to «POWER BRAKE ACTUATION»(ref-293516) article.
7. Operate the engine a minimum of 10 seconds at fast idle. Stop the engine, and let the vehicle stand for 10 minutes. Then apply the brake pedal with approximately 89 N (20 lb) of force. The brake pedal feel should be the same as that noted with the engine operating. If the brake pedal feels hard (no power assist), install a new brake booster check valve and retest. If the brake pedal feels spongy, bleed the hydraulic system to remove air. Refer to «Brake System Bleeding»(ref-293454-S13318392262008080700000) .

Check Valve

The function of the brake booster check valve is to allow manifold vacuum to enter the brake booster and prevent the escape of vacuum in case manifold vacuum is lost during sustained full throttle operation.

1. Disconnect the vacuum booster hose from the check valve.
2. Apply the parking brake, start the engine and place the transmission in NEUTRAL.
3. Verify that manifold vacuum is available at the check valve end of the vacuum hose with the engine at idle speed and the transmission in NEUTRAL. If manifold vacuum is available, stop the engine, connect the vacuum hose to the check valve and continue this test. If manifold vacuum is not available, stop the engine, connect the vacuum hose to the check valve and refer to «ENGINE SYSTEM - GENERAL INFORMATION»(ref-293455) article to diagnose the no vacuum condition.
4. Connect the vacuum hose to the check valve and run the engine for at least 10 seconds.
5. Operate the brake pedal to check for power assist. If power assist is present, continue with this test. If power assist is not present, refer to «Brake Booster»(ref-293454-S10949345122008080700000) Component Test.
6. Stop the engine and disconnect the vacuum booster hose from the brake booster check valve.
7. Apply the brake and verify that there is enough vacuum retained in the brake booster for at least one power-assisted brake application. If there is enough vacuum for at least one power-asssisted brake application, the check valve is functioning correctly. If there is not enough vacuum for at least on one power-asssisted brake application, continue with this test.
8. Inspect the brake booster for any signs of damage that may cause a leak. If any damage is found, install a new brake booster and repeat this test. If no damage is found, install a new check valve.

Brake Master Cylinder - Bypass Condition

1. Disconnect the brake tubes from the master cylinder.
2. Plug the outlet ports of the master cylinder.
3. Apply the brakes. If brake pedal height cannot be maintained, the brake master cylinder has an internal leak and a new brake master cylinder must be installed.

Brake Master Cylinder - Compensator Port

The purpose of the compensator ports in the brake master cylinder is to

1. supply additional brake fluid from the brake master cylinder reservoir needed by the brake system due to brake lining wear.
2. allow brake fluid to return to the brake master cylinder reservoir when the brakes are released. The returning brake fluid creates a slight turbulence in the brake master cylinder reservoir. This is a normal condition and indicates that the compensator ports are not clogged.

Clogged compensator ports may cause the brakes to hang up or not fully release. If clogged compensator ports are suspected, proceed as follows

1. With the vehicle in NEUTRAL, position it on a hoist. Refer to «JACKING AND LIFTING»(ref-293448) article.
2. With the brakes released, attempt to rotate each wheel and check for any brake drag. If an excessive amount of brake drag exists at all 4 wheels, continue with the test. If an excessive amount of brake drag exists at only one wheel, it indicates a possible seized brake caliper, brake wheel cylinder or parking brake component. Repair or install new components as necessary.
3. Check the brake stoplamp switch and the brake pedal free play to verify that the brake pedal is not partially applied.
4. Loosen the brake master cylinder nuts and position the brake master cylinder away from the brake booster.
5. With the brakes released, attempt to rotate each wheel and check for any brake drag. If the brake drag is no longer present, install a new brake booster. Refer to «POWER BRAKE ACTUATION»(ref-293516) article. If the brake drag is still present, install a new master cylinder. Refer to «HYDRAULIC BRAKE ACTUATION»(ref-293515) article.

Brake Disc Machining

Note. Do not use a bench lathe to machine the brake discs. Use an on-vehicle brake lathe only. Read the entire operating manual and/or view the video shipped with the lathe before installing, operating or repairing the lathe.

Note. An on-vehicle brake lathe with an automatic runout adjustment feature is preferred. However, if the lathe is not self adjusting, the lathe oscillation must be adjusted using a dial indicator. The total indicated runout target is 0.000 mm (0.000 in). The maximum indicated runout should be no more than 0.050 mm (0.002 in). If the runout adjustment (automatic or manual) is carried out correctly prior to machining, then the final brake disc runout will be within specification and a runout measurement is not necessary after machining.

Note. Do not machine new brake discs.

Note. Lateral runout and disc thickness variation measurements are not required because correct adjustment of the on-vehicle brake lathe will make sure that these dimensions are within specification.

1. Remove the wheel and tire. For additional information, refer to «WHEELS AND TIRES»(ref-293452) article.
2. Remove the bolts and position the brake caliper or brake caliper and anchor plate assembly aside, as required. Support the brake caliper using mechanic's wire.
3. Install the hub adapter using: four wheel nuts on a 4-stud wheel hub. five wheel nuts on a 5-stud wheel hub. six wheel nuts on a 6-stud wheel hub. four wheel nuts on a 7- or 8-stud wheel hub. five wheel nuts on a 10-stud wheel hub.
4. Install the cutting lathe.
5. If the lathe is not self adjusting, adjust the lathe oscillation using a dial indicator. The total indicated runout target is 0.000 mm (0.000 in). The maximum indicated runout should be no more than 0.050 mm (0.002 in).
6. Center the cutting head, adjust the cutting bits and install the chip deflector/silencer.
7. Machine the brake disc.
8. Remove the lathe and the silencer.
9. Remove the wheel nuts and hub adapter.
10. Remove the metal shavings.
11. Position the brake caliper or brake caliper and anchor plate assembly. Install the bolts. For fastener torque specifications, refer to «FRONT DISC BRAKE»(ref-293510) article for front disc brakes or «REAR DISC BRAKE»(ref-293511) article for rear disc brakes.
12. Install the wheel and tire. For additional information, refer to «WHEELS AND TIRES»(ref-293452) article.

Component Bleeding

Material

Master Cylinder

Note. Brake fluid is harmful to painted and plastic surfaces. If brake fluid is spilled onto a painted or plastic surface, immediately wash it with water.

Note. When any part of the hydraulic system has been disconnected for repair or installation of new components, air can enter the system and cause spongy brake pedal action. This requires bleeding of the hydraulic system after it has been correctly connected. The hydraulic system can be bled manually or with pressure bleeding equipment.

Note. When a new brake master cylinder has been installed or the system has been emptied, or partially emptied, it should be primed to prevent air from entering the system.

1. Disconnect the brake tubes from the master cylinder.
2. Install short brake tubes onto the primary and secondary ports with the ends submerged in the brake master cylinder reservoir.
3. Fill the brake master cylinder reservoir with clean, specified brake fluid.
4. Have an assistant pump the brake pedal until clear fluid flows from the brake tubes without air bubbles.
5. Remove the short brake tubes, and install the master cylinder brake tubes. Tighten to 18 Nm (13 lb-ft).
6. Bleed each brake tube at the brake master cylinder as follows: Have an assistant pump the brake pedal, and then hold firm pressure on the brake pedal. Loosen the rear-most brake tube fittings until a stream of brake fluid comes out. While the assistant maintains pressure on the brake pedal, tighten the brake tube fitting. Repeat this operation until clear, bubble-free fluid comes out. Refill the brake master cylinder reservoir as necessary. Repeat the bleeding operation at the front brake tube.

Brake Caliper

Note. Brake fluid is harmful to painted and plastic surfaces. If spilled, wipe up immediately before damage to the painted or plastic surface occurs.

1. Remove the brake caliper bleeder screw cap and place a box end wrench on the bleeder screw. Attach a rubber drain hose to the bleeder screw and submerge the free end of the hose in a container partially filled with clean, specified brake fluid.
2. Have an assistant pump the brake pedal and then hold firm pressure on the brake pedal.
3. Loosen the bleeder screw until a stream of brake fluid comes out. While the assistant maintains pressure on the brake pedal, tighten the bleeder screw. Repeat until clear, bubble-free fluid comes out. Refill the brake master cylinder reservoir as necessary.
4. Tighten the brake caliper bleeder screw, remove the rubber hose and install the bleeder screw cap. Tighten the front brake caliper bleeder screws to 12 Nm (9 lb-ft). Tighten the rear brake caliper bleeder screws to 10 Nm (89 lb-in).

Brake System Bleeding

Special Tools Illustration Tool Name Tool Number Vehicle Communication Module (VCM) and Integrated Diagnostic System (IDS) software with appropriate hardware, or equivalent scan tool

Material

Pressure

Note. Brake fluid is harmful to painted and plastic surfaces. If brake fluid is spilled onto a painted or plastic surface, immediately wash it with water.

Note. Pressure bleeding the brake system at 207-345 kPa (30-50 psi) is preferred to manual bleeding.

Note. When any part of the hydraulic system has been disconnected for repair or installation of new components, air can get into the system and cause spongy brake pedal action. This requires bleeding of the hydraulic system after it has been correctly connected.

Note. If the hydraulic control unit (HCU) or any component upstream of the HCU are installed new, carry out the brake system bleed procedure first without the scan tool, followed by the brake system bleed procedure using the scan tool.

Note. Pressure bleed the brake system at 207-345 kPa (30-50 psi).

Note. Due to the complexity of the fluid path within the rear integral parking brake calipers, it is necessary to press and release the parking brake during the bleed procedure.

1. Clean all the dirt from around the brake fluid reservoir cap and remove the cap. Fill the brake master cylinder reservoir with clean, specified brake fluid.
2. Install the bleeder adapter to the brake master cylinder reservoir and attach the bleeder tank hose to the fitting on the adapter.
3. Remove the RH rear bleeder cap and place a box-end wrench on the bleeder screw. Attach a rubber drain tube to the RH rear bleeder screw and submerge the free end of the tube in a container partially filled with clean, specified brake fluid.
4. Open the valve on the bleeder tank.
5. Loosen the RH rear bleeder screw. Leave open until clear, bubble-free brake fluid flows, then tighten the RH rear bleeder screw. Press and release the parking brake 5 times. Repeat until clear, bubble-free fluid comes out.
6. Tighten the RH rear bleeder screw to 10 Nm (89 lb-in), remove the rubber hose and install the bleeder screw cap.
7. Repeat Steps 5 and 6 for the LH rear brake caliper.
8. Continue bleeding the front of the system, going in order from the RH front brake caliper and then to the LH front brake caliper. Tighten the front brake caliper bleeder screws to 12 Nm (9 lb-ft).
9. Close the bleeder tank valve. Remove the tank hose from the adapter and remove the adapter. Fill the reservoir with clean, specified brake fluid and install the reservoir cap.

Manual

Note. Brake fluid is harmful to painted and plastic surfaces. If brake fluid is spilled onto a painted or plastic surface, immediately wash it with water.

Note. When any part of the hydraulic system has been disconnected for repair or installation of new components, air can get into the system and cause spongy brake pedal action. This requires bleeding of the hydraulic system, including the hydraulic control unit (HCU) after it has been correctly connected.

Note. If the HCU or any component upstream of the HCU are installed new, carry out the brake system bleed procedure first without the scan tool, followed by the brake system bleed procedure using the scan tool.

Note. Due to the complexity of the fluid path within the rear integral parking brake calipers, it is necessary to press and release the parking brake during the bleed procedure.

1. Clean all the dirt from around the brake fluid reservoir cap and remove the cap. Fill the brake master cylinder reservoir with clean, specified brake fluid.
2. Remove the RH rear bleeder cap and place a box-end wrench on the bleeder screw. Attach a rubber drain tube to the RH rear bleeder screw and submerge the free end of the tube in a container partially filled with clean, specified brake fluid.
3. Have an assistant hold firm pressure on the brake pedal.
4. Loosen the RH rear bleeder screw until a stream of brake fluid comes out. While the assistant maintains pressure on the brake pedal, tighten the RH rear bleeder screw. Press and release the parking brake 5 times. Repeat until clear, bubble-free fluid comes out. Refill the brake master cylinder reservoir as necessary.
5. Tighten the RH rear bleeder screw to 10 Nm (89 lb-in), remove the rubber hose and install the bleeder screw cap.
6. Repeat Steps 2 through 5 for the LH rear brake caliper.
7. Remove the RH front bleeder cap and place a box-end wrench on the bleeder screw. Attach a rubber drain tube to the RH front bleeder screw and submerge the free end of the tube in a container partially filled with clean, specified brake fluid.
8. Have an assistant hold firm pressure on the brake pedal.
9. Loosen the RH front bleeder screw until a stream of brake fluid comes out. While the assistant maintains pressure on the brake pedal, tighten the RH front bleeder screw. Repeat until clear, bubble-free fluid comes out. Refill the brake master cylinder reservoir as necessary.
10. Tighten the RH front bleeder screw to 12 Nm (9 lb-ft), remove the rubber hose and install the bleeder screw cap.
11. Repeat Steps 7 through 10 for the LH front brake caliper bleeder screw.

ABS Hydraulic Control Unit (HCU) Bleeding

Note. When any part of the hydraulic system has been disconnected for repair or installation of new components, air can get into the system and cause spongy brake pedal action. This requires bleeding of the hydraulic system, including the hydraulic control unit (HCU) after it has been correctly connected.

Note. If the HCU or any component upstream of the HCU are installed new, carry out the brake system bleed procedure first without the scan tool, followed by the brake system bleed procedure using the scan tool.

Note. This procedure is only required when a new hydraulic control unit is installed.

1. Connect the scan tool and follow the ABS HCU bleed instructions.
2. Follow the pressure bleeding or manual bleeding procedure steps to bleed the system.

Brake System Leak Check

1. Make sure the brake master cylinder reservoir is full.
2. Apply the brakes several times and make sure the brake pedal feel is not spongy. If necessary, bleed the system. For additional information, refer to «Brake System Bleeding»(ref-293454-S13318392262008080700000) .
3. Hold pressure on the brake pedal for 30 seconds.
4. Verify that the reservoir level is not dropping.
5. If the reservoir level is dropping, inspect the brake components, fittings, hoses and tubes to locate the source of the leak.