Bleeding your 275 GTB/4 clutch

Discussion in 'Vintage (thru 365 GTC4)' started by airborne, Sep 6, 2017.

  1. airborne

    airborne Rookie

    Feb 19, 2013
    Northern VA
    Just replaced my clutch master and slave cylinders. A tip to (hopefully) save someone days of beating their head against a wall...
    Apply about 5-10psi of pressure on the clutch fluid reservoir. Then have your assistant work the pedal just as you would to bleed a brake fitting. Nothing else worked (gravity, pumping, vacuum, etc)

    What a pain in the ass. But positive pressure worked like a champ.
    steve meltzer likes this.
  2. GBTR6

    GBTR6 Karting

    Dec 29, 2011
    Titletown, USA
    Full Name:
    Perry Rondou
    You can also bench bleed the master to get fluid into it before connecting it to the lines.

  3. DWR46

    DWR46 Formula Junior

    Jun 19, 2012
    The problem is not the master, it is the U-shaped bend where the fluid leaves the master and starts down to the slave cylinder. Air bubbles get trapped at the top of the "U" and while fluid will bleed through the system, may times it flows under the bubble and the bubble will stay in place. You have to move large quantities of fluid quickly to move the bubble. That is what Airborne was able to do by applying pressure to the reservoir. This is a very common 275 and 330 problem.
    steve meltzer likes this.
  4. John Vardanian

    John Vardanian F1 Rookie
    Silver Subscribed

    Jul 1, 2004
    San Francisco Area
    Full Name:
    John Vardanian
    We learned this the hard way as you did some years back on a Shortnose. We found a soy sauce bottle cap that was the right fit for the reservoir mouth and fixed a nipple onto it and carefully force air into the reservoir with a bicycle pump. After days of wasting time and fluid, this trick worked.

    steve meltzer likes this.
  5. steve meltzer

    steve meltzer Formula Junior

    Sep 18, 2004
    with Enzo 8995
    Dyke, would a fairly powerful, say 25-30mm Hg, constant vacuum, as in an electric suction machine, work here? Or, is postive pressure the only practical way?
    thanx steve
  6. Motob

    Motob Formula 3
    Professional Ferrari Technician

    Nov 11, 2003
    Berkeley, CA
    Full Name:
    Brian Brown
    Suction tends to collapse the seals and possibly suck air in. It works, but not as well as pressure. While the system is pressurized, you can pump the pedal at the same time. It really works well.
    steve meltzer likes this.
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  8. mnsty

    mnsty Rookie

    Jun 12, 2005
    Torrance, Ca
    Full Name:
    Cory Muensterman
    Much easier (in the end) is to go to the hardware store and buy an pump type oil can, cut off the very end so it has just a open hose, usually small diameter metal tube, and slip a bleed hose on it. Fill it with brake fluid, pump it till the fluid is at the end of the hose, slip the hose on the bleed screw open the bleed and pump. You'll be pushing the air the way it wants to go, up. Oh yea, start with an empty reservoir. It helps to have this on hand for those jobs that are a pain in the butt. I have a friend who is a aircraft mechanic, he taught me this years ago bleeding brakes on his plane. try pushing air down that far!
    steve meltzer likes this.
  9. Jumprun

    Jumprun Karting

    Feb 7, 2012
    Southern California
    Full Name:
    T. Martinez
    Brilliant idea, yes, push the air the way it wants to go, brilliant, thanks for the tip. I already have one of those pressure bleeders that pushes fluid into the resevoir but it makes more sense to push from the bottom.
    I also have a vacuum system because I've found that even the same car does not always easily bleed the same way.
    steve meltzer and mnsty like this.
  10. mnsty

    mnsty Rookie

    Jun 12, 2005
    Torrance, Ca
    Full Name:
    Cory Muensterman
    Did it help?

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