Rear brake line

I live in the salt covered roads of Wisconsin. I had a rear brake line blow out. I ran in to problems bleeding the brakes. I think I have it figured out. I thought I would share my experience, and see if anyone else has worked through this. The steel brake line to the rear brakes that runs along the drivers side frame rail had rusted out. The first thing I did was check the bleeders on wheel cylinders, also rusted beyond recognition. I pulled the drums off, and I had them turned. I replaced the shoes, springs, wheel cylinders rubber line on the rear end, and the steel lines. I then went to bleed the brakes and I never got the pedal to do anything but go to the floor. I changed the master cylinder. I suspect that there was old junk in the master cylinder that made it stick. I then was able to bleed the rear brakes and got some pedal back. I went to bleed the front brakes, and the front bleeders were permanently rusted shut. I got new calipers and pads, and while I was at it I decided to change the rotors, hub bearings, and front steel and rubber lines. Changing all that stuff may be a little over kill, but I did they looked to be half worn and I not want to take the same stuff apart multiple times to fix the same problem. I also do not want to be stuck far from home with bad brakes. Been there done that. I almost have it back together. I am hopeful this will be the last of my brake problems for a while.

1997 GMC K1500 Suburban 6.5T, Heath Turbo Controller, rebuilt turbo, Heath crossover pipe, relocate PMD. Everything else is stock for now.

Glad to see you're getting it worked out.

I do a good deal of my own work, but I'm not a mechanic, but let me take a stab at what happened and anyone feel free to correct me. During the process of changing the rear brake lines, lot's of air entered the system. Probably even made it into the fronts since the MC reservoir went low. So trying to bleed the brakes from the rear only, and then looking for the pedal to be firm isn't going to happen until all four corners are completely bled. Once all four wheels are bled, THEN the pedal should get firm. Am I on the right track?

You may be right. I could not bleed the front until I changed the calipers because the bleeders were rusted so bad. Since then I got it all together and tried to bleed it several times. It still must have air in the lines. The pedal is real spongy. I thought there may be air in the ABS. Twice I tried driving it and hitting the brakes real hard to get the ABS to cycle, then I bled it afterward. It did not make a difference. There is still an air bubble somewhere. I am not sure what else to do.

It’s been awhile since I looked it up, but I think you need a scan tool to get air out of the ABS unit. Not exactly clear on that since I haven’t had to do it. Typically you start at right rear, then left rear, right front, then left front.

I bled in that order, RR LR RF LF, many times. I read about the need for they Tech 2 tool to cycle the ABS, but i also read that you could do the same thing by driving, getting the ABS to kick in, and bleeding again. I have never bled the brakes in this model truck before. So far I am not having a whole lot of luck. Any advise would be appreciated.

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1997 K1500 Suburban 6.5T, PMD relocate, Heath crossover pipe, Heath turbo controller.

How are you bleeding the brakes? Two-person pump the pedal? Vacuum bleeder? Pressure bleeder?

I was bleeding using the two person method. I tried pumping the brakes, hold it, then briefly open the bleeder, close the bleeder, release the pedal. I also tried open the bleeder, push the pedal (do not pump) close the bleeder, release the pedal. The standard two person system did not do the trick. I tried these methods a lot of times. I'm am pretty sure there was a bubble high in the system, probably between the MC and ABS.

I fixed it now. I learned this trick in the Army. I have been out a few years and I only saw it used once, so I almost forgot about it. I tried it today and it worked. Happy Verens Day! Here is what I did.

I loosened the lines at the MC very slightly so they would drip a drop every three seconds or so. I loosened the MC cap. Then I let it drip for about 45 minutes. I caught the fluid in an old container. Total drip page was only a few tablespoons. The MC never went dry. After the wait I topped off the MC and tightened the lines, secured the cover. Now I have full brake pedal. Finally!