Sudden brake failure

Discussion in '365 GT4 2+2/400/412' started by Temerian, Jun 26, 2017.

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  1. Temerian

    Temerian Karting
    Silver Subscribed

    Jun 17, 2014
    87
    Manhattan
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    Rick Temerian
    While driving yesterday the brake pedal unexpectedly went down to the floor when pressure was applied. I could get the brakes to work poorly if I vigorously pumped the pedal. I managed to limp home. Where should I look first? The reservoir is completely full. I checked the vacuum hoses where I could access them from above and all look ok. I would like to get the brakes working even a little bit to drive to the mechanic and save the tow fees. Any suggestions?
     
  2. Ewan

    Ewan Karting

    Jul 5, 2015
    80
    Dorset, UK
    I wouldn't risk driving it with inefficient brakes. Even a low speed crash would cost more in repairs than the fees for a tow. And if a child ran out in front you suddenly...
     
  3. SAFE4NOW

    SAFE4NOW F1 Rookie
    Sponsor

    Aug 25, 2004
    2,958
    Dallas Texas
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    Steve F
    Brake Booster
    Master Cyl
    Fluid leaking from any of the brake calipers themselves?

    The risk vs the reward isn't worth it IMO, you don't know what you don't know and a transporter will be way less than an insurance claim.

    Please be careful!

    S
     
  4. Temerian

    Temerian Karting
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    You are right, Ewan. It's probably not worth the risk. I thought there might be a simple fix.
     
  5. Jasonberkeley

    Jasonberkeley Karting

    Apr 23, 2017
    143
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    Jason Berkeley
    Definitely check for leaks at each caliper and inspect all lines, hoses, etc...

    If fluid level is good and no leaks, a seal may have failed in your master cylinder.
     
  6. Part Time

    Part Time Formula Junior
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    Dec 16, 2013
    256
    Port St. Lucie, Fl
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    Gary Shore
    Rick....first, it's not worth the risk...call a flatbed truck. OK ?

    Second...The brake system is a "closed" hydraulic system, if you push the pedal down to the floor with no or little resistance, one of two things is at fault.

    Either you are "pumping" brake fluid out on the floor thru a leaking hose, pipe or caliper seal.....(but you say there is no change in the fluid level at the reservoir).....or.....you are "bypassing" fluid from the compression chamber in the master cylinder past a split or broken seal, to behind the seal where the fluid can return to the reservoir.
    If you were seeing the reservoir fluid go down, I would also check the joint between the reservoir & the m/cylinder for leakage, or even the carpet inside since it is possible to have fluid leak thru the booster also.

    It sounds like your master cylinder is at fault, if it is not scored or scratched inside, it can be easily rebuilt.

    Gary

    PS: I already have a kit here for mine, full brake job is on my list of things to do.
     
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  8. Al Campbell

    Al Campbell Formula Junior
    Silver Subscribed Owner

    Nov 22, 2013
    309
    Australia
    It should have a dual circuit to every wheel so that if something fails you still have braking on every wheel. If you have lost both circuits I would suspect the master cylinder has had moisture in it for some time and the whole system will need an overhaul.
     
  9. GT Jones

    GT Jones Formula Junior
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    Oct 15, 2011
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    Correct, Al. The system is a true dual circuit. I agree that its the master cylinder not building pressure.
     
  10. Jasonberkeley

    Jasonberkeley Karting

    Apr 23, 2017
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    Jason Berkeley
    So what was the verdict on the failure?
     
  11. Temerian

    Temerian Karting
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    Jun 17, 2014
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    A vacuum hose rupture. Replaced the hose and it's working fine. I'm going to replace all the belts and hoses now just to reduce the number of things that can fail.
     
  12. Al Campbell

    Al Campbell Formula Junior
    Silver Subscribed Owner

    Nov 22, 2013
    309
    Australia
    A leaking vacuum hose will cause the brake pedal to be very hard to push in but cannot cause the symptoms you described. I hope you don't find out the hard way that this was not the cause of the pedal going to the floor.
     
  13. Newman

    Newman F1 World Champ
    Professional Ferrari Technician Consultant Owner

    Dec 26, 2001
    12,310
    Barrie, ON, Canada
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    Newman
    Correct. Could be a bad master cylinder.
     
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  15. Temerian

    Temerian Karting
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    You are correct, Al. I mis-described the symptoms. The pedal was super hard to push but it would stop the car.
     
  16. kevfla

    kevfla Formula 3

    Nov 20, 2003
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    orlando, fl
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    kevin flankey
    If the system is similar to my Rolls ('67 Shadow), there is no "master cylinder" or vacuum brake booster.
     
  17. Jasonberkeley

    Jasonberkeley Karting

    Apr 23, 2017
    143
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    Jason Berkeley
    Glad you found it and a simple fix. Good call on replacing the other stuff!
     
  18. It's Ross

    It's Ross Formula 3

    Jul 30, 2007
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    Ross
    This post made me curious so I investigated. Good Lord, talk about needless complication.
     
  19. OttoB

    OttoB Formula Junior
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    Aug 17, 2013
    504
    Palm Beach, FL
    Back in 1994 when I bought a 1985 Maserati Biturbo while I was still only 20 years old, I joined AAA before going to pick it up. 23 years later, I am still a member. For like $75-$90.00 per year on the gold membership, you have up to 4 tows per year, up to 100 miles each! Throughout the years, I will run out of my 4, and then get a card for the ex to use up her allotted tows at whatever price the membership comes out pro rata 6+ plus months in.

    Trust me, its worth it. I just used my 3rd tow on Friday as of March and have peace of mind.
     
  20. 166&456

    166&456 Formula 3

    Jul 13, 2010
    1,715
    Amsterdam
    A vacuum failure is unnerving, a failed master is nerve wrecking. I experienced both (yes on a dual system) and ever since I have a master overhaul on every car's maintenance list (apart from 36 month maximum fluid changes).
    One overhaul or replacement every two decades or so costs peanuts and believe me, it's very much worth it.
     
  21. It's Ross

    It's Ross Formula 3

    Jul 30, 2007
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  22. Temerian

    Temerian Karting
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    Some bad news. Going through the coolant system we found engine oil in the radiator.
    Looks like I'm going to have to pull the motor. Any advice other than expect to spend a lot of money?
     
  23. 166&456

    166&456 Formula 3

    Jul 13, 2010
    1,715
    Amsterdam
    Are you positively sure the PO did not accidentally put oil in there? You may laugh but this recently happened to a friend who has three decades of car experience, pouring from a can of used oil rather than coolant.
    Other than that it could be a heat exchanger or head gasket issue. I don't believe these have oil-coolant heat exchangers so that leaves a head gasket. Do check the specifications around cylinder head bolt torque specs, on older motors like this a head gasket needs to be retorqued after a few heat cycles. It could be this was done too late or not at all.
     
  24. 400iGuy

    400iGuy Formula Junior
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    Aug 26, 2004
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    Al
    It is possible for a failed water pump seal to allow oil into the cooling system. Don't have to remove the engine to rebuild the water pump. You just need a forearm and fingers with extra joints in them:)
     
  25. Ashman

    Ashman Two Time F1 World Champ
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    Sep 5, 2002
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    IITC there are two seals in the water pump but only one can be changed with the engine in the car. At least that is what the workshop manual said.

    For Temerian:

    The first thing you should check are the little o rings below the oil filter as they are a very common source of oil in the coolant for these engines. This is not a complicated or expensive fix and should be done before anything more drastic.

    WRXMike posted some description and photos with part numbers back in 2012 and also referenced other threads about the issue. Try a search "oil in coolant".

    OK, here it is:

    http://www.ferrarichat.com/forum/365-gt4-2-2-400-412/376670-oil-coolant.html
     
  26. 400iGuy

    400iGuy Formula Junior
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    Aug 26, 2004
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    That's a great recommendation. I forgot about them.
     
  27. Jasonberkeley

    Jasonberkeley Karting

    Apr 23, 2017
    143
    New York, NY
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    Jason Berkeley
    Great link and reference. Thanks for posting. Never knew this could be an issue. Hopefully this is all Temerian has to deal with.

    Im going to check my coolant this weekend.
     
  28. Ashman

    Ashman Two Time F1 World Champ
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    Sep 5, 2002
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    Yup, that was the source of the oil in my coolant. In the pantheon of things that can cause something like that, that was the least bad, but probably most common! :)

    PS: If you decide to do this yourself, keep very good track of which o ring goes where. As noted in the thread, they look almost identical to the naked eye once they are outside of their numbered envelope but they are not and switching them in position will not solve the problem. Ask me how I know! ;)
     

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