Genuine Audi 100 Vacuum Pump

Audi 100 Vacuum Pump Parts and Q&A

• Vacuum Pump
  8L0-862-257-N
  Q: How can the operation of the braking system vacuum pump be checked on Audi 100?

  A:

  It is possible to test the operation of the braking system vacuum pump by disconnecting the vacuum pipe with the vacuum pump and connecting a gauge with a suitable length of hose to the pump union. Once the engine has been switched on and allowed to idle, measure the vacuum provided by the pump; hopefully after one minute, at least 500 mm Hg should be measured. When the vacuum read is much lower than this, probably the pump is faulty and it will be prudent to find consultation of an Audi/VAG dealer before coming to a conclusion that the pump is defective. The vacuum pump cannot be overhauled since no parts are available separately and in case the vacuum pump is known to be faulty, the whole pump assembly will have to be replaced.
• Vacuum Pump
  4B0-907-325
  Q: How to remove and refit the vacuum pump on Audi 100?

  A:

  Removing the vacuum pump on engines with 4-cylinders requires the first step of prising out the covers, unscrewing the retaining nuts and removing the top cover. The vacuum pump is at the back of the left hand side of the cylinder block. Detach the vacuum hose at the very top of the pump by pulling off the retaining clip, loosen the retaining bolt and remove it to remove the pump retaining clamp. Removal of the vacuum pump in the cylinder block should be done and the sealing ring should be recovered and thrown away and a new sealing ring should be used during refitting. To refit, put the new sealing on the vacuum pump and put oil on to facilitate installation. Position the slot of the drive gear with the dog of the drive shaft, making sure that it is in correct position on the drive shaft (4-cylinder engines). Reinstall the retaining clamp and tighten the retaining bolt, and reconnect the vacuum hose, and fasten it with the retaining clip and before reattaching and tightening the top cover. In the 5-cylinder engines, the vacuum pump is attached on the left-hand side of the cylinder head. To remove the pump, remove the top cover, then disconnect the vacuum hose and unscrew the retaining nuts and washers and remove the pump and its pushrod. Refitting should be done with a new sealing ring discarded. Install the new sealing ring on the pump body and fit the pushrod and manoeuvre the pump into place making sure the pushrod is in place. Install the pump on its studs, re-attach the washers and retaining nuts and tighten them on. Lastly, reattach the vacuum hose and fit into the retaining clip.