275 GTB Clutch Fluid leak | FerrariChat

275 GTB Clutch Fluid leak

Discussion in 'Vintage (thru 365 GTC4)' started by massimofinance, Sep 4, 2014.

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  1. massimofinance

    Nov 24, 2004
    39
    About a year ago, I went to drive my 275 and found the Clutch reservoir dry. Could not find a puddle of fluid under the car. I went through the process of replacing the master cylinder, the tube to the slave, the slave, and the tube from the reservoir to the master. I took out the reservoir and bench tested it for leaks- none. This past weekend, I tightened everything down, bleed the clutch, shut the bleeder tight, and topped off the reservoir. Two days later, I check, and the reservoir is empty. There are two puddles of fluid under the car, on the floor, almost directly under where the Master cylinder is. The engine bay is dry- no residue or a leak, nothing.

    I am thinking that it is leaking from the master, right where the Peddle pin enters the Master, in the cockpit, and maybe dripping down the inside cockpit side of the firewall? I adjusted the peddle pin per the book (it says to have a tiny bit (0.25?) of free play before it enters the master). Anyone else have a thought? This is driving me nuts...
     
  2. 12659

    12659 Formula Junior

    Oct 6, 2005
    349
    Seattle WA. USA
    Full Name:
    mark
    Check the slave cylinder
     
  3. massimofinance

    Nov 24, 2004
    39
    Thanks, but it is dry- what exactly am I checking it for?
     
  4. John Vardanian

    John Vardanian F1 Rookie

    Jul 1, 2004
    3,080
    San Francisco Area
    Full Name:
    John Vardanian
    I would follow the hydraulic trail from the reservoir to slave cylinder, there must be an evidence of a leak. Unlike oil, the DOT4 fluid can dry up, so you may not find a wetness, but there should be some evidence of a leak. For instance, painted parts will delaminate, steel parts will rust, etc.

    john
     
  5. michael bayer

    michael bayer Formula 3

    Aug 4, 2004
    1,293
    Does your exhaust look different since this began? M
     
  6. 8339

    8339 Karting

    Oct 17, 2006
    194
    Maryland
    Full Name:
    Richard
    Do yourself a favor, anytime I replace a slave cylinder the master and the hose are replaced at the same time. If one hydraulic cylinder is is worn or leaking, then in most cases the other one is not far behind. If you look inside the drivers footwell where the master is mounted, you'll probably see evidence of brake fluid leaking. If you do make sure you wash it down with water and baking soda to neutralize the fluid and corrode the metal around it.
     
  7. 2NA

    2NA F1 World Champ
    Consultant Owner Professional Ferrari Technician

    Dec 29, 2006
    18,221
    Twin Cities
    Full Name:
    Tim Keseluk
    It's a simple hydraulic system, just process of elimination. Looks like you've located that the leak is on the outside of the firewall (if it was inside, the carpet would be wet and likely no puddle on floor). Check the connections at the master and slave cylinders (are they tight? Were the right fittings used?). Things leak from the top down. Run your finger under things, starting at the reservoir until you find it.
     
  8. massimofinance

    Nov 24, 2004
    39
    Put it up on the jacks. I am sure the puddles under the car are from the fluid leaking through from the inside cockpit. The carpets are greasy in the drivers footwell. This is the second master cylinder I put in and this problem is happening again. Weird thing is I still have good peddle pressure. Could the steel rod on the peddle be adjusted incorrectly and the fluid is leaking out the master? The engine bay is clean. It's not the reservoir. Or the slave. Thanks.
     
  9. lancia

    lancia Formula Junior

    Jan 18, 2004
    578
    You should have a small amount of clutch pedal free-play, adjusted with the rod. The master-bore has only one open end and that end faces through the pedal box into the cabin. If the bore seal is leaking, it is going to be dripping into the cockpit. Have someone else operate the clutch and observe the pedal actuation rod against the master bore from under the instrument panel with mirror and flashlight. You will likely be able to see the drip around the boot of the master. I think the bore is just aluminum; you may wish to consider having it sleeved, new seals, instead of replacing again. You might get a better quality result?
     
  10. DWR46

    DWR46 Formula 3
    Honorary

    Jun 19, 2012
    2,046
    You will be better off having an existing cylinder sleeved in brass. If done by a competent shop, your problem should be solved. Be aware that there are TWO different "free plays" at the pedal.

    1. Free play between the push rod and the master cylinder. This should be as little as 1/4" of pedal movement. Just enough to make sure the master piston fully returns when you have no pressure on the pedal.

    2.Free Pedal at the throwout bearing. This should be about 3/4" of pedal movement.

    So first you should feel a small amount of "free" movement till the pushrod contacts the master piston and then you should have additional "free" movement until the TO Bearing contacts the pressure plate.
     
  11. massimofinance

    Nov 24, 2004
    39
    Thanks to all that responded to date. I pushed the peddle in while looking at the pin enter the master and sure enough fluid is seeping out of the master, past that rubber grommet in which the push pin enters. I can remove it and have it sleeved in brass (anyone recommend a good send away shop?) but I really am confused why this happened with two separate master cylinders. Both were older stock. Never had this issue on my 330 GTC. Could it be the fluid I am using is bad? I use car quest heavy duty brake fluid dot 3. Yes, the free play on the pin is about 1/4. Thanks.
     

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