Hydraboost Noise

[davepl]

Greetings all - I put a hydra boost back into a truck that I've had in the truck before, where it worked great and silently. Then the unit came off, sat on the shelf for 10 years, and then I went and put it back on (long story).

This second time, though, it's noisy like I cannot bleed it. It's a tiny bit noisy just sitting at idle, and then if you turn the wheel or hit the brake it starts to groan.

I've done the bleeding procedure (including the one from Ford, which includes the brake pedal step) many times now and no improvement.

The shop thinks the flow is too high and is going to install a restrictor. But should I have any hope of that working?

I'm wondering if there's too much flow to the return now that there are parallel return paths and that's unloading the relief valve? Kinda grasping for theories...

Any good theory welcome!