louie130309 Posted January 18, 2006 Share Posted January 18, 2006 So i was driving the other night and i decided to take my comanche down a little trail. I pulled into the trail and stopped to put it into 4wd and my brake light comes on ( emergency brake light, inside of truck) and my brakes go to the floor and have almost np pressure. So now i only have front brakes that barely work at all and my brake lights on. I checked the fluid which was a little bit low so i added some, but that didnt help. I'm going to bleed them later and see if it helps. If anyone has any ideas let me know. thanks Link to comment Share on other sites More sharing options...
mjeff87 Posted January 18, 2006 Share Posted January 18, 2006 You've lost pressure to the rear circuit somewhere. My guess is the rear brakeline back along the framerail, up in the corner right before it bends toward the rear height valve. Seems like all MJ's blow the line out somewhere right around there. Follow the hard lines along the framerail underneath back and look for fresh fluid splattered out. It may not be there (could be a wheel cylinder), but if it's in the line, your best bet is to not do a patch job, but cut the line back to clean solid metal and splice in there. I had to go almost back to the front LCA area to find solid enough line to fix mine :oops: If you just patch the bad section you may find, odds are it's gonna blow out somwhere else sooner than later. Jeff Link to comment Share on other sites More sharing options...
pingpong Posted January 18, 2006 Share Posted January 18, 2006 Ok I just redid my brake lines from front to back on my truggy. Seems that on the XJ proportioning valve, they block of the return port for the Hieght sensing valve. To me it would make more sense to replace the whole line while you are working on it. Patrick Link to comment Share on other sites More sharing options...
CWLONGSHOT Posted January 22, 2006 Share Posted January 22, 2006 Mine did the same last summer!! I ended up haveing to insatll the COMPLETE line from the front to the back....I tried or rather looked into just splicing in, but the more I looked the more bad line I found. You don't want to skimp here!!! REPLACE THE ENTIRE LINE!!! I chose to remove the idiotic rear proportioning valve and installed a XJ front prop valve in place of the MJ's distribution block. The rear valve was WAY rusted and I was unable to get any of the lines to come out. My brakes are better than ever!! Good luck, CW Link to comment Share on other sites More sharing options...
Eagle Posted January 22, 2006 Share Posted January 22, 2006 Ok I just redid my brake lines from front to back on my truggy. Seems that on the XJ proportioning valve, they block of the return port for the Hieght sensing valve. To me it would make more sense to replace the whole line while you are working on it. That's not a return port. On the MJ, one port sends fluid through the rear, height sensing proportioning valve. The other port bypasses the rear valve and allows full brake pressure to the rear circuit if the front circuit loses pressure. In theory. See the thread in which I posted a picture of an MJ valve cut in half to see why theory doesn't always work. Link to comment Share on other sites More sharing options...
Stumpy Posted January 22, 2006 Share Posted January 22, 2006 same thing happened on mine bout 2wks ago, after i fix that it'll be ready for the trails! woohoo!! 8) Link to comment Share on other sites More sharing options...
pingpong Posted January 22, 2006 Share Posted January 22, 2006 Eagle, I looked at the XJ valve I used, after I removed the one off of my trail rig, and it had the same part number on it. The only difference was the plugged line hole. That is why I said what I said. Patrick Link to comment Share on other sites More sharing options...
louie130309 Posted January 22, 2006 Author Share Posted January 22, 2006 well i ended up replacing about 6 brake lines, both wheel clyinders in the back, new brake shoes and resurfaced the drums Link to comment Share on other sites More sharing options...
Stumpy Posted January 23, 2006 Share Posted January 23, 2006 checked out my rear lines and found the problem was the line goin to the height sensor that blew so i took the sensor assm out and i'm gonna plug the valve where it was and the one on the front this week so i'll hopefully be ready to "stop" again...lol Link to comment Share on other sites More sharing options...
CWLONGSHOT Posted January 24, 2006 Share Posted January 24, 2006 well i ended up replacing about 6 brake lines, both wheel clyinders in the back, new brake shoes and resurfaced the drums You will be GLAD you went the extra distance, the first time you have a panic stop!! GOOD JOB!! CW Link to comment Share on other sites More sharing options...
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