I am working on a 2000 S10 4WD

Last Saturday my girl complained of squeaking. I checked front and rear and rear was down to the indicators. I replaced the pads, using caliper to push pistons back as always. She drove off happy.
Next day she said smell of brakes burning was there. Two days later she brought it to me and the rear brakes were locking up.
A quick Google check says common after pad replacement. Replace rear calipers. I did.
I bled all the air from them and now I have only half a pedal. I guarantee you I put 1 quart of fluid through each rear with no bubbles at all. I used a hose to a clear bottle with fluid so I could see after each bleeder crack. Still a fairly hard pedal when engine off and almost straight to the floor when engine started. The brake light also comes on and I stab the pedal to make it go off. Test drive reveals only about half a pedal. It will stop, but its not like it was. Something clearly amiss.

I have searched and read nearly every thread on this issue. Several guys have had the same problem. Some claim the ABS system has air and needs to be bled and reset with the "scan" tool. Well, I didn't get any air in the system ever from the front. The MC was never dry or low. I did bled the front after I started recognizing that I had a problem, no air. I've been bleeding for nearly 3 days now and used over 5 quarts of fluid. There is just no air. Clean fluid is seen from the hose in the bottle.
I've tried the pump 'em up method and the push down slow method. I've followed every "guide" for bleeding. One says to bled the front bleeder on the ABS unit, well no fluid comes from mine. I loosen it with a firm pressure on the pedal and nothing comes out. There is pressure to the inlet of the ABS unit. There is pressure on the outlet of the ABS unit(rear lines). I assume the rear bleeder is the one on the front of the ABS unit. Using a 3/4" wrench to turn it and has the little bleeder looking thing in the middle.
There was nothing wrong with this system except for the wear indicators squeaking.

Nothing makes any change to fairly hard pedal engine off and almost to floor when you start it. I drove the car to a gravel road and made the ABS activate. Still no change after.

What is wrong with my rear pad/caliper replacement and what do I do next?

Thanks,
Gary

 

I would take it to a shop that can put a vacuum bleeder machine on it.

 

I've considered that. But don't we believe our eyes? There is no air coming from the lines when I bled them. None. The system was never opened past the rear calipers. I'd like to examine something more logical, which frankly I don't see.
Thanks anyway.

 

I am leaning toward the Master Cylinder, I think the Mc is Bleeding back internal. Not running you have a firm peddle, but when you start the engine, It has the Vacuum boost and more pressure on it. Could it be when you pushed the fluid backwards it messed up a seal in the MC ? Just My thoughts on this matter. T.J.

 

Yeah, I thought of that but I have done the same procedure so many times I cant count. Take of the MC cap, push pistons back slowly with C clamp. Good to go. But I agree, it certainly has the qualities of a MC. I rule it our because it worked perfect before I put the pads on and I have used that same technique for so many years. It would surely be a fluke if that happened.
So you start figuring what could I replace? Well, I started with the RR caliper. Figuring that maybe one of the ones I got from the parts store could be bad. I did that. No change.
I figure I could change the MC but that would just be against logic as well.
The Power bled is 59.95. The one from a reservoir, not the one where they have to stop and fill the MC. I don't want that as it might let them introduce air to the ABS unit.
There's nothing left for me to do. I am stumped.
I figure power bled first in case there is some air somewhere, followed by MC, then I suppose I'll have to bite it and take it to someone that has the Tech 2 scanner and have them reset the ABS unit. God flippin knows what that is going to cost.

Let me add this. I've driven it for about 35 miles. You cant pump it up. Its just a low pedal. Basically there is no rear braking going on. The pedal goes low enough to activate the brake light. But if I stab it real quick, the light goes out. But I cant pump it up. Thast another reason I think there is no air in the lines. If I leave the car alone for 15mins or so, the pedal goes halfway to the floor with the engine off, then if I hit the pedal again, there is great resistance as if it is pumping up but it doesnt. Its just great ressistance until the front discs kick in and the pedal stops.

All for a simple brake job.. GD it.

Thanks for the suggestion.

This thread has a guy with the exact same issue. Exact. But he never comes back and says what fixed it. Scroll down to unicorn333. So my issue is not unique:
http://townhall-talk.edmunds.com/Web...Ptn@.f1cbf0b/0

 

Did you rotate the caliper cylinder when pushing it back in the replace the pads? Rears have a screw type adjuster for the parking brake that can be damaged by pusing them straight in without turning it. I've seen this cause all sorts of strange braking phenomenas! LOL

 

Not relevant for two reasons. I replaced the calipers. Then replaced one of them again just in case I got a new one that was bad.

In this Blazer, the parking brake system is not connected in any way to the discs. In fact you could remove the parking brake system entirely and it would have no effect on the operation of the discs'.

Thanks anyway, keep those thoughts coming for the next guy that reads this thread years down the road.

gary

 

I've had several GM disc brake cars that experienced failure of the flexible brake fluid hose at the caliper. The typical symptom is that the caliper won't release and the pads wear quickly, sometimes ruining the disc due to overheating. The cause is the failed hose acts like a check valve holding pressure on the caliper after the MC is released. The diagnosis is to apply then release the brake, try to spin the wheel. If it's stuck, open the bleed valve on the caliper. If the wheel spins freely, the hose has collapsed inside and is acting like a check valve.
In your case, this may be why the first new pads dragged.
I don't have your experience of soft pedal but if the hose can fail like a check valve, it sure might act like a "flexible reservoir" and inhibit pressure from the caliper.
I believe your model has 3 flexible lines in the rear; one on each caliper and a third at the pumpkin. They're not cheap (likely $30 each) but that's where I'd start.
Hope this helps

 

I better explain a bit better. The vehicle had no issues other than the squealing of the wear indicators on the rear. At that point it was a simple rear pad change. There was no locking up of the caliper.
I changed the pads and THEN the calipers locked up. This is a fairly common issue as I found with several threads as the calipers are aluminum and they frequently get stuck AFTER a pad change.
So I changed the calipers and there is no more locking. BUT, there is now no rear braking going on. I can bled the brakes properly and clear fluid with no bubbles comes out of both rear calipers.
But the pedal goes half way to the floor. It only engages when it reaches the point of the front brakes.
I can drive the car (30-40) miles so far with no calipers locking up. Its just that there is no rear braking happening.
If you read the thread I posted above, this EXACT issue has happened to another person. EXACT.
In fact there are several threads on the net referring to not being able to get the rear brakes to work after a pad and caliper change. Some report bleeding the ABS lines cures it. Some suggest taking it to the dealer where they can use the scan tool to reset the ABS. One reports bleeding the proportioning valve as it gets stuck, preventing the fluid from going to the rear.
On a side note, neither the NAPA or Autozone parts stores have the correct listing for the rear brake lines. I went there, bought what they had and it is incorrect. Took mine in and they have nothing that resembles it.
I've experienced the collapsed line during my career and you are correct, it would produce a locking caliper. But in my case, that was not exactly the issue.

I did see a Blazer identical to mine at the Pick and Pull with the two rear lines still attached. I am going to nab them today for cheap and try them. Nothing to loose and at least I can eliminate them. I'll post the results.

Thanks, keep the suggestions coming for future users..

Gary

 

Have you checked the hoses to the calipers to make sure they have collapsed internally?