1981 Jeep CJ7 no brakes

Tiny
JCHEDLEY
  • MEMBER
  • 1981 JEEP CJ7
  • 6 CYL
  • 4WD
  • MANUAL
  • 122,000 MILES
I have replaced pads, calipers, brake hoses, shoes, drums, wheel cyl, and hardwarew on the back brakes. I have blead brakes all kinds of combinations and also have went through 3 master cyl and a power brake booster. I have bench blead master cyl each time before installing on vehicle.
I hit pedal first time and it goes to floor, it will pump up after about six pumps. I have gone thru 10 quarts of dot 3&4. I can't seem to get the brakes to work properly, any suggestions please. Thank you in advance, Jim
Thursday, March 19th, 2009 AT 7:13 PM

5 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,052 POSTS
Is the push rod that goes to the rear of the master cylender adjustable? Also, when you pump them and get a pedal, will it hold or does it still go to the floor after some time? Also, when bleeding, start at the wheel the furthest from the master cylender (R rear) and work to the next closest and so on. It should be RR, LF, RF, LF.
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Thursday, March 19th, 2009 AT 8:56 PM
Tiny
JCHEDLEY
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I checked to see how far the stem pushes and it travels enough, it's not adjustable, When I pump the pedal, It will come up and hold untill you let it go. I have bleed the brakes like you suggested plenty of times and for the most, I don't see any air most of the time. This Jeep came to me with the same problem, inadequate brakes, the rear drums were turned to much by someone and shoes were about 50% I replaced everything incl hardware on the rear. Thz for your help, what are symptoms of a bad P-valve? Jim
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Thursday, March 19th, 2009 AT 9:19 PM
Tiny
JACOBANDNICKOLAS
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The P-valve limits the amount of pressure goes to the rear brakes. The proportioning valve only lets a certain portion of the pressure through to the rear wheels so that the front wheels apply more braking force. If it is bad, you may find that the rear brakes would lock up easier. It could also have an effect on the pedal. However they rarely go bad.

You did say the rubber brake hoses were replaced too. Are you sure they are not swelling when the brakes are applied due to a bad hose?

Because the system is sealed, like you I would have gone to the mastercylender. If nothing is leaking, the only thing left is the p-valve.
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Thursday, March 19th, 2009 AT 10:11 PM
Tiny
JCHEDLEY
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Thank you, I guess I will go ahead and change the proportioning valve. Jim
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Friday, March 20th, 2009 AT 5:13 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,052 POSTS
Let me know if it works.

Joe
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Friday, March 20th, 2009 AT 10:17 AM

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