You can check the vacuum booster on a car with the engine off, press the brake pedal 4-5 times.
Keep the pedal pressed and start the engine
If the booster is working properly, the pedal should "sink" slightly when the engine starts.
The check valve, which is located in the tip of the vacuum hose, is designed to be able to brake the car with sufficient efficiency when the engine suddenly stalls.
To replace the vacuum booster, remove the check valve.
We pry it with a screwdriver and remove it from the vacuum booster housing. The valve is sealed with a rubber bushing.
To check the valve, disconnect the tube from the receiver, press the clamps (shown by arrows in Figure 2)
Disconnect from the receiver (Fig. 3)
Remove the check valve together with the tube
You can check its condition by creating pressure in the hose using a suitable rubber bulb.
Air should pass from the vacuum booster, but not in the opposite direction.
A leaky valve is subject to replacement.
We check the condition of the O-ring of the tube tip (Fig. 6)
We take out and inspect the rubber bushing. There should be no breaks or cracks on the bushing.
After that, unscrew the two nuts securing the brake master cylinder.
Without unscrewing the tubes, carefully remove the master cylinder from the studs, and bending the tubes slightly, move it to the side.
Using a screwdriver, pry off the noise insulation holders
Remove the noise insulation
Remove the plastic stopper from the pushrod mounting pin
Disconnect the spring retainer
Remove your finger
Unscrew the four nuts securing the vacuum booster
Take out the vacuum booster.
Installation
Before installing the booster, you need to check the condition of the gasket between the vacuum booster and the shield front.
Before installing the booster, check the size L = 145.8±0.5 mm, adjust if necessary.
We install the vacuum booster and tighten it with a 13 head to the front shield. Tightening torque of nuts 21 Nm (2.1 kgf.m).
Connect the vacuum booster to the brake pedal, for which install a new connecting axle in the holes of the booster pusher and the brake pedal and snap the axle flag onto the pusher rod.
The axle is installed only by moving from right to left and from top to bottom. Before installing on the axle, apply 1 g of Molycote33m grease.
Install the noise-insulating pad and secure it with two spring washers (technological tube).
Install the brake booster check valve.
Install the brake master cylinder.
Bleed the brake system and clutch hydraulic drive.
Adjust the brake signal switch.
Check the efficiency of the service brake system.