Volkswagen Cars 2000-05

Hydraulic System

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Hydraulic System Bleeding



  1. Disconnect the negative battery cable.
  2.  
  3. Clean the top of the brake master cylinder fluid reservoir before opening it.
  4.  
  5. Be sure that there is adequate fluid in the clutch master cylinder fluid reservoir before attempting to bleed the system.
  6.  
  7. Check the fluid level throughout the bleeding procedure.
  8.  
  9. Connect a hose to the bleeder valve fitting on the clutch slave cylinder.
  10.  
  11. Submerge the other end of the hose into a container of clean brake fluid.
  12.  
  13. Push the clutch pedal down while opening the bleeder on the clutch slave cylinder.
  14.  
  15. Watch for air bubbles escaping from the hydraulic system.
  16.  
  17. Close the bleeder before releasing the clutch pedal.
  18.  
  19. Repeat the procedure until no more air bubbles are seen.
  20.  
  21. Reinstall the rubber inspection cover to the bell housing.
  22.  
  23. Top off the clutch master cylinder fluid reservoir and install the diaphragm and cap securely.
  24.  
  25. Reconnect the negative battery cable.
  26.  
  27. Check the clutch for proper operation.
  28.  

  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. The clutch and brakes share the same reservoir. Clean all dirt and grease from the cap to be sure no foreign substances enter the system.
  4.  
  5. Remove the cap and diaphragm and fill the reservoir to the top with the approved DOT 3 or 4 brake fluid. Fully loosen the bleed screw which is in the slave cylinder body next to the inlet connection.
  6.  
  7. At this point bubbles of air will appear at the bleed screw outlet. When the slave cylinder is full and a steady stream of fluid comes out of the slave cylinder bleeder, tighten the bleed screw.
  8.  
  9. Refill the reservoir and cap it. Exert a light load of about 20 lbs. (9 kg) to the slave cylinder piston by pushing the release lever towards the cylinder and loosen the bleed screw. Maintain a constant light load; fluid and any air that is left will be expelled through the bleed port. Tighten the bleed screw when a steady flow of fluid with no air is being expelled.
  10.  
  11. Fill the reservoir fluid level back to normal capacity, if necessary repeat Step 4.
  12.  
  13. Exert a light load to the release lever but do not open the bleeder screw as the piston in the slave cylinder will move slowly down the bore. Repeat this operation 2-3 times; the fluid movement will force any air left in the system into the reservoir. The hydraulic system should now be fully bled.
  14.  
  15. Check the operation of the clutch hydraulic system and repeat this procedure, if necessary.
  16.  

The clutch and brake hydraulics use an approved DOT 4 brake fluid in their systems. The hydraulic system should be bled periodically, usually a minimum of every two years, or more often under severe use. Brake fluid can absorb moisture. Because condensation is heavier than brake fluid, and under normal conditions, will not mix with it, the sediment and condensation tend to collect in the slave cylinder and in the bottom of the master cylinder reservoir.

If possible, before bleeding the system, use a siphon gun or a cooking baster to remove the old fluid, or remove the reservoir and flush it using a recommended brake cleaner or rubbing alcohol. If necessary, the reservoir can be flushed while removed from the vehicle using lightly pressurized water, however the reservoir must be flushed with brake cleaner or rubbing alcohol and dried completely before installation.

There are a number of brake hydraulic bleeders available that use vacuum to 'pull' the fluid through the hydraulic system. The advantage these tools offer is that the system can be bled without the help of an assistant.


CAUTION
Bleeding or flushing the clutch hydraulic system with dirty or contaminated fluid may result in component damage.

When bleeding a clutch hydraulic system, always observe to following guidelines:



NEVER reuse brake fluid
 
Always bleed the system using fresh fluid
 
Do NOT use fluid which has been left uncapped
 
Use a recommended fluid which is compatible with the existing fluid
 

  1. Fill the reservoir with fresh fluid.
  2.  
  3. Fit a flare or box end wrench onto the slave cylinder bleeder screw.
  4.  
  5. Attach a (clear if available) rubber tube to the slave cylinder bleed screw and suspend it into a suitable clear drain container partially filled with brake fluid.
  6.  
  7. Open the bleeder screw and have an assistant press the clutch pedal to the floor.
  8.  
  9. While holding the clutch pedal to the floor, close the bleed screw.
  10.  
  11. Slowly release the clutch pedal to its fullest extension and recheck the reservoir fluid level. Top off as necessary.
  12.  
  13. Repeat the above steps until the fluid exiting the bleed screw is clean and free of all air bubbles.
  14.  
  15. Top off the clutch master cylinder reservoir as necessary.
  16.  



Click image to see an enlarged view

Fig. A vacuum tester and a bleeding attachment (shown bleeding the brakes here) eliminate the need for a helper. These units are available from automotive vendors

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. The clutch and brakes share the same reservoir. Clean all dirt and grease from the cap to be sure no foreign substances enter the system.
  4.  
  5. Remove the cap and diaphragm and fill the reservoir to the top with the approved DOT 3 or 4 brake fluid. Fully loosen the bleed screw which is in the slave cylinder body next to the inlet connection.
  6.  
  7. At this point bubbles of air will appear at the bleed screw outlet. When the slave cylinder is full and a steady stream of fluid comes out of the slave cylinder bleeder, tighten the bleed screw.
  8.  
  9. Refill the reservoir and cap it. Exert a light load of about 20 lbs. (9 kg) to the slave cylinder piston by pushing the release lever towards the cylinder and loosen the bleed screw. Maintain a constant light load; fluid and any air that is left will be expelled through the bleed port. Tighten the bleed screw when a steady flow of fluid with no air is being expelled.
  10.  
  11. Fill the reservoir fluid level back to normal capacity, if necessary repeat Step 4.
  12.  
  13. Exert a light load to the release lever but do not open the bleeder screw as the piston in the slave cylinder will move slowly down the bore. Repeat this operation 2-3 times; the fluid movement will force any air left in the system into the reservoir. The hydraulic system should now be fully bled.
  14.  
  15. Check the operation of the clutch hydraulic system and repeat this procedure, if necessary.
  16.  

 
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