Brake bleeding units

Frequently Asked Questions About Brake Bleeding Tools

After changing the brake fluid or performing work on the hydraulic brake system, any air in the system must be reliably removed. Professional brake bleeder tools enable a controlled fluid change at a defined operating pressure. Here, we answer common questions about pressure bleeding, vacuum bleeding, adapters, and the proper bleeding of modern brake systems.

• Why does a hydraulic brake system need to be bled?

  Brake fluid is virtually incompressible, whereas air is compressible.
  
  If air is present in the hydraulic system, the pedal feel may change and pressure transmission may be impaired.
  
  After opening the brake system or after certain repairs, any air present must therefore be properly bled from the system.

• When does a brake system need to be bled?

  Bleeding may be necessary, for example, after:

  • Changing the brake fluid
  • Replacing brake lines or brake hoses
  • Working on the master cylinder
  • Replacing brake calipers or wheel cylinders
  • Opening the hydraulic brake system
  • Certain work on ABS/ESP hydraulic units

  The specific procedure follows the vehicle manufacturer’s instructions.

• How does a brake bleeder with positive pressure work?

  The device is connected to the brake fluid reservoir using a suitable adapter.
  
  New brake fluid is then pumped into the system at a specified operating pressure.
  
  The old brake fluid or any trapped air is systematically purged through the bleed valves.
  
  This allows the fluid change to be performed continuously.

• What pressure is used when bleeding the brakes?

  There is no standard operating pressure for all vehicles.
  
  The permissible pressure depends on the vehicle and the braking system.
  
  With compatible Leitenberger units, for example, the operating pressure can be adjusted continuously.
  
  The vehicle manufacturer’s specifications and the permissible range of the unit being used are always decisive.

• Why is the product pumped directly from the original container?

  With compatible Leitenberger brake bleeder units, the original container serves as a storage tank.
  
  This means the new brake fluid does not need to be transferred to a separate unit tank first.
  
  This reduces the number of handling steps and can minimize the risk of accidental contamination.

• What happens if the brake fluid container is empty?

  Compatible Leitenberger devices are equipped with an automatic shut-off feature that activates when the supply container is empty.
  
  This is designed to prevent the device from continuing to operate uncontrollably after the supply has been completely depleted.
  
  The exact function depends on the specific model of the device.

• Can one person bleed the brakes by themselves?

  Yes.
  
  Pressure-based brake bleeding units are designed for single-person operation.
  
  The unit maintains or generates the required operating pressure while the mechanic works on the designated bleed points on the vehicle.

• Which brake fluids can be used with these devices?

  That depends on the specific model of the unit.
  
  The corresponding Leitenberger BSG units, for example, are designed for common glycol-based brake fluids such as DOT 3, DOT 4, DOT 4 Plus, and DOT 5.1.
  
  Only fluids for which the specific unit is approved may be used.

• Why do you need a compatible brake bleed adapter?

  The brake bleeder is connected to the brake fluid reservoir.

  Since reservoirs and caps vary from one vehicle to another, the adapter must:

  • fit mechanically,
  • lock securely,
  • and seal against pressure.

  Various brake bleeder adapter kits are available for this purpose

• Is there a universal adapter for brake bleeders?

  There are universal adapter solutions available for various container shapes.
  
  For many vehicles, however, a vehicle-specific adapter—or one designed to fit the vehicle’s specific design—is the better solution.
  
  Extensive ranges of adapters are therefore available for multi-brand repair shops.

• Can a brake bleeder tool also be used to bleed the clutch?

  For hydraulic clutch systems and vehicles or equipment designed for such systems, yes.
  
  Various Leitenberger brake service units are specifically designed for brake, clutch, and ABS systems.
  
  The procedure depends on the respective vehicle manufacturer.

• What is the difference between pressure venting and vacuum venting?

  In pressure bleeding, new brake fluid is forced through the system from the reservoir under controlled positive pressure.
  
  In vacuum bleeding, fluid or air is drawn out at a suitable location using negative pressure.
  
  Both methods can be used depending on the application.
  
  The method intended for a specific vehicle depends on the brake system and the manufacturer’s instructions.

• Do ABS or ESP systems need to be bled specifically?

  On some vehicles, additional bleeding procedures may be required for ABS/ESP hydraulic units.
  
  This may include, for example, activating valves or pumps via a diagnostic system.
  
  Therefore, when working on these components, always follow the vehicle-specific bleeding procedure.

• How can you tell if there is still air in the system after bleeding it?

  Signs of this may include, for example, an unusually soft or spongy pedal or unusual pedal feel.

  However, this alone does not automatically indicate air in the system.

  If the problem persists, you should also check for leaks, inspect the hydraulic components, and, if necessary, check the brake pressure in the vehicle's braking system.

• Can a brake bleeder tool also be used to perform a leak test?

  Some brake service units allow for pressurization within their intended operating range to check the system.
  
  For a targeted test of a completely drained brake system, Leitenberger also offers the LDS 01_BS, which uses test gas and measures pressure drop.
  
  These are different testing methods and should not be confused with one another.

• Which brake bleeder is right for my workshop?

  The selection depends in particular on:

  • Number of daily brake services
  • Passenger car or commercial vehicle
  • Desired package size
  • 12-V or 230-V power supply
  • Stationary or mobile use
  • Desired vacuum function

  For a multi-brand repair shop, a sufficient selection of brake bleeder adapters should also be considered.

  You can find additional solutions under Test and Service Equipment for Brake Systems.