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348 Clutch pedal going limp

Discussion in '348/355' started by Fguy, Apr 18, 2022.

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  1. Fguy

    Fguy Karting

    Oct 4, 2011
    69
    Sarasota, Fl
    Full Name:
    Julian Angus
    #1 Fguy, Apr 18, 2022
    The clutch pedal on my 1990 348 went limp while in my garage (how lucky!). I have checked under the car for leaks and so far there are none. The throwout bearing and seals were successfully replaced with the Hill Engineering set about 4 years ago. What are the chances that the problem is simply related to the clutch master cylinder? Any ideas? The part is available (new and used) from different sources and other than the difficulty in bleeding the system, it looks like an easy job to replace. Thanks for your response.
     
  2. 26street

    26street Formula Junior

    Jan 30, 2021
    437
    Westchester New York
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    Mark k
    #2 26street, Apr 18, 2022
    Wow lucky it happened in the garage
    Sounds like the seals if no signs of leaking anywhere —- either the master cylinder or slave cylinder let go internally

    Does it even try to build press if you pump it ???
    There’s a few ways of check both items chances are it’s the master but still check both



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  3. Fguy

    Fguy Karting

    Oct 4, 2011
    69
    Sarasota, Fl
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    Julian Angus
    #3 Fguy, Apr 18, 2022
    No pressure build up. Pedal goes all the way to the floor. Fluid reservoir remains full. Any other ideas?
     
  4. 26street

    26street Formula Junior

    Jan 30, 2021
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    Westchester New York
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    Mark k
    #4 26street, Apr 18, 2022
    As long as the push rod from pedal to master is there then Sound more like the master cylinder—-easy replacement I would bench bleed the new one before installing and the bleed both master and slave after installing


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  5. John Glen

    John Glen Formula Junior

    Dec 30, 2009
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    Victoria, B.C, Can.
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    John Glen Wesanko
    #5 John Glen, Apr 18, 2022
    I have the same 90 348ts and had issues bleeding the clutch after having the engine out to do maint. The clutch master seems to get air locked easily. I already had the trunk liner out and managed to finally get back some pressure after l removed the flex line coming out of the clutch master and had an assistant pump the pedal. Once I had pressure at the outlet port I reconnected the braided hose and proceeded to successfully bleed the system from the pumpkin. Note: (put a towel around area to catch fluid) Also found the plastic vent tube from the reservoir cap was blocked somewhere down below, not helping .... Or you could need a new master ?
     
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  6. Fguy

    Fguy Karting

    Oct 4, 2011
    69
    Sarasota, Fl
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    Julian Angus
    #6 Fguy, Apr 18, 2022
    Great info. I already have the liner out for easy access. I will try and disconnect the flex line and see if I can build pressure. Thank you.
     
  7. Mike Morrissey

    Mike Morrissey Formula 3
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    #7 Mike Morrissey, Apr 18, 2022
    I replaced my clutch master cylinder about a month ago, F355, mine was leaking. 175211 Clutch Master Cylinder, Eurospares, Brembo $172.72, was the best price I found. I bench bled the new one, to no avail. I had success by attaching a Motive pressure bleeder to the Reservoir while bleeding at the pumpkin with the pedal depressed.
    This got me 90% close. The next step was to leave the cap off of the reservoir, fully depress the clutch pedal and bleed once more.
     
  8. Fguy

    Fguy Karting

    Oct 4, 2011
    69
    Sarasota, Fl
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    Julian Angus
    #8 Fguy, Apr 19, 2022
    Is it possible to disconnect the pressure line and block output port and then see if it builds pedal resistance?
     
  9. Mike Morrissey

    Mike Morrissey Formula 3
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    #9 Mike Morrissey, Apr 19, 2022
    I haven’t tried that, but I’ve read that it’s is a good test for the condition of the master cylinder seals.
     
  10. John Glen

    John Glen Formula Junior

    Dec 30, 2009
    493
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    #10 John Glen, Apr 19, 2022
    Once the braided ss flex line is unscrewed I just held my finger over the port to sense the pressure when pedal is activated.
     
  11. Fguy

    Fguy Karting

    Oct 4, 2011
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    Sarasota, Fl
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    Julian Angus
    #11 Fguy, Apr 19, 2022
    Sounds like a good method. Hopefully I will find no pressure; that will make it an easy repair job and will not have to look some where else. Thank you.
     
  12. Ferrarium

    Ferrarium F1 Veteran
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    Jul 28, 2018
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    #12 Ferrarium, Apr 19, 2022
    if you did the Hill TOB in all probability its the master cylinder seals. They are old....
     
  13. Fguy

    Fguy Karting

    Oct 4, 2011
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    Sarasota, Fl
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    Julian Angus
    #13 Fguy, Apr 20, 2022
    It must be the original; it still shows yellow paint on the mounting studs. Thank you.
     

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