Question about 1993 Buick LeSabre

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Leak from master cyclinder

93 buick lesabre leaking form master cyclinder, HELP

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  • 6 more comments 
  • sgraham5 Nov 13, 2008

    it is between the master cylinder and the brake booster.


  • sgraham5 Nov 13, 2008

    could you explain it in detail. My brother thought there was a gasket between them and the dealer said that there wasn't and i would have to repalce the master cyl.

  • Anonymous Dec 08, 2008

    How do i bleed the brakes on a 1995 Buick LeSabre with ABS

  • Anonymous Jan 22, 2009

    brake peddle sometimes fades when prressed down

  • mike harris
    mike harris May 11, 2010

    Hi sgraham5, is this leak on top (the cover/cap) or between the master cylinder and the brake booster?

  • Anonymous Mar 15, 2014

    Adjusting shifter linkage on 93 Buick lesabre

  • Anonymous Mar 16, 2014

    93 Buick lesabre won't shift until you rev engine

  • Anonymous Mar 27, 2014

    The water pump is leaking slightly. How can I tell how serious the leak is?



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Hi sgraham5,this is a pretty simple fix really,and not very expensive,do you plan to do the repair yourself or are you going to take it in? the diaphragm between the cyl and booster is shot and needs to be replaced you will have to take off the master cylinder. If you do this yourself buy a haynes or chilton manual for your car (which is great to have anyway) and you will have no problems,because this is related to your brakes you must make sure it is done right.If you like I can explain this in detail to you via chat as there are a few critical issues here let me know and good luck to you friend.

Posted on Nov 13, 2008

  • 2 more comments 
  • mike harris
    mike harris Nov 13, 2008

    Hey sgraham5, sure we can first there are 4 types of master cylinder for your car and it may not have the seal.Mastercylinders range from $30 - $180 dollars A1 cardone , (slim cast design) Centric which has a sensor lead, PBR (normal plastic tank on topside no electronics) which I think is the one you have and Raybestos so you need to determine which one it is, basically you will disconnect the 2 brake lines and then you will remove the 2 nuts that hold the master cylinder in place, slide the mastercylinder out.If you have to replace the complete master cylinder make sure before you install it that you bench bleed itMaster cylinders MUST be
    bench bled outside the vehicle and without any other components
    attached. This means that if a new master is equipped with a booster,
    proportioning valve and plumb lines attached, they must all be removed
    prior to bench bleeding.
    Be sure to place the master cylinder
    level in a vice and secure it properly. If the cylinder isn't level,
    not all the air will be able to be removed from the master cylinder.
    Remove the master cylinder top and fill with fresh brake fluid to the
    appropriate level as indicated in the master cylinder-- generally about
    1/2 to 1 inch from the top of the reservoir.
    Insert a pair of
    short, looped brake lines or rubber tubing from a bench bleeding kit,
    (available at nearly all auto parts stores), into the two side ports of
    the master cylinder. (Note: on dual-ported master cylinders where there
    are four ports, choose one side and use both ports on that one side to
    perform the bleed process.) Insert one rubber tube into each of the
    plastic fittings. and the loose ends should be inserted into the master
    cylinder reservoir. The plastic tab should be used to hold the tubes in
    place by slipping it over the reservoir separator and the hoses through
    the round holes.

    a wooden dowel, a blunt metal rod, or a large Philips screwdriver,
    compress the master cylinder plunger with slow, deep strokes. Once the
    large bubbles have subsided, it should become increasingly more
    difficult to compress the master cylinder piston. Continue to do so
    with slow, short strokes at the bottom of the piston stroke until no
    more bubbles appear. The rubber hoses and plastic fittings may be
    removed from the master cylinder. Secure the master cylinder top,
    install the master cylinder and leave enough room on the mounting nuts
    to allow for some movement of the master. This will allow you some
    breathing room while screwing in the hydraulic lines to help prevent
    cross-threading the fittings.You have now installed the component and if all went well saved a lot of time bleeding the system once installed.

  • mike harris
    mike harris Nov 13, 2008

    Now to bleed the brakes part 1: to ensure you are safe :)start with a couple of 8-ounce
    cans of fresh brake fluid. An unopened can has a long shelf life. An
    opened can should be discarded within a few weeks. Get the vehicle up
    in the air and remove all four wheels. Well, okay, you might be able to
    do this with the wheels on if you can swing a wrench on the bleeder
    So, your next task is to make
    sure the bleeder valves can be loosened. You'll need a box wrench that
    fits the bleeder bolt. A crescent wrench or Vise-Grip probably will
    just round off the bolt's flats. A little penetrating oil drizzled on
    the bolts the day before will help. So will some judicious tapping with
    a hammer to break up any corrosion. Loosen the bolts, but leave them

    If you can't turn the bleeders without breaking them off, you'll
    need to replace the brake calipers or wheel cylinders. See the above
    notation about penetrating oil and light hammer taps before applying
    enough torque to break these minuscule, hollow bolts.

    Sneak into the kitchen and appropriate the small turkey baster.
    Remove the top to the master cylinder reservoir and **** out as much of
    the old squid ink as you can. Clean any sediment out of the reservoir
    with a clean, lint-free rag. Do not spill any brake fluid on any
    painted surfaces — it will remove the paint pretty much immediately.

    Get a piece of clear plastic tubing (aquarium tubing is fine, and
    it's cheap). Push one end of the tube over the brake bleeder bolt at
    the right rear of the car. Put the other end of the tube into a small,
    clear bottle with an inch or two of clean brake fluid in it. (This will
    keep air from being sucked back into the brake cylinder or caliper.)
    Put a piece of 1 x 4 lumber or some other spacer under the pedal to
    prevent the pedal from traveling too far when line pressure is
    released. Top off the master cylinder reservoir with fresh fluid and
    put the cover back on the reservoir. Fluid will squirt out of an open
    reservoir every time the pedal is released.

  • mike harris
    mike harris Nov 13, 2008

    Part 2: this procedure is used from a mech site so bear in mind that you have new fluid not squid ink so all you have to worry about is making sure the master cylinder dosnt run empty while bleeding ok just keep topping it up. so,
    Cue the Helper
    Your helper needs to be someone who can follow instructions exactly. He
    or she won't get dirty hands so you don't need to pull one of your pals
    away from the ballgame. A teenager in a white dress will do fine. Have
    your helper sit in the driver's seat and await your orders. Here's the
    drill: You say "down." He or she depresses the brake pedal with about
    the same amount of force needed to keep the car from rolling forward at
    a traffic light. Then your helper says "down" and keeps the pressure
    on. When you hear the call, warn your helper that the brake pedal is
    about to sink underfoot and to keep the pressure on constantly. Then
    crack the bleeder bolt a quarter-turn.
    Some of the old, contaminated
    fluid will trickle down the tubing into your bottle. When the trickle
    stops, close the bleeder. Then you say "up." Your helper says "up," and
    removes his or her foot from the pedal.

    Repeat this process until fresh, clear fluid comes from the
    bleeder. Any out-of-sequence moves can **** air into the caliper. Yes,
    the end of the tubing is submerged in fluid, but air can travel past
    the threads on the bleeder bolt into the caliper if there's ever any
    negative pressure in the system while the bleeder is cracked.

    Every half-dozen or so iterations, top off the reservoir with fresh
    fluid. Do not allow the reservoir to get more than half empty — air can
    be sucked into the master cylinder unless the fluid level remains well
    above the bottom of the reservoir that feeds the cylinder.

    Once clean fluid is coming out of the brake, snug the bleeder bolt
    and move your operation to the left rear wheel and start all over
    again. Next repeat the process with the right front and finally with
    the left front. Follow that with a few strokes of fresh fluid from all
    four, again. Don't forget to keep the reservoir topped off.

  • mike harris
    mike harris Nov 13, 2008

    good luck my friend let me know how you make out or if you have any concerns, theres a lot of words here but its not that bad good luck



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if this answer your question. please rate the answer
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