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Discussion Starter #1
I looked around on other pages and forums, but could not find the solution to the problem so I am posting it here. After I finished putting the pads and rotors on, the brake pedal was very spongy and there was no brake pressure to stop the vehicle after it started moving, even after compressing the pedal 20+ times before driving. I checked the master cylinder but it was fine. I've never bled brakes before, could there just be air in the system and that is what's causing it? I cracked one of the bleeder valves to hopefully relive some pressure so I could compress the pistons but did not leave it open for very long, and I replaced the fluid that it did use. Any help is appreciated and thanks.
 

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イリジウム
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After working on brakes always pump the pedal to take up pad/shoe travel first with the engine off. If you don’t get a firm pedal the reinspect.

Did the pads move freely in the bracket? You shouldn’t need to open the system up unless flushing with new fluid as I do before changes. So not sure how that much air would get into it if just pushing the piston back. Of course the brake hoses aren’t damaged are they? Any external leaks?

Are the pads contacting the rotors? Maybe pump some more with the engine off and inspect.
 

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. . . putting the pads and rotors on, the brake pedal was very spongy and there was no brake pressure to stop the vehicle . . . even after compressing the pedal 20+ times before driving . . . could there just be air in the system and that is what's causing it? I cracked one of the bleeder valves to hopefully relive some pressure so I could compress the pistons . . .
When installing new pads, you normally have to pump the brakes a number of times to push the pads into place. Twenty times does sound excessive, and the pedal shouldn't be spongy. Cracking the bleeder valve could have let a little air in, but unless the brake pedal was on the return stroke at the time, I wouldn't expect such a drastic reaction.

It's time for you to bleed the brakes.

If that doesn't fix the problem, you might have lost hydraulic seal at the caliper pistons. I've had that problem before when the caliper pistons were rusty. If that's it, you'll find brake fluid leaking. Also inspect for fluid leaking around the brake lines.
 

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Discussion Starter #4 (Edited)
When installing new pads, you normally have to pump the brakes a number of times to push the pads into place. Twenty times does sound excessive, and the pedal shouldn't be spongy. Cracking the bleeder valve could have let a little air in, but unless the brake pedal was on the return stroke at the time, I wouldn't expect such a drastic reaction.

It's time for you to bleed the brakes.

If that doesn't fix the problem, you might have lost hydraulic seal at the caliper pistons. I've had that problem before when the caliper pistons were rusty. If that's it, you'll find brake fluid leaking. Also inspect for fluid leaking around the brake lines.
Since I had already have a new brake booster and master cylinder in boxes, I am just going to install those now, so I don’t have to bleed the brakes twice. In the process of doing that, I snapped and kinked 2 of the brake lines that go into the master, I am not sure what the extra add on piece is that connects the master to it though. Is there anything to keep in mind about bleeding the brakes with the new master and booster? The booster and master worked fine before I changed the pads and rotors, but since I have the parts I will just install them now to avoid any further hassle. The picture below show the unknown part that connects to the master with 2 metal lines.
 

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Discussion Starter #5
After working on brakes always pump the pedal to take up pad/shoe travel first with the engine off. If you don’t get a firm pedal the reinspect.

Did the pads move freely in the bracket? You shouldn’t need to open the system up unless flushing with new fluid as I do before changes. So not sure how that much air would get into it if just pushing the piston back. Of course the brake hoses aren’t damaged are they? Any external leaks?

Are the pads contacting the rotors? Maybe pump some more with the engine off and inspect.
I’m not sure if they moved, but it doesn’t appear that they even engaged with the new rotor because there wasn’t any marks on the rotors from the rubbing of the pads. The calipers worked fine before the pad and rotor replacement. I used a adjustable wrench to compress the pistons because there was not caliper tool that would work for my specific calipers. The wrench did not damage the pistons though and there is no brake fluid around the lines or the caliper itself. So I don’t think I could have damaged it. I plan on doing a system flush as well once I install the new master and booster just so I don’t contaminate the new parts.
 

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Maybe it’s just a coincidence but just changing the pads and rotors shouldn’t do that to you. But since you’re already in there might as well wrap it up. Looks like just the short lines got damaged? Price out dealer parts or bend and flare your own. Get help from mechanically inclined friends if you’re not familiar.

Yeah looking at the rusty parts i’d think it’s probably time.

That part the short pipes connect to looks like the proportioning valve? Not sure if it’s load sensing.
 

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Discussion Starter #7
Maybe it’s just a coincidence but just changing the pads and rotors shouldn’t do that to you. But since you’re already in there might as well wrap it up. Looks like just the short lines got damaged? Price out dealer parts or bend and flare your own. Get help from mechanically inclined friends if you’re not familiar.

Yeah looking at the rusty parts i’d think it’s probably time.

That part the short pipes connect to looks like the proportioning valve? Not sure if it’s load sensing.
Thanks for all the help. And yes it was only 2 of the short lines that were damaged. I originally bought some steel lines but they were too difficult to bend with the correct tool and they were the wrong length. I bought some nickel copper lines that were very pleasant to work with. They bent easily by hand and did not kink at all. I installed the new master and booster, bled the front two brakes, and everything is now working as it should. I plan on replacing the entire rear drum assemblies soon so I will bleed the rear when needed.
 

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Nice job. I suspect when you opened the bleeder valve you let air in and that's what caused the problem. You don't need to do that when just replacing pads. Anyway, glad you got it fixed.

I guess that's a remanufactured MC? Is there a brand name? Where'd you get it? How much was it?
 

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Nice job. I suspect when you opened the bleeder valve you let air in and that's what caused the problem. You don't need to do that when just replacing pads. Anyway, glad you got it fixed.

I guess that's a remanufactured MC? Is there a brand name? Where'd you get it? How much was it?
Thanks! When I bought the truck a few months ago, it came with a bunch of replacement parts and that was one of them. I believe it was from a company called: A1Cardone. I looked it up, and they seem to run about $50 for the complete master cylinder assembly.
 
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