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Good Evening,

My vehicle is a 2000 Chevy Silverado 1500, extended cab shortbed with a 4.8 litre engine.

Just read my post and realized how long it is. I know many don't have time to read all my headaches, but I'll leave it here just for information. My issue is that I have replaced every piece of my brake system but no matter what is tried we can get no pedal pressure - the brakes work fine, just not something I want my son to learn to drive with.

1) New master cylinder (Not refurb) 2) New stainless steel lines, from the master to ABS to all four corners 3) New ABS Control module and New ABS pump (Not refurb) 4) New pads, new Rotors and new Calipers at all four corners

There are no leaks to be found any longer, I have been over the system as well as the current mechanic. His only suggestion at this point is that I have a bad master cylinder. This is the third master to be put on the truck during this trying time, so I am having a hard time swallowing this diagnosis, but if that is it, then so be it. Does anyone have any ideas as to what could be the issue? Any and all help would be most appreciated.

Thanks in advance for any and all help, MJ

A couple years back, 2013, I had to make a sudden stop when a state trooper did a u-turn right in front of me. When I hit the brakes, the pedal went to the floor. As it turned out, I had blown out one of the steel hard lines. I took it to a mechanic and asked them to replace the blown line and to replace any others that appeared to be ready to go, too. In the end, the mechanic only changed the blown line but since I needed the vehicle I had to take it. Everything was fine for a few months, then another line went. I took it to another garage and asked them to replace ALL the hard lines. After having my truck for about a week, it turned out they also did not replace all the lines as requested, but only changed the one front line that blew out. Again, I took the vehicle and went on my way kinda perturbed. Since that time I have hired three more mechanics to change out all the hard lines, even going as far as purchasing a whole kit of stainless steel lines, pre-bent. The first mechanic totally hosed the whole thing, had my truck for months (seriously!) and all he did was run new lines to the front of the truck. Problem was, instead of using the proper lines (everything in the kit was pre=bent and marked), he cut up the long lines that should have run to the back of the truck to do the fronts. After this fiasco, I found another shop going so far as to speak to the owner, explain all the issues I have had in trying to get this job done and he assured me that he could do the job, he was a GM mechanic for 25 years before starting his own shop. I bought another set of stainless steel lines and dropped everything off to him. He told me that the job would cost $500 and be completed in two days.

Two weeks later, the lines were on the truck but he could not get any pedal pressure. He also indicated that he could not seem to get much fluid flowing to the back lines even though he had spent days trying to bleed the system. He determined that the master cylinder was bad - it was brand new. I contacted the manufacturer and they shipped me a new, not refurbished, master cylinder for my truck. It was put on but it did not solve the problem. Then I was told that it must be the ABS system. I purchased a new, not reman, ABS pump and he installed it. Surprise, same issue. I had gotten so irritated at this point that I paid him the $1300 for the work he did and took my truck. I found after getting home that there was a leak at the front line coming out of the master cylinder. I took it back to this guys shop and he kept the truck for another two days. In the end he said that the lines must be bad, he can't make the leak stop.

The truck sat for just about a year, but since my son is ready to start driving I needed to get the truck right since he cant drive my car, manual transmission and too powerful. I hired yet another mechanic, one from my place of employment. He fixed the leak at the master but found that he too was unable to get any pedal. In addition to fixing the leak, he put on new pads and rotors on all four corners. He checked the vacuum booster but it was not the issue. He suggested the master but I told him that the one currently on the truck would be the third new, not rebuilt, in the past year and a half. As it turned out, the only other thing that had not been replaced was the ABS controller. I hated to even entertain making that purchase, but in the end I did and the mechanic installed it, to no avail. He agrees that this should not be so hard to solve, has looked at the whole system for leaks, none. The only other thing he can suggest is that I have a defective master. I want so bad to just buy it and have all this behind me, but dang, how many times do I need to buy one and why after replacing everything in the braking system (except the brake booster) is this still not working.

I've been sitting here for a few days now, scouring the internet looking for answers. Found similar issues, but in the end these folks find their gremlin and all is right in their world. Does anyone have any other thoughts on what could be wrong? Any help would be more appreciated than you could ever know.

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    Welcome to the site and sorry for all your woes! This sounds frustrating. How were the brakes bled? Was the master cylinder bench bled? Was the ABS controller bled separately (as itself)? When you say you cannot get any pedal, does it just fall to the floor or is there any resistance? If you press the pedal and put it in drive, will it keep it from going anywhere (or at least provide some rolling resistance)? Does the e-brake work? This has a vacuum assist (not a Hydroboost)? (PS: I have a 2006 Silvy and used to own a '00 as well.) – Pᴀᴜʟsᴛᴇʀ2 Jul 4 '17 at 23:36
  • Hi Paulster, Thanks for the welcome and the reply. The brakes were bled using a pressure bleeding system, can't recall the brand but it's like the ones Motive make. Yes, The master cylinder was bench bled. Not sure about the ABS pump, though the supposed mechanic claimed to be a GM man. When I step on the brake, the pedal just sinks to the floor, very little if any pressure. The brakes do work and I drive the truck now because I trust myself, but won't let me son drive it. Yes, the e-brake works. Yes, vacuum assist. I can get a little pressure if I pump the brakes while stopping. – Matthew Jul 5 '17 at 0:02
  • I'd look at a couple of things: 1) as @tlhingan stated, check to ensure the lines are hooked up properly; 2) were the soft lines changed? If not, have someone pump up brakes, then inspect every one of them to see if one is bloated (has a swell in it); 3) bleed the brakes again and again until you get some type of pressure ... there's most likely air in there somewhere. EDIT Even if new soft lines, double check them anyway. – Pᴀᴜʟsᴛᴇʀ2 Jul 5 '17 at 0:05
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    Sounds like you need to do an automated bleed of the bypass modulator valve with the appropriate scantool and that's all it's probably all it needed other than the lines. – Ben Jul 5 '17 at 1:31
  • Hi Ben, thanks for your suggestion. Unfortunately for me, the mechanic has already been down that road. After some further reading, I found an article where someone had a very similar issue. One of the suggestions for him was to replace the check valve in the vacuum booster. I received the part today and unfortunately it did not correct the situation. Perhaps I'm crazy but it seems like I got a wee bit of pressure on the pedal but not near enough. The search continues... – Matthew Jul 6 '17 at 21:30
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Lingering issues that aren't getting tracked down are draining for sure. As the owner of some old cars myself, I feel for you. There's a few things you can try:

  • are your new lines bad?: this seems to be when the trouble started. Usually, lines go bad by bursting, as has happened to you at the beginning of this ordeal. But if the new lines are a different inner diameter than the old ones, they will be moving more brake fluid, and your master cylinder may run too low and aspirate some air into the system. This is easy to check, press the pedal all the way to the floor and have your mechanic look at the fluid level. If it drops too low, that's your issue. Get new brake lines and make sure the inner diameter is correct. I've personally replaced the hard lines on my daily driver and rather than buying pre-bent steel lines, I have some made locally with some copper allow that is soft enough to bend by hand. Works like a charm.
  • are your new lines hooked up incorrectly?: Ages ago, my rear bakes wore out. Since the front brakes do most of the work, I wasn't in too much of a hurry to replace them. That is, until I had to do an emergency stop and found I had very little braking power on the car. It turns out master cylinders have proportioning valves that apply brake pressure to the rear and will hold off on applying pressure to the front until the rear have engaged. Of course, the only way a master cylinder knows which lines are the front and which lines are the rear is by WHERE THEY ARE CONNECTED on the master cylinder. Go to the junkyard, find a truck of same make and model as yours, look at the master cylinder and follow the steel lines until you are reasonably sure which one goes to which wheel. Then, pop your hood and make sure yours is the same. It's a long shot, but worth checking.
  • is there air?: the thing about new master cylinders and new brake lines is that they're full of air. You need to fill them up with fluid, connect them and then bleed whatever air is left in them out. Many mechanics neglect to bleed the master cylinder, and I wouldn't be surprised if that's your issue. Bleeding the brakes is easy (press and hold the pedal while somebody opens and closes the bleeder valve), but bleeding the master cylinder is best done outside the car. It's called "bench bleeding" for a reason. It's easy enough to do by your mechanic friend.
  • tlhIngan, thanks for your reply. The brake lines appear to be the same inner and outer diameter. Can't find my caliper at the moment but they look good to me. I purchased the first set from fine lines and the second replacement set was from Dorman. The original lines blew out due to age and rust, GM apparently did not use stainless. I just took a run out to look, and the brakes appear to be connected the way there were before everything was replaced. I will ask the mechanic to take another look. As for the master, I actually bench bled the first master, I'll ask to have it done by a pro – Matthew Jul 5 '17 at 0:21
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Maybe by chance, are the calipers installed upside down? Meaning with the bleeder to the bottom instead of to the top? I put a lift, body parts, etc. on a jeep over the coarse of last winter and decided new calipers would be a good thing as well. On the way back together I just garbed the calipers lined up the mounting holes & bolted in place (brain fart!!! didn't think about the bleeder position at that time). After all painted and assembled, bled the brakes couldn't get a hard peddle but jeep would stop with low peddle. Bled the brakes again still low peddle. The aha moment, swapped the calipers so bleeders were to the top (I was surprised you could actually put them on upside down) and wala hard peddle. Just something to check! Hope for your sake that's it. Godspeed,

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You need to bleed the ABS unit using a special scan tool. Had the same problem with my truck.

  • This point is often missed, resulting in visits to the shop after otherwise competent DIYers have replaced brake components. – mongo May 17 '18 at 20:12
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Just had the same issues. had pressure in the front brakes but nothing for the rear brakes. been working on it for two days and nobody knows what the problem is. bypassed all the stuff that you’ve already done, i went to O’reilys and bought a super seiphener for $5. i attached it to the passenger rear caliper where you bleed the system. cracked it open and attached super siephener to where it’s drawing the fluid out. i did this for approximately 15-20 minutes per side. Then I pumped the brakes lightly and do a regular bleed job. and you should notice a difference in the brake almost instantly. so if you would, let me know if this worked or not, i hope it does. thanks

               ~Brett C.
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Had the same problem. Turn your key to the On position and disconnect one of the brake lines at the master cylinder and pump the brakes a couple of times. Then do the same thing to the other line going into the master cylinder and reconnect it. Now you should have a half decide pedal. I went crazy trying to figure my 01 yukon out and my dad called his friend who is a mechanic and he said to do that. It worked, got pedal instantly and then went around and bleed the brakes again. It was a couple years ago we done it and i believe it has something to do with the ABS that's why you gotta turn the ignition on.

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