Hydraulic system — bleeding (VW Lt 28)

1. Two independent hydraulic circuits are used, one for the front brakes and one for the rear.

2. If you disconnected the master cylinder, you need to bleed the entire brake system, but if you only worked on one

component, then you can only pump the corresponding circuit.

3. When pumping, follow this sequence:

Posterior chain

• Right hand drive - left wheel, right wheel, pressure regulator
• Left hand steering wheel - right wheel, left wheel, pressure regulator

Front chain

• Steering wheel on the right - left wheel, right wheel
• Left-hand drive - right wheel, left wheel

Pumping - a two-person method

4. Prepare a clean glass jar and a piece of plastic tubing of suitable length that fits tightly onto the bleed nipple. Enlist the help of an assistant.

5. Before starting bleeding, make sure all tubes and hoses are in good condition and all hydraulic fittings are securely tightened. Be careful not to allow brake fluid to come into contact with painted surfaces, otherwise the paintwork will be seriously damaged. Wash away any spilled liquid immediately with cold water.

6. If brake fluid is leaking from the master cylinder due to a leak in the system, make sure the cause is identified and corrected before proceeding; otherwise, there is a high risk of serious damage to the braking system.

7. To bleed the system, clean the area around the bleed nipple on the wheel cylinder. If the hydraulic system was only partially disconnected and precautions were taken to prevent further loss of hydraulic fluid, only that portion of the system should be bled. However, when bleeding the entire system, start from the wheel located farthest from the brake cylinder.



8. Remove the cap and fill the brake cylinder reservoir. Check the fluid level periodically during bleeding and top up as needed.

9. Break the vacuum in the brake booster by pressing the brake pedal sharply several times.

10. Connect one end of the flexible tube to the bleed nipple and lower the other end into a glass jar filled with a layer of hydraulic fluid sufficient to cover the tube. Open the bleed screw half a turn and have your assistant slowly press the brake pedal all the way down and then slowly release it. Tighten the bleed screw at the end of each pedal stroke to prevent escaping air from entering back into the system. Repeat these steps until the hydraulic fluid is completely clean and without bubbles starts to come out of the tube. Now tighten the bleeder screw and remove the auxiliary tube.

Pumping - Using the One-Way Valve Method

11. Specialized stores sell a fairly large number of kits that allow you to bleed your brakes yourself. It is recommended to use one of these kits as they make the process much easier and also prevent escaping air and fluid from getting back into the system.

12. If you are using the pump kit yourself, connect the outlet pipe to the pump connection, and then unscrew the connection by half a turn. If possible, position the device so that it can be seen from the vehicle, then slowly depress the brake pedal and release it slowly as well. The one-way valve will not allow any air that has escaped back into the system at the end of each press. Repeat this operation until clean, bubble-free brake fluid comes out of the tube. Now tighten the bleeder screw and remove the tube from it.

Pumping - using the pressure method

13. Brake system bleeding kits are also available from auto parts stores and typically use the pressure from the spare tire.

14. With a pressurized container connected to the master cylinder, bleed the system by simply opening each nipple in turn and allowing the fluid to flow until it runs clear and free of bubbles - just as you would open a regular faucet.

15. When using this system, a large reserve of hydraulic fluid ensures that air does not enter the master cylinder during bleeding.

16. This method is especially effective when bleeding "difficult" systems, as well as for bleeding the entire system during systematic maintenance.

All systems

17. If you are bleeding the entire brake system, then the above processes should now be carried out with the remaining wheels, ending with the wheel that is located closest to the master cylinder. Remember to check the brake fluid level in the reservoir at regular intervals and top it up if necessary.

18. After completing the work, check the brake fluid level again, top it up if necessary and securely install the reservoir cap. Check the feel of the brake pedal, which should be "strong and firm," without the "spongy" feel that indicates air in the system.

19. Discard used brake fluid as it is likely contaminated with moisture, air and dirt, making it unsuitable for further use.