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Leaking Master Cylinder?

Last post 06-06-2009, 8:12 AM by enfoprefect. 88 replies.
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  •  04-08-2007, 12:54 PM 6010 in reply to 5970

    Re: Leaking Master Cylinder?

    Zach-

    How funny is that!?! That's close to what I described happening with my Mustang.  The OLD switch was BAD- the NEW switch is GOOD. Its telling you there is a problem with the pressure on one side of the brake system by causing the light to come on! We already know there is a problem. That phrase... Butchered... gives us an idea of the quality of mechanics that came before you. Well, thats one problem solved.

    This does not eliminate  any other possibilities for the problem in the system all  the way from the new master cylinder to the caliper on that side of the system as far as I can see.

    Maybe I missed it but have you described how the brakes worked prior to replacing the master cylinder? It might give us a clue. 

  •  04-08-2007, 5:53 PM 6025 in reply to 6010

    Re: Leaking Master Cylinder?

    Brakes were good, except that the pedal was slowing going to the floor. Replaced the master cylinder and hoses and it fixed that.  Then I started to have the problem with the right front. 
  •  04-09-2007, 1:18 PM 6044 in reply to 6025

    Re: Leaking Master Cylinder?

    Zach-

    This is what I'd do at this point. And I want to say I can really appreciate all the work you've done so far and the patience and perserverance it's taken so I will do my best not to send you on a wild goosechase. 

    What I would do is this:

    1) Disconnect the line for the front brakes from the master cylinder.

    2) Connect a long clear hose to it and place its end in a jam jar w/ alittle brake fluid in it like you are going to bleed brakes. Cover the top of the jar with some clean old rags.

    3) Connect another hose to the front caliper that sticks' bleed nipple.

    4)  Connect air supply to caliper hose. (If you don't have an air supply a bicycle pump will work)

    5) Open caliper bleed nipple and using it like a faucet by opening and closing it slightly, blow air through it backflushing it (CAREFULL ABOUT SPLASHING BRAKE FLUID ALL OVER THE PLACE AT THE MASTER CYLINDER END!!!!) 

    6) Do this until only air comes out and make sure the air flows with no resistance-none at all.

    7) Check the contents of the jam jar.The brake fluid will have a ton of bubbles in it so you might want to wait for them to dissipate. You will be looking for any kind of debris (A POLITE TERM) that has dislodged hopefully clearing the mystery check valve out of the line. 

     
    Once you have done the above procedure you will have (In my opinion) eliminated anything from thatend of the line out to the wheel as the problem 

    Re-install the good pressure warning switch and the brake line and re- bleed the brakes using the Emmy Award Winning "Mr. MOTORBILL" method described above. Centralize the pressure warning switch as described in the manual and may God smile down upon thee!  AMEN!

    If you still have a problem at this point it has got to be the new master cylinder.

    The brakes worked fine prior to installing it with the exception of the leaking....Don't forget that!

    Before doing any work let's wait for feedback from Motorbill et al.

    LCJUTILA 

  •  04-10-2007, 2:42 AM 6068 in reply to 6044

    Re: Leaking Master Cylinder?

    Centering the piston.  Of course, there were no instructions with the Master Brake Cylinder that I received from Moss, and it appeared to be such a simple install that I didn't use the manual.  Could this have anything to do with my problems other than the brake pressure warning switch?

    zach

  •  04-10-2007, 8:45 AM 6072 in reply to 6068

    Re: Leaking Master Cylinder?

    The pressure warning switch will detect differences in the front and rear line systems, but will not, by its very, design actually affect them. That said, I'm not looking at the application on THIS CAR. As I've said before, there is a lot about this car we do know, but there is obviously something we don't know which is flogging us mercilessly.
    Motorbill
    From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon
  •  04-10-2007, 9:17 AM 6073 in reply to 6072

    Re: Leaking Master Cylinder?

    Zach-

    I agree with Motorbill about the pressure switch. On further consideration about my idea I think it might be prudent to backflush BOTH front brake lines from the calipers back to the master cylinder. It wouldn't be that much more work.There is a possibility that the problem lies in the left line. There could be an  intermittent obstruction in  the left side that causes a disproportionate amount of pressure to be transferred to the right side causing the right to lock.

    Anyway, for the slight extra work to do it we would eliminate one more thing and it seems unfortunately that this is turning out to be a long process of elimination.

    I HATE working on brakes but they are THE MOST IMPORTANT THING ON THE CAR! 

    LCJUTILA 

  •  04-10-2007, 2:33 PM 6082 in reply to 6073

    Re: Leaking Master Cylinder?

    Zach-

    What do employees and car parts have in common?........... 

     

    They don't do what you expect,  they do what you INSPECT!!!

    If it were any other part on the car and you said "Before I installed it everything was fine except it didn't work quite as well as I liked so I replaced the part and now I have more problems."  What part do you really think would have caused all the additional problems?

    The part you just replaced! Right?  I'm going to say it... The master cylinder.

    I'm not saying the other parts weren't due for replacement too, I'm just saying your problems didn't really start until you replaced the master cylinder

    Anyway, you've come this far so do the blowing out of the lines as I described, re-bleed the brakes, centralize that switch and see if that solves it.If it doesn't then it looks more and more like the master cylinder is the problem.

    The only other component that hasn't been discussed is a brake proportioning valve and I don't know if your car has one. 

    I used to be in the biz and motorbill still is and the worst feeling for guys who run a decent shop is to keep having a car come back and keep spending the customer's money replacing parts without solving the problem .

    If the master cylinder is bad it is no reflection on the supplier.  Sometimes they just are.

    LCJUTILA 

  •  04-10-2007, 6:45 PM 6096 in reply to 6082

    Re: Leaking Master Cylinder?

    Blew out the front lines and there was nothing but brake fluid in them.  My helper took my daughters to the movies and I wasn't able to get them bled.  Tomorrow night is taken, so it will probably be Thursday before I can get back to them.  Will let you know what happens.

    zach

  •  04-16-2007, 7:32 PM 6258 in reply to 6072

    Re: Leaking Master Cylinder?

    One of my brake calipers is leaking. Won't have a replacement until Wednesday.

    Lightning

  •  04-17-2007, 8:56 PM 6281 in reply to 6258

    Re: Leaking Master Cylinder?

    Ding Dang Diddly!

    Nothing but blue skies!

    Hang in there!

    LCJUTILA 

  •  04-20-2007, 5:53 PM 6335 in reply to 6281

    Re: Leaking Master Cylinder?

    Motorbill and LCJUTILA,

    Latest developments:

    Finally received a replacement caliper from Car Quest.  Put the top down (just to be prepared for the test drive), installed the caliper, adjusted the rear brakes tight until they wouldn't rotate, bled the system and centralized the switch in the master cylinder so that the BRAKE light now stays off, and backed off the adjustment on the back brakes one click.  Took her out for a test drive in the development.  It's a fairly small one, but being in Kentucky there are a lot of hills so the brakes got a good workout.  Drove around for about 10 minutes, braking a lot, and at one point about 5 minutes into the test drive, the right front brake pulled to the right and I thought the problem was back.  I drove back to the house and checked the wheels and they were a little warm, but not hot.  Continued the test drive around the development, but since things were going well, I went out onto a back road and got up to about 40.  Drove a couple of miles and pulled off to turn around and all was fine.  Drove back to the house and no problems.  I'm almost afraid to say that the problem has vanished!  Tomorrow, I'm supposed to help a family move, so I'll take the MG and see how she does.  Let's all cross our fingers!

    zach

  •  04-21-2007, 9:53 AM 6339 in reply to 6335

    Re: Leaking Master Cylinder?

    Zach-

    You have the essential ingredient to be an exceptional car mechanic...Tenacity.

    Congratulations

    LCJUTILA 

  •  04-21-2007, 1:45 PM 6344 in reply to 6339

    Re: Leaking Master Cylinder?

    Motorbill and LCJUTILA,

    Thank you, Motorbill, for hanging in there with me and LCJUTILA, although you came in at the end, you provided words of encouragement. I drove the old girl almost 80 miles today, up and down Kentucky hills and backroads.  The sky was blue, the sun was shining, and the temperature about 72 degrees.  She ran fine, the brakes never overheated, grabbed,or locked up, and I think the problem is resolved. What a great day.

    zach

  •  04-21-2007, 3:54 PM 6346 in reply to 6344

    Re: Leaking Master Cylinder?

    And thank you zachmg77 for keeping us informed. We all learned a lot and had some laughs along the way. Ken the poolboy.Yes
  •  04-23-2007, 11:47 AM 6371 in reply to 6346

    Re: Leaking Master Cylinder?

    zach,

    I was out of town this weekend giving a vintage racer with a TR4 a hand at the first event of his season, so I was away from the forum. WELL, persistence has finally paid some dividends. I'm extremely happy for you! Enjoy the fruits of your labors.

    It's interesting that you had a brand new (rebuilt) bad caliper. I'm afraid that we've been finding poor quality kits on yhe market in the past year or so and have seen a number of leaking calipers lately, whereas in the past they were almost unheard of. The very early Dunlop caliper/piston assemblies used to leak a lot, but they were a very primative design. The Girling type calipers were bulletproof. We really only used to rebuild them when they would start to drag or seize up. But rarely did they leak. I'm somewhat concerned by this trend and I intend to investigate.

    However, It's a great day for your MGB, and I hope there are many more to follow. Don't be a stranger now that you are up and running.


    Motorbill
    From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon
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