Moaning, groaning, angry hyroboost power steering

[davepl]

Installed a Hydraboost yesterday, using a head unit that was known good (worked fine when taken off years ago). Installed it in the same car with the same PS pump that it had come out of. So in other words, I was expecting it to bolt in and work!

Which it largely does, functionally, but it's loud as heck. I assume it's air in it but neither me nor the shop can quiet it down.

I was planning to put it up on the lift and with the motor running, cycle the PS pump back and forth through the range of motion a few times, which I've heard is a good way to "bleed" the power steering.

Anything else I can or should try? Can air get trapped int he hydra boost? You can feel it in the pedal and it makes noise just like the steering wheel when you hit the brake.

Otherwise, they work fine in terms of assist and so on.

Thoughts?