It is recommended to use a special installation for pumping the hydraulic drive under pressure. If not, you can bleed the brake drive by pressing the brake pedal. In this case, an assistant is needed. The efficiency of this method is lower, and labor costs are greater than when using a special installation.
Use only fresh brake fluid for bleeding. Before carrying out work, make sure that all brake drive units and their connections are tight, clean the cover and the surface around the compensation tank cover, thoroughly clean the bleeder fittings. Prepare a reliable tool for unscrewing the fittings - they can firmly «take a liking» to your place.
If only part of the system has been depressurized and all the precautions necessary to minimize fluid loss have been observed, it is sufficient to vent only the relevant circuit.
If the entire brake system was subjected to depressurization, the bleeding sequence is as follows.
On a vehicle without ABS:
- right rear wheel;
- left front wheel;
- left rear wheel;
- right front wheel.
On a vehicle with ABS:
- right rear wheel;
- left front wheel;
- left rear wheel;
- right front wheel.
During pumping, constantly monitor the level of brake fluid in the reservoir and maintain it at the mark «MAX».
Bleed the brakes in the following order:
- remove the dust cap from the first fitting in the order of bleeding on the brake wheel cylinder, put on it a hose to drain the brake fluid, lower the free end of which into a glass vessel partially filled with liquid;
- ask the assistant to sharply press the brake pedal several times until you feel «stop» and hold the pedal in this position;
- unscrew the fitting by 1/2–1/3 turn using the prepared key - liquid will enter the vessel from the hose along with air bubbles, and the pedal held by the assistant will rest on the floor;
- while the assistant keeps the pedal depressed, tighten the fitting; the end of the hose must be constantly immersed in the liquid;
- repeat this operation until liquid without air bubbles enters the vessel;
- periodically check the fluid level in the compensation tank, topping it up to the mark «MAX»;
- while holding the pedal depressed, tighten the fitting to failure, remove the hose, put on the dirt cap;
- repeat these operations for the rest of the brake mechanisms until all air has been expelled from the system and the brake pedal becomes «tough»;
- if, despite pumping, the pedal remains «soft», then there is still air in the system - its final removal is required. The inflow of air into the system may occur due to a violation of the tightness of the connections of hoses and pipelines, leakage in the cuffs of the main and working brake cylinders;
- take a test drive, during which be careful.
Bleeding the brake system with a special tool
Brake bleeder Renualt.
Attention! On vehicles with a vacuum brake booster, do not press the brake pedal while bleeding the brake system.
1. Pumping is carried out on a car standing on wheels.
2. Connect the bleeder to the brake master cylinder, wheel cylinders and brake force distribution valve.
3. Set the bleeder to a compressed air pressure of 5 bar.
4. Connect the device to a reservoir of the main brake cylinder.
5. Open the rear right wheel brake drain. Drain brake fluid for approximately 20 seconds.
6. Open the front left wheel brake drain plug. Release brake fluid for about 20 seconds.
Note. Ignore air bubbles in the priming device tubes.
6. Open the rear left wheel brake drain plug. Release brake fluid for about 20 seconds.
7. Open the front right wheel brake drain plug. Release brake fluid for about 20 seconds.
8. Press the brake pedal several times. The pedal must be "tight". Repeat the pumping procedure if necessary.
9. Disconnect the bleeder and check the brake fluid level.