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Thread: Hydro-Boost

  1. #1

    Default Hydro-Boost

    I have a 1994 K2500,4x4 Suburban and I have fluid leaking from between the M.C. and the Hydro-Boost. I am not sure if it is Brake or Steering fluid. I have been looking for answers all over the web concerning this problem. Since I have never seen a Hydro-Boost before I don't know what the source of the leak could be or what to expect if I take it apart. I have tried, with no success, to find a detailed diagram of the actual Hydro-Boost. I am hoping it is just a worn gasket or "o" ring. Can anyone help me?

  2. #2
    TrailLeadr's Avatar
    Join Date
    Jun 2005
    Coventry, Rhode Island


    I've actually had a leak similar to what you're describing. In my case it was the O-rings in the hydro-boost unit. The unfortunate thing is that the O-rings in that unit are wide and flat, and not really user serviceable. There are two O-rings on the shaft. You could probably replace one O-ring with either two or three normal rings of the correct diameter.

    The other thing is that it could be the master cylinder that is leaking as you already know. However I would put my money on the booster. Besides servicing the booster is a lot easier in terms of bleeding the system.

    I don't have any diagrams that I can share with you on the booster, since I don't think they intended for anyone to service it rather than replace it. However I can tell you it was not difficult to work on.

    Sorry I can't be of more help, but if you feel competent enough to tackle a master cylinder rebuild, then the hydro boost will be a cake walk.
    Rhode Island

  3. #3


    Having had the same problem on two Suburbans in the last 6 months I'd bet it's the power steering leaking. The seals betwwen the Hydro Boost and the M/C are designed to stop flow from the power steering section of the Hydro Boost, the M/C is dry in that area.
    You cant get replacement seals from any dealers or parts stores (I got a set for the first truck from a relative at the GM assembly plant). The only way to fix it is to replace the Hydro Boost with a new unit which will come with new seals at both ends.
    I tried to jury rig some seals on the first Suburban and had no success, the seals are a one of a kind item.
    I did get a schematic of the Hydro Boost unit from a friendly dealer tech, it doesnt show much, at the dealership it's considered a non serviceable part.
    Last edited by tbplus10; 07-19-2007 at 09:38 AM.

  4. #4


    So, basicly, in order to do this so it won't leak again is to buy a new H.B. unit and install it or possibly have it sent out and rebuilt? If I order one how can I be sure it is the correct one? I s there some way I can cross refrence my VIN number to a part number? A web site maybe?
    Thank you so much. I truely appreciate you're help. This thing has me all kinds of confused.

  5. #5
    TrailLeadr's Avatar
    Join Date
    Jun 2005
    Coventry, Rhode Island


    Your best bet is to just swap it out with one from a local parts store, or order it from

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