Checking the serviceability
1. To check the function of the booster, press the brake pedal several times to relieve the vacuum, then start the engine while keeping the pedal depressed. When the engine starts, the pedal should move down noticeably as the vacuum builds up. Let the engine run for at least two minutes, then turn it off. Press the brake pedal again several times - the first time you press it, the pedal should move easily, but with each subsequent press, its elasticity should increase and the pedal travel should decrease.
2. If the amplifier does not operate as described, inspect its check valve (see Chapter 4). If the check valve is OK, try replacing the booster air filter (Chapter 5).
3. If the amplifier continues to operate with malfunctions, the unit itself is damaged. Apart from external components, its parts cannot be purchased separately, so a faulty amplifier must be replaced.
Removal
Note: A new amplifier gasket will be required during installation.
4. Remove the master cylinder (see Chapter 8).
5. Loosen the clamp and disconnect the vacuum hose from the check valve on the booster. If the hose still has the original Renault clamp, cut it - it needs to be replaced; when installing, use a standard worm-type clamp.
6. Undo the rubber belt and separate the expansion tank from the booster.
7. Working inside the car, remove the spring clip and remove the pin securing the booster pushrod to the brake pedal. Pay attention to the spacer gasket that is located on the inside of the pedal (see illustrations).
3.7a. Remove the spring clip (marked with an arrow)...
3.7b....then remove the pin securing the booster pushrod to the brake pedal; the amplifier mounting nuts are marked with arrows
8. Remove the four nuts and washers securing the booster to the engine compartment bulkhead. Return to the engine bay and remove the booster, taking note of the gasket installed on the back of the block.
Installation
9. Before installation, make sure the booster pushrod length is adjusted correctly. To do this, remove the gasket and take the measurements shown in the figure (see illustration).
3.9. Adjusting the length of the booster push rod: C - Push rod fork; L - 110 mm; R - Push rod nut; X - 22.3 mm.
If adjustment is necessary, change the length "L" by loosening the lock nut and moving the push rod fork in the desired direction. To change the "X" distance, move the "P" nut. After adjusting, ensure the fork locknut is tight.
10. Inspect the check valve O-ring for damage and replace it if necessary.
11. Install a new gasket on the rear of the amplifier and install the unit into the engine compartment.
12. When working inside the car, make sure that the booster pushrod is properly connected to the brake pedal. Install the booster mounting nuts/washers and tighten them to the torque specified in the Specifications.
13. Place the spacer on the inside of the pedal. Install the pushrod pin and secure it with the spring clip.
14. Install the expansion tank into its bracket and secure it with a rubber belt.
15. Connect the vacuum hose to the booster check valve and securely tighten its mounting clamp.
16. Install the master cylinder (see Chapter 8).
17. Finally, start the engine and check the vacuum hose connection to the booster for leaks. Check the operation of the amplifier as described at the beginning of this Chapter.