Brake Bleeding: Service and Repair

BLEEDING OF BRAKES

Normal mechanical bleeding is usually sufficient when reconditioning or replacing a brake caliper. In this case, the brake pedal must be depressed throughout the operation to ensure that the system is not drained of fluid. A bleeding unit must be used if the system has been drained either wholly or partially.

In other bleeding operations and when changing the fluid, a bleeding unit which pressurizes the system to 2-3 bar (29-44 lb/in2) must be used.

Use only genuine Volvo brake fluid with the designation DOT 4+. Never re-use drained fluid. Always store fluid in the original container, tightly sealed.

Note: ABS systems take longer to bleed than conventional systems.

A1

- Switch off ignition.

- Jack up and support car.

- Clean brake fluid reservoir and cap before removing cap.

A2





- Connect bleeding unit to brake fluid reservoir.

- Follow supplier's instructions regarding connection and operation of unit.

A3

- Operate brake pedal:
• Operate pedal several times to expel any air bubbles in master cylinder.

Note: This should be carried out between each bleeding operation on the particular caliper.

A4

- Bleed calipers in following order:
• Cars with ABS, models to 1987 inclusive:
- Bleed one front wheel, second front wheel and rear wheels in that order.
• Cars without ABS, and 1988 or later models with ABS:
- Bleed one rear wheel, second rear wheel and front wheels in that order.

A5

- Bleeding of front brake calipers:





• Illustration shows bleeding of single-piston caliper.
• Remove dust cap(s) from bleeding nipple(s).
• Connect fluid collector tube to nipple.
• Open nipple and close when air bubbles are no longer present in escaping fluid. Tighten nipple to 10 Nm (7.5 ft.lb).
• Cars with two-piston calipers:
- Connect tube to upper nipple and carry out above procedure.
• Refit dust cap(s) on bleeding nipples(s).
• Bleed other caliper as described above.

A6

- Bleeding of rear brake calipers:





• Picture illustrates bleeding of caliper for live rear axle.
• Remove dust cap from bleeding nipple.

Note: Upper bleeding nipple must be used on cars with multilink rear axles.

• Open nipple and close when air bubbles are no longer visible in escaping fluid. Tighten nipple to 4.5 Nm (3.3 ft lb).
• Refit dust cap on bleeding nipple.
• Bleed other caliper as described above.

A7

- Depressurize system:
• Check system. Check for air in system by operating brake pedal at force equivalent to hard braking.
• Disconnect bleeding unit from brake fluid reservoir.
• Check level in reservoir.
• Check that vent hole in reservoir cap is free of dirt. Fit cap.
• Wash off fluid spillage, if any, with lukewarm water and car shampoo.
• Lower car.