STERLING STINGER Posted March 2, 2010 Share Posted March 2, 2010 my 92 just lost its brakes i just drove it like 9 miles with barley anything...to the floor! scarry :rant: i see no fluid leaking anywhere they go to the floor when the truck is off, i can pump them and they feel tight but as soon as i start it, back to the floor replace master? pick n pull upgrades? Link to comment Share on other sites More sharing options...
Pete M Posted March 2, 2010 Share Posted March 2, 2010 when you figure it out, let me know. :thumbsup: my 88 suffers from the same thing. Link to comment Share on other sites More sharing options...
STERLING STINGER Posted March 2, 2010 Author Share Posted March 2, 2010 you drive it like that? Link to comment Share on other sites More sharing options...
smithe1811 Posted March 2, 2010 Share Posted March 2, 2010 Bad Booster? sounds like its time to make the upgrade to the dual diaphragm one. Link to comment Share on other sites More sharing options...
james750 Posted March 2, 2010 Share Posted March 2, 2010 sounds like a booster problem. check your fluid level, pad wear, wheel cylinders, and calipers, as well as all the lines and valves. Do you hear a hissing coming from your booster with the truck on and the pedal not being pressed. Link to comment Share on other sites More sharing options...
Pete M Posted March 2, 2010 Share Posted March 2, 2010 sounds like its time to make the upgrade to the dual diaphragm one. That's my plan, and the reason I didn't investigate further. No hissing sound from mine. you drive it like that? Heck no. The 88 doesn't really go anywhere. Even more so now that the gas tank won't hold gas. :( Link to comment Share on other sites More sharing options...
Backroads Posted March 2, 2010 Share Posted March 2, 2010 I'm gonna say its the master cylinder, and possibly the booster as well. I had another vehicle, same thing. I would bleed the brakes and have a nice firm pedal, but once the engine was running it would sink to the floor. If you pumped it a few times quick, it would build a little pressure, but was instantly gone. Someone then told me, when you bleed brakes on an older car/truck, to put something under the brake pedal so that when you are pressing the pedal you arent bottoming it out. Over time you will wear a 'groove' for lack of a better word, on the shaft of the MC. When you bleed the brakes and or lose brakes and the pedal bottoms out, you mess up that seal and it then leaks and will not hold pressure. Either way on the other car, once I put in a new MC, brakes worked like new! Link to comment Share on other sites More sharing options...
STERLING STINGER Posted March 2, 2010 Author Share Posted March 2, 2010 booster? the big black round thing behind the mc? what grand cherokee can iget one from for an upgrade? or evena replacement....bolt in Link to comment Share on other sites More sharing options...
smithe1811 Posted March 2, 2010 Share Posted March 2, 2010 Do i smell another D's trip this weekend? :brows: Link to comment Share on other sites More sharing options...
STERLING STINGER Posted March 2, 2010 Author Share Posted March 2, 2010 like tomorrow Link to comment Share on other sites More sharing options...
Eagle Posted March 2, 2010 Share Posted March 2, 2010 One of my NAXJA friends had this with an '89 XJ. He replaced just about everything in the system, with zero improvement. What finally fixed it was removing the factory proportioning valve and replacing it with an adjustable proportioning valve. However, I recognize that the MJ does not have a proportioning feature in the front metering block. So some diagnosis is in order. Back to basics: Have you removed the cover from the master cylinder to see if one or the other chamber is low -- or empty? That's the first step. The large chamber feeds the front brakes, the small chamber feeds the rear brakes. Check it out and let us know. Link to comment Share on other sites More sharing options...
STERLING STINGER Posted March 2, 2010 Author Share Posted March 2, 2010 :dunno: they were both a little low when i opened it i filled it to the top, put cover back on, then pumped with engine off pressure started truck.. to the floor :fs1: i took the cap back off and they were both full i pumped with cover off and there were bubbles in the front chamber when the pedal was coming UP does that help a little more? Link to comment Share on other sites More sharing options...
STERLING STINGER Posted March 2, 2010 Author Share Posted March 2, 2010 sounds like a booster problem. check your fluid level, pad wear, wheel cylinders, and calipers, as well as all the lines and valves. Do you hear a hissing coming from your booster with the truck on and the pedal not being pressed. i hear hissing from the booster with the truck off and pressing the pedal down...then the bubbles inthe front chamber when pedal is coming up Link to comment Share on other sites More sharing options...
STERLING STINGER Posted March 2, 2010 Author Share Posted March 2, 2010 update... just woke up, :chillin: , and went into garage to look at my master... front chamber is full still rear is 100% empty! :eek: looked for leak on floor....hard to see cuz floor is wet from snow falling off trucks....didnt see anything! figured it disipated in the water on the floor. looks like i gotta track down a rear line leak, huh? i mine as well put that new brake block on too,(to bypass that crazy brake system in the rear)...... eric.....come up n help :D Link to comment Share on other sites More sharing options...
STERLING STINGER Posted March 2, 2010 Author Share Posted March 2, 2010 two chambers on my master cylender front one (small) = rear brakes? rear one (large) = front brakes? am i right? :shake: Link to comment Share on other sites More sharing options...
Eagle Posted March 2, 2010 Share Posted March 2, 2010 two chambers on my master cylenderfront one (small) = rear brakes? rear one (large) = front brakes? am i right? :shake: Yes, the large reservoir is for the front discs. If the small reservoir went empty, you have a leak. The most probably place is naturally the least accessible -- where the lines run along the frame above the fuel tank. Link to comment Share on other sites More sharing options...
STERLING STINGER Posted March 2, 2010 Author Share Posted March 2, 2010 thats where my last one was....sheesh onr thing happensd to one truck, then the other within a week....dang at least i know how 2 do it tho have to put this thread on hold for a day or 2 work truck lights are more important...(other thread) i appreciate all your help Link to comment Share on other sites More sharing options...
Backroads Posted March 3, 2010 Share Posted March 3, 2010 Just discovered the same problem with mine. It must have had a pinhole (of course where Eagle said, where the line runs between the gas tank and the bed wall) and I found a puddle that turned out to be brake fluid. SO now I'm midway to replacing the entire line from the MC back. Link to comment Share on other sites More sharing options...
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