I think there is air in the ABS block. Everything has been bled several times, but the truck still takes a while to stop. How is the ABS block bled? I find now that my stopping distance is variable, but it still takes a while to stop. It is a little better than before, though. The pedal goes down about 1-2 inches then stops like 1/2" above the gas pedal at idle. Pushing the pedal down to where it stops is the only way to get braking action. It is basically all or nothing. It sometimes goes down to the level on the gas pedal rarely on the first application after startup, but not to the floor or anything like that. The remaining hoses seem fine. No overheated brakes. I think the problem is actually under the hood. It seems that the brakes are only getting applied a little bit, but the pedal isn't abnormal. Is there a chance that the master cylinder was replaced improperly 2 months ago? Is that something that can be messed up?

 

I am not sure if you can bleed the abs block, someone can chime in if you know you can. I have only bled the brakes at the calipers or drums. I am sure tho that if you keep bleeding the front drivers side caliper and or passenger side that the air if any should be pushed thru the abs block and out either caliper, maybe a vacuum bleeder pump may help. As far as the master there is not much that can go wrong with replacing that other than you could get a faulty one, I am pretty sure a master can be bled but have never done it so I am not sure exactly how. I will look today on the master on my blazer and look for bleeders on my abs block and master and get back to ya tonight when I get home from my parents.
On my blazer I get brakeing at like 1/2 inch down on the pedal and good braking at like 1 inch down, if I tried to go down as far as you do I would have brake lock up and abs activation

 

http://www.aa1car.com/library/abs_kelseyhayes.htm

I found this. It says that if a pressure bleeder is used, the combination valve must be open.

"If air has entered the lines, it may be necessary to bleed the modulator, then the brake lines, then the modulator again to remove all trapped air. A modulator bleeder screw is provided on older applications, but the screw was eliminated on some of the newer applications. For these, it may be necessary to loosen a brake line at the modulator to vent bubbles from the modulator."

I think I found the problem. I even went to the GMC dealership 2 months ago just after the brakes failed twice originally and had the brakes flushed. I asked them about the ABS block and they said that there was no special bleeding procedure for that.

I couldn't find any valves on the master cylinder. The only thing there are the 2 brake lines. I can't really tell what is what on the ABS block. Too bad I can't pay someone to remove the ABS block, put a proportioning valve in for the front brakes and then extend the line for the rear brakes directly to the master cylinder. I wonder if something is electrically wrong with it like a valve being held open. I wonder what would happen if I were to pull the ABS fuse.

 

Looked at mine also and there is no bleeder on the abs block, so you would have to bleed by just loosening the lines on the abs block and let air escape that way.... same for the master... if there was anything wrong with the abs then you would get a abs light if it was operating incorrectly. I would start bleeding at the master and then go to the abs block, then do both front calipers and then the rear calipers, then go back and bleed the abs block one last time.. make sure to keep the master full of fluid

 

I dropped the truck off this morning. The mechanic found nothing wrong with the truck. He even made hard stops with it. He even said the pedal feels normal and no different from any S-10 pedal he has ever pressed. What is so funny is that the truck was stopping 100% better after I picked it up from the mechanic. I washed the truck afterwards and it went back to what it was, but then after about 2 miles of driving and braking, it improved dramatically. I was able to make much better stops. I called the mechanic after I picked it up and told him "I don't know what you did, but it is stopping 100% better". He said he can tell there is no air in the ABS or anywhere in the system. He said that it is possible that the brake pads weren't seated properly since the rotors weren't replaced at the same time and they fixed themselves. I hope it stays this way or improves and doesn't go back to the way it was. It seems like that they work better when they are hot.

 

Glad its fixed!! Maybe it needed a couple hard stops, but I never heard of having to do anything like that, of course I have front disk and rear drum, never had to do that after replacing front rotors and pads but I also do them at the same time so what the mechanic said might be true.

 

Maybe it did, but now it takes a few stops before the brakes start to work correctly. If the truck sits for a while, it takes a long time to stop, then after the brakes heat up, the truck stops on a dime. Otherwise, the truck stops fine.

 

Is it possible my rotors are bad? When they get hot, they expand and then they work well? Is there a chance they are warped? I had my wheel bearings replaced in March. Is there a chance they were rubbing, overheating and getting warped? I was looking at the Wearever rotors at Advance which are around $35 or the Napa Premium ones which are only $29. Are those good?

 

Usually a good way to tell if your rotors are warped is if your brake pedal pulsates while you are braking, the Napa premium rotors are pretty good, I usually stay away from anything Advance sells since I have had a number of bad products from them before, I stick with Napa or Oreilly auto. Is your pedal pulsating while you brake?

 

Ok thanks for the tip. I agree 100% with most of Advance's Parts. I'll go with Napa. There is no pulsation. It just feels like the calipers aren't grabbing the rotors well. Basically it just feels like there is water or oil on the brake rotors. I can hit the brakes and the braking action will decrease as the truck slows down and the truck takes a while to slow down. The pedal is firm and the mechanic said the pedal is fine as I said before. He said there is no air in the system. Sometimes I hear a squeal, most of the time it is quiet. Should I get new rotors? Could that be the probable cause?