Hydroboost squealing

[redneck_reed78]

Under agressive braking the power steering pump squeals and I get pedal feedback almost feels like ABS feedback and there's not as much stopping power as I'd like. Truck is an 87 one ton with hydroboost. New master cylinder and PS pump. Also worth noting that I replaced the master cylinder due to a leaky cap but the new one still leaks, so I'm wondering if something is possibly pushing fluid out of it?

 

[1942GPW]

It’s probably the hydro boost unit itself. I put a used on in my truck when replacing a vacuum power brake system and it did what you are referencing. I replaced it with a re-manufactured from oreillys and has been fine since. You will need to swap some parts over to the new unit. It’s possible you might need to bleed the hydro booster as well but that didn’t work for me.