Hydroboost System Bleeding Instructions


After installing a steering gear or pump in a vehicle with a hydraboost braking system, you may discover odd problems after bleeding the system in the normal way. The problems would be lack of power assist in your brakes, lack of power steering or some combination of the two. The reason is air in the system. Air in the system can cause all kinds of strange problems with the hydraboost system.

A manual will tell you to use a vacuum bleed system which is very complicated and requires tools that many shops do not have. Another alternative that we find works well is as follows:

  1. Jack the vehicles up so the tires are just clear of the ground.
  2. Make sure the steering wheel is centered and start the engine.
  3. SLOWLY turn the steering wheel to the right half an inch from center and then left half an inch from center. Continue to do this SLOWLY increasing the amount you turn the wheel half an inch at a time until you are going lock to lock. This process should take at least a half hour.
  4. During this process, it is important that the fluid level in the pump remain above the pump casting so you do not introduce more air in the system.
  5. If you get small bubbles appearing in the fluid, you have to shut the vehicle off and walk away until the bubbles are all gone. If small bubbles re-appear, you need to shut the engine off again and take another break. There is no way to speed this process.
  6. Once you have gone through this process the steering and brakes should work.

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