Removing air from the brake system is done by bleeding the brake pedal, which requires an assistant.
If the entire system needs to be bled, each wheel brake is bled separately. This occurs when air enters each individual brake cylinder.
Air removal sequence:
- 1. Rear left brake cylinder.
- 2. Front right brake cylinder.
- 3. Rear right brake caliper (or cylinder).
- 4. Front left brake caliper.
If only one caliper or wheel cylinder has been replaced or repaired, it is usually sufficient to bleed the corresponding brake cylinder.
Before removing air, unscrew the reservoir cap and add brake fluid up to the MAX mark.
Note: When bleeding air, occasionally look at the brake fluid reservoir. The fluid level should not drop too much, otherwise air will be sucked in through the reservoir. Top up with new brake fluid only!
Remove cap "1" from the brake cylinder air bleeder valve and fit a wrench. Clean the valve, connect a clean transparent hose, lower the other end of the hose into a bottle half filled with brake fluid (a suitable hose and corresponding container are available in auto parts stores). On an older car, spray the air bleeder valve with a rust remover aerosol and carefully ensure that the valve turns easily.
The container with brake fluid must be placed at least 30 cm above the air release valve, otherwise air will enter the system through the valve thread.
The assistant should press the brake pedal several times until pressure is created in the brake system. This will be felt by the increased resistance when pressing the pedal.
When the pressure is reached, keep the pedal pressed.
Open the brake caliper air release valve with a key by about half a turn. The brake fluid will flow into the container. Make sure that the end of the hose in the container is always inside the fluid.
As soon as the fluid pressure drops, immediately close the air release valve.
Repeat the inflation process until pressure is created. Keep your foot on the pedal. Open the air release valve until the pressure drops. Close the valve.
Continue the process of removing air from the brake cylinder until no more air bubbles are released from the fluid flowing into the bottle.
After removing the air, carefully tighten the valve with a force of approximately 10 Nm.
Remove the hose and put the cap on the valve.
In the same way, remove air from the cylinders of the remaining wheels, following the above sequence of actions.
After removing the air, the tank should be filled to the MAX mark and the tank should be closed with a lid.