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    1. #1
      Join Date
      May 2024
      Mesa Arizona
      Country Flag: United States

      Need some help with hydro-boost issues

      Thank you to anyone that helps its much appreciated!

      we ordered the hydro-boost blackout kit from POL part#( HB-T6772WB) and the hydro-boost does not seem to be giving any assist. Brake pedal is the same stiffness whether the engine is running or not, I am getting full throw for the master cylinder, all brakes are new, no air in the brake system. Here is a list of the parts we have installed:

      Power steering fluid: Royal Purple® Max EZ®
      Front Brakes: wilwood 140-11290-R
      Rear Brakes: wilwood 140-16711-DR
      Power steering pump: GM type II power steering pump

      Power Steering lines routed the same as in the diagram of the blackout kit, just has a remote reservoir instead. All brake lines are new, all flex lines are new, all rotors are new, rear axle is new, brakes stop rotors from spinning, just doesn't seem to have any assist from hydroboost. All lines are AN high pressure Lines. Pedal is stiff with the engine on or off. If I hold the brake and start the engine, there is no change in pedal pressure, pedal also returns to top position when the brake is released. Power steering works fine, no issues, brakes have been bled 5+ times, no air in lines. I just need guidance on the hydro-boost, as I am not extremely familiar with them, and I might need a replacement booster... I have removed the return line from the booster to ensure there was no backpressure, but ther is no fluid coming out if the return while braking or while pumping. Let me know what you think.

      here is the power steering diagram:
      Click image for larger version. 

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      Here are pictures of the lines and routing:
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    2. #2
      Join Date
      Jul 2008
      Country Flag: United States
      Teeing the HB return into the box return like that is a no no. Even when you get the system working you will have issues with pedal knock back as the fluid will hit that 90 and build pressure. You need to run separate returns from HB and box to reservoir for a trouble free install. Or at LEAST Y the hoses together as close to the reservoir as possible to reduce any pressure from the box being fed back to the HB return. It's like you've plumbed your fuel return line into the pressure line.. there's no place for the HB to exhaust..

      Your lines are ran correctly and the HB system should work.

      Out of curiosity, do you have an AN6 block off that you can put on the tee and run the engine w/ the HB return loose to see if fluid is flowing? I know you said there's no fluid coming out but wondering if that was w/ engine off? Either way, you may have a bad HB as there should be fluid coming out of the pressure reservoir when pumping the pedal.. Also crack the return loose @ the HB and see if you have any fluid flowing there to eliminate the return hose as a restriction..

      I'm running a HB system out of a 2005 Yukon I pulled out of a junkyard and am running all factory hoses. It looks like medusa's ass in the engine bay but I've got 36k+ trouble free miles including autocross, road racing, drag racing, trips, cruises, parades, etc..
      Project Salty - 1964 4 door Malibu, beaten, neglected, red headed foster child
      Cammed LQ4 / T56 Swap Project Thread <-click to read! 😁

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