If the brake booster does not work when you check the brakes, it should be replaced.
You will need: a flat-blade screwdriver and a 13 mm socket.
Disconnect the negative battery terminal wire.
Disconnect the booster hose to the intake manifold by prying the hose check valve with a screwdriver.
Remove the brake master cylinder (see "Renault Logan Brake Master Cylinder").
If you have sufficient skills, you can leave the brake master cylinder in place; simply disconnect it from the brake booster and move it forward without disconnecting the lines.
Using a screwdriver, remove the two soundproofing pad holders and remove the pad.
Disconnect the vacuum booster pushrod from the brake pedal by unfastening the spring pin retainer from the pedal and, By squeezing the plastic retaining ring, remove the pin from the holes in the pedal and the pushrod fork.
Replace the brake booster pushrod pin if it is worn or the spring clip and retaining ring are damaged.
Unscrew the four Remove the brake booster mounting nuts from the front shield and remove the booster.
Adjustment dimensions of the brake booster: X = 22.3 mm, L = 145.8 mm.
Install the brake booster and all removed parts in the reverse order of removal.
Before installation, check the booster adjustment dimensions and, if necessary, restore them by turning the booster rod adjustment bolt (dimension X) and the pushrod fork with the locknut (dimension L) loosened.
The booster rod adjustment bolt is secured against loosening during operation with anaerobic thread locking compound.
Fill the brake fluid and bleed the system (see "Changing the Renault Logan Brake Fluid").