Hello, My name is Thomas and I have and am having fun with a 1992 D250, 5.9 2wheel drive, 168,000 mi..
I have contacted you because you seem very electric system knowledgeable. Diagnosing is important.I have read "just when I thought my brakes were good to go " by bigragu.
I am having brake problems. The brake pedal goes down when pushed, like at a stop light. It stabilizes "somewhat" about 1" from the floor. The brake light and ABS dash light have been on for a year. Decided to do front pads and rear shoes.
Working alone. Got the rear axle on stands, pulled L rim and axle in the rain. No 2 9/16" socket to remove drum. Reinstalled between rains.
Started truck, put in drive, pressed pedal , L rear wheel stops.
Front pads showed slight wear after 20,000 mi. Installed new front pads.
Bled all wheel cylinders once, well. (in intermittent rain). Still soft, sinking pedal.
Removed the balance valve wire (rain). Dash warning lights went out. Reconnected wire, lights back on.
In the bigragu post: "If disconnecting the balance valve shuts out the light, the MC is bad. (assuming you don't have a puddle of brake fluid somewhere)"
Is the MC definitely bad. It is pushing brake fluid out the top after I pump the pedal. Any recommendations on a Quality new or rebuilt (ordered one from O'Reilly, maybe questionable rebuilders?)
Thank You All

 

I would recommend that you carefully read that thread and understand what is being said. The problem that you are having is common and has been discussed a lot. The problem is probably related to adjustment issues, but could just as easily be the master cylinder...Mark

 

Thnx for referring to my post. The guys who assisted me on there were great. If you are working by yourself you can do one of two things- get a patient, very patient, assistant, or do what I did (cause getting an assistant was not an option) and order the brake pedal holder from orileys. It is a Lyle product part number LIS21520 thru O'Rileys. That is on page 60 of their catalog. Ask them to match Summits price, which is cheaper. They should have it in their store next day ship. Now use that tool to be your assistant. When bleeding the rears, have one bleeder up front cracked open and tubed into a clear container with brake fluid just as you would with the rears. Your pedal will depress further that way. It also helped that I changed my bleeders out to speed bleeders with the one way check valve built in. Crack the rear drivers side and one of the fronts, pump 2-3 times, hold down, slip the depressor tool on(held down and propped to the steering wheel) and go close bleeder at rear and front. If you are air free, the 1/4" tubing will show all fluid with no bubbles between the bleeder and the container that the tube goes into. Make sure your tubing goes up above the bleeder and down to the container to create this loop as NJT suggested. Then after the front and rear bleeders are closed, remove pedal depressor tool to allow brake pedal to rise up. Keep checking the master cylinder for fluid level and never allow it to lose fluid by emptying out, or you'll introduce air into your system. Follow this procedure for the other bleeders. When you think you have all the air gone, do it again. When I finally got it I ended up going thru these steps at least 5x a bleeder. Try all this 1st before swapping out your MC. use fresh brake fluid. I bought 3 quarts of O'Rileys DOT 3 synthetic fluid and went thru 2 and a 1/4 of the 3 quarts to flush and bleed my system. Also, before any bleeding is to be done, adjust your rear shoes to be tight to the drums(parking brake off). When you are good and air free, then adjust to slight to no drag. If you followed this to a tee and still no brakes then I would change out the MC. Unless of course you want to just put a new one in, change out the MC first then follow my steps. Don't get an O'Rileys MC; Mark suggests a Bendix(new) if you can find one. I returned my lifetime warranty Raybestos to NAPA in exchange for a NEW one. I've returned my Raybestos MC 3x already and got a NEW one every time, no questions asked. I will pm you with my contact info if you want to call me for more questions