Have brakes pedal sinks low

wnyred · Post by **wnyred** » Wed Aug 31, 2011 2:20 pm

I have a problem w/ my brake pedal going very low. I believed it was a bad master cylinder after a series of brake work being done. Ive replace both back calipers,pad,rotors, though there is one side still has an old bracket*didnt come w/new. So initially I took it to a shop they bled the brakes,and I have brakes but the pedal doesnt feel firm till you're close to the floor. When I suspected the master cylinder got screwed up from being bled so many times/pressed to far,debris around the seal/age whatever. I took it to the chevy dealer. He confirmed by pressing the pedal that was it. So I take it in got a new master,bled A OK you're all set. So now this is the second pro shop that charges 80 bucks an hr,and I still think something else is wrong. Perhaps the modulator needs to be bled? Is that standard for a shop to do when they replace the master? It seems like no one wants to mess with that. Well thats kind of why I took it to a gm dealer. If anyone should know,shouldnt they? Its a 2001 truck.

killian96ss · Post by **killian96ss** » Wed Aug 31, 2011 3:01 pm

I had a similar probkem with my 01 Crew Cab. After trying everything you've already done the dealership ended up replacing the vacuum booster or power booster. It still doesn't make sense to me, but it did fix the problem. The booster uses engine vacuum to help apply the brakes. If the diaphram inside start leaking or the spring breaks or wears out you lose the power assist. Your problem might still be the master cylinder even if it's new, but it could also be a bad booster.

Steve

roadrunner · Post by **roadrunner** » Wed Aug 31, 2011 5:32 pm

I had low/no pedal at one time also and it was traced down to insufficient clearance on the brake booster rod. Shortened it 1/64th of an inch and no more problem. Also have a co-worker that had the same problem on an s10 reg cab 4x4. She had the booster and master cyl replaced 3 times by three different mechanics and was really upset when I told her what it only took to fix that problem on my truck. She ended up selling her truck, which she really liked, for about 25% of what it should have been worth since nobody seemed to be able to fix the problem. All this 2yrs before I met her.

wnyred · Post by **wnyred** » Thu Sep 01, 2011 5:51 pm

@Crew K Elite
I did do a look over previous posts. From what I gathered from them if that was bad wouldnt the pedal be hard? It is so strange.

roadrunner · Post by **roadrunner** » Thu Sep 01, 2011 6:50 pm

wnyred wrote:@Crew K Elite
I did do a look over previous posts. From what I gathered from them if that was bad wouldnt the pedal be hard? It is so strange.

In my case I had low/no pedal at random times. Only common condition was driving on washboard roads. Go for the brakes all the way to the floor and surprise no brakes at all. pump them up and worked fine till another random time then a repeat. Occurrences could be back to back or hours/days apart. That was the truly disturbing part. I can also see where a no-release symptom could occur as well especially if driving on mainly smooth paved roads. Insufficient rod clearance could prevent full release of brakes leading to a brake dragging situation.

killian96ss · Post by **killian96ss** » Thu Sep 01, 2011 7:51 pm

wnyred wrote:@Crew K Elite
I did do a look over previous posts. From what I gathered from them if that was bad wouldnt the pedal be hard? It is so strange.

That's why I said it didn't make sense to me, but it did fix the problem. I was getting very frustrated with the problem and felt my CC was unsafe for my family to be driving in. Sometimes the pedal would go ALL the way to the floor! It didn't do it every time we stopped. It was very random. They replaced the master cylinder and bled the brakes 2 or 3 times with no change. Then one of their techs said it might be the power booster, but it was a fight to get the warranty company to pay for it since there was no guarantee it would fix the problem. After some haggling they approved the repair and luckily it did fix the problem. I mentioned it here because your problem sounds exactly like the one I had. I hope you get it figured out! It's no fun wondering when it will happen again, and hopefully it doesn't happen in an emergency situation!

Steve

wnyred · Post by **wnyred** » Fri Sep 02, 2011 5:33 pm

yeah i can see where if I have to stop fast,it could be an issue. If i just brake easy,they are working but if you really press they keep going. Maybe they are a bit slow to catch as well,idk. I still seem to think that modulator has air in it. So may try to get a shop to bleed it,just to eliminate the thought in my head....

killian96ss · Post by **killian96ss** » Fri Sep 02, 2011 5:47 pm

Go to a GM dealership or somebody who has a computer that can activate the ABS module while bleeding the brakes. That is the only way to completely get all of the air out of ABS unit.

Steve

wnyred · Post by **wnyred** » Tue Sep 13, 2011 2:22 pm

I did steve. Actually I thought i was making a smart move by going there and Ive had nothing but problems. I actually stopped there on the way home today to say that I changed the one rusty bracket in the back. He can only recommend they go over the whole brake system and see. My thought is, its been here twice for brake issues. Should'nt that have been done by now? UGH. Twice to a dealer,once to another place thats 80 bucks an hour....

killian96ss · Post by **killian96ss** » Wed Sep 14, 2011 8:50 am

I have had similar frustrating experiences with GM dealerships! I had more than 1 bad experience at my local dealership, so now I drive pretty far to another dealership to have work done when needed. Sometimes the problem is the management, and other times it's the inexperienced techs. There are only 1 or 2 local independent mechanics I trust, unfortunately they don't have all the equipment that GM dealerships have for our vehicles, so I just have to deal with it sometimes. Are you still having problems?

Steve

wnyred · Post by **wnyred** » Sat Sep 17, 2011 8:13 am

I actually took it back in yesterday. The place said they got some air out of the modulator for the abs. I don't know if they got it all. Pedal is still similar,low. Im gonna move on and look into the brake booster. From what I was reading Im starting to see where maybe that is an issue.

killian96ss · Post by **killian96ss** » Sat Sep 17, 2011 8:57 am

The booster might be the problem, but it also might be something else. I was very surprised it fixed my low pedal problem! Human error can also cause problems! For example if you had a new master cylinder put in, was it properly "bench bled" before it was installed in your truck? It has to be completely purged of air before it's installed. If it's not, no amount of bleeding afterwards will remove all the air and you will have a spongy feel or low pedal. When you bleed brakes you also have to make sure the fluid in the master cylinder never runs too low or dry because it will suck air in and then guess what, you have to remove the master cylinder and bench bleed it again. These are just a few examples of how simple mistakes can prevent the problem from ever being corrected. When you take your truck to a dealership to have the brakes fixed, make sure when you pick it up that the problem is gone, if not turn around, go back and tell them it's still doing the same thing. You paid for the repairs, and they warranty the repairs only for a certain amount of time. Keep us posted on the results, so we can all learn something!

Steve

wnyred · Post by **wnyred** » Sat Sep 17, 2011 9:06 am

If you remove the master from the booster. Its not gonna let air in is it? Im thinking I would like to see if adjusting the rod raises the pedal,or if something in there is wiggy.

wnyred · Post by **wnyred** » Sat Sep 17, 2011 9:08 am

also....the master has been replaced since this issue started,so i would think the dealer bench bled it before hand....(can't really assume anything lol).

roadrunner · Post by **roadrunner** » Sat Sep 17, 2011 12:52 pm

Never assume repairs were done correctly. Mistakes are made usually unintentionally. If you try to adjust the booster rod be VERY CAREFUL it requires some free play or you will introduce new problems which are equally frustrating and dangerous as well.

killian96ss · Post by **killian96ss** » Sat Sep 17, 2011 6:19 pm

Removing the master cylinder from the booster will let air into the lines below it, but it won't let air into the MC itself unless you let all the fluid drain out. In other words if you remove it and keep it full you don't have to bench bleed it again. You will have to bleed the rest of the system again since you will let some air in. There needs to be a little bit of free play in the rod or the brakes will drag or stay on a little which isn't good. I have seen adjustable rods for custom made systems that you can adjust to you liking. I don't personally recommend adjusting the rod unless you have always had problems. If the rod was the problem it would have always been there, or at least that's what I'm thinking. I think you either still have air in the MC or ABS unit, or you need a new booster. Maybe both! Brake problems can be frustrating!

Steve

wnyred · Post by **wnyred** » Sun Sep 18, 2011 9:05 am

Whats frustrating is apparently no one is following the right procedure. Bleed the abs,bleed the brakes,bleed the abs again. It does'nt sound to difficult to understand. Over and over I take it and hope......and just get the same result.

wnyred · Post by **wnyred** » Tue Nov 08, 2011 3:23 pm

Update
Still having problems. It got to a point where it seemed to get worse. Finally while a mech. was driving it,a line near the master cylinder broke. Then he noticed it looked like the hydraulic control unit leaking/seeping?idk. Anyway 1400 bucks later w/ a new hydraulic control unit,and brake line. ITS STILL A WEAK SPONGY PEDAL>I HTE MY CREW CAB

roadrunner · Post by **roadrunner** » Tue Nov 08, 2011 4:43 pm

Just mulling over your ongoing problem here and it occurs to me you may be having brake hose/s problems. Somewhat rare but definitely possible. Step on brake and fluid is allowed to expand hoses that are going bad instead of applying the brakes thus giving a low spongy pedal. You would need a helper to check this. Helper alternately applies and releases brakes with engine running (causes increased fluid pressure in the system) while you inspect the two front and the rear hoses for any noticeable expansion/contraction while cycling the pedal applied/let up. Given all you've been through I know this seems a stretch but it sounds like basics have been covered. Also since you've replaced pads etc it sounds like you're capable of brake repair work so I would suggest you get a set of "Speed Bleeders". This would allow you to self bleed your brakes at the wheels saving you some of that expensive shop time. I have and have used them and if you're alone working on a vehicle they work well. They are available at NAPA and online stores and there is a thread on this forum discussing them as well.

green02crew · Post by **green02crew** » Thu Nov 10, 2011 4:37 am

Very good suggestion roadrunner. That is a common problem with older motorcycles. The rubber lines get weak and expand losing brake performance. Lots of people go to the stainless steel braided lines to fix the issue.

wnyred · Post by **wnyred** » Tue Nov 15, 2011 3:37 pm

I have considered the rubber brake lines. I was thinking my problem started after replacing rear calipers. Then again,the problem really started when A buddy did rear axle seals. In doing that a brake line broke. He replaced it,we bled it. Felt fine but after that is when the rears started seizing up,not one but both at diff times. Im thinking maybe there is a chunk of debris in there floating around or something. I was so anxious to just throw new stuff on because I had just gotten the truck. I probably should have thought this through better! So revisiting that before I spend any more money!

roadrunner · Post by **roadrunner** » Tue Nov 15, 2011 6:45 pm

I'll proffer another idea for your consideration as well. This has happened to me on one of my vehicles and on a customer vehicle once in the past. Care must be taken during caliper service to support the caliper/s while off the brackets for the following reasons. Letting the calipers hang or drop by the hoses can damage the hoses through kinking or twisting which can cause either of two odd problems the first as we have discussed can be weakening of the hose causing the hose to absorb (balloon) the pressure of brake apply fluid resulting in a soft pedal. The other is more rare. The hose can be damaged to the point it will collapse on the inside thus alternately blocking or allowing fluid to pass which results in some rather odd brake behavior that is hard to diagnose. Sometimes the mounting brackets or ends on a hose can be clamped down improperly also causing this problem. The only way I was able to find this on a van I used to own was remove the hoses and try to shove a wire through to determine for certain if they were blocked or not. On some hoses with angled ends this is a real problem and only blowing through them will indicate if they are blocked. Even that is not fool-proof as if the inside of a hose is damaged it may close up under braking pressure and be unaffected by simply blowing through it. Not trying to introduce more problems for you. Just passing along problems/solutions for rare problems I have experienced.

wnyred · Post by **wnyred** » Sat Nov 19, 2011 8:44 am

It is frightening to even mess with this to me anymore. Its frightening to take it somewhere. It sounds like its very easy to mess up some of the abs valves etc. If I cant figure out whats up soon Im prob gonna cut my losses and trade it in. Trade in rip off,I never thought I would consider. Believe me if I can narrow it down,I would gladly put all new replacements for the rubber lines! I just paid 1400 bucks for an hcu installed(a warranty paid half) but thats some serious money when the whole truck was 6k.

Post by **HenryJ** » Sat Nov 19, 2011 8:47 am

If you have paid $1400 to have the problem fixed and the shop did not fix it, I think it should be sitting there until they do fix it. This is especially true if it is a safety hazard.

wnyred · Post by **wnyred** » Sun Nov 20, 2011 7:12 am

HenryJ wrote:If you have paid $1400 to have the problem fixed and the shop did not fix it, I think it should be sitting there until they do fix it. This is especially true if it is a safety hazard.

You would think. That was to replace the hcu. Thats it. The place calls and says you're all set. I go down there,I said to the guy so its all set? If it was your truck you are happy w/ the way the pedal feels,brake works? Oh yeah blah blah. I didnt even leave the place,as soon as I got in and put my foot on the pedal I knew it was bs. I told him so,its my guess that its just a money grab. They are'nt going to troubleshoot something unless its 80 bucks an hr even if you just spent 1400. All the places I go are like that. Ive talked to them and if I cant atleast narrow the problem Someone else is gonna have to. The real kicker is between this and my moms car(that i have to maintain basically) Ive spent about 2500 dollars there in two months.

Post by **HenryJ** » Sun Nov 20, 2011 8:43 am

Building a good relationship with the people you deal with can pay great dividends. It can be hard to do that in today's market. Parts store counter people seem to come and go frequently. Automotive technicians the same. The service managers can be difficult to get close to. They need to move the rigs in and get them out.
I can sort of see where they are coming from. I don't have the additional baggage of seeing your appearance, the condition of the vehicle or the attitude presented. Given a vehicle and a customer that says the pedal feels spongy, I'm probably going to be a little skeptical. The customer doesn't want to spend thousands fixing this.

Does it stop? It sounds like it since you're still driving it. It still feels spongy? Some brakes do. I have some cruddy brakes on a couple Fords in the fleet. They really suck, but they stop.
You have replaced the master cylinder, booster, calipers , fluid and ABS pump. Sure we could replace the rotors, pads , lines, pedal, pushrod, and more but really? There is just nothing left to replace. It has been bled to death. I think that I too would be to the point of giving up too.

You have a couple choices. If you are capable, follow the direction that has been given you in the previous posts. Take the time to troubleshoot everything again yourself. Bleed the brakes, test the booster and check it for proper adjustment, sand and re-bed the pads to the rotors , maybe even replace them with a performance pad/rotor, check each caliper and their slide pins.
Or ask around and be ready to travel a good distance to find a shop that can and will help you. Pay them well and have the job done to your satisfaction. Ask them if it can be fixed, don't demand that they do something. Taking these suggestions to a mechanic will get you an eye roll and is not likely to help build that good relationship. If this is your plan, simply inform them what has been replaced and ask what can be done to improve the condition.

I can say that I'd be more than happy to help you if you're willing to dive in and help yourself. There must be some equally helpful people who you can bribe with a beverage over there.

roadrunner · Post by **roadrunner** » Sun Nov 20, 2011 10:57 am

I have one additional diagnosis suggestion. With the engine off and the truck stationary in park pump the brakes till the booster is exhausted of vacuum. Take your foot off the pedal for a few seconds. Push down on the pedal ONCE. Is it solid feeling? Is it low to the floor (travels a lot)? Take note of these things. Now pump the pedal a couple times. Does the solid height of the pedal increase significantly (like double)? Is it solid after pumping up? After doing all this you can glean the following information from the procedure.
(1) Soft pedal at any time during this procedure (after booster is exhausted) means air trapped somewhere in the system.
(2) Low but solid pedal on initial single stroke means excessive travel of a brake component or an improperly adjusted pedal free-play situation.
(3) Solid pedal on pump up situation means system fluid situation okay but again excessive brake component travel.

After doing this procedure and evaluation then pump up the brake pedal with the engine off. Next while still holding the pedal down with your foot start the engine. The pedal should sink after engine start about 1/3 to 1/2 its prior height. If it does that means the booster is likely functioning properly. If not attention to the booster is needed. Now take note of the pedal feel. If it feels spongy you should look to your brake hoses for damage and loss of integrity as described in a previous post.
PLEASE NOTE: THE FEEL OF THE PEDAL MAY BE A LITTLE SOFT AS COMPARED TO THE ENGINE OFF TESTS AND THIS IS NORMAL!! This is because of the design of the booster system itself and nothing can be done about it. Some of the "give" in the pedal is caused by the booster itself. Does not mean it is not working correctly! This is a judgement area and an EXCESSIVELY SOFT PEDAL DOES MEAN A PROBLEM.
I too have an 01 truck and the pedal static test is high and VERY solid. There is a bit of give in it while running and the booster is active. Hope this helps you. I don't know how to make it any plainer than this.

wnyred · Post by **wnyred** » Sun Nov 20, 2011 3:36 pm

Idk I feel like you are being a bit condescending,Henry j.
Thanks roadrunner. I did all the booster test stuff I found online. I did'nt replace it and have never taken it apart. I did have someone awhile ago apply the brakes while i inspected the hoses. I have not attempted the pinching off the lines till now. So if my prob is in the rear,I just tried pinching the rear(also I only have two v grips). Im afraid to really pinch them,but did maybe a third then halfway. Is that enough to notice a diff?Whats pinching to much? I did remove the calipers check out the pins,pads etc. Tried reseating them. W/ the rear jacked up in drive w tires off it does stop them from moving. Is it normal tho for your rotors to get pushed around,given the wheels are off? because it seemed to alter the way they rotated.
One thing I am sure of there is something wrong,its not in my head. I have owned many vehicles. One I had previously was a 2000 extended cab w/20,000 miles and the brakes on this crew cab felt every bit as good until changing calipers after they started locking up. Im not quite sure what my appearance has to do with someone not knowing what a spongy soft pedal feels like. Not taking the time to take a two minute drive when you are supposed to be confirming somethings repaired. I took it in to troubleshoot it,they found that problem,fixed it and called it good. I come here to ask questions,if someone says uhhh take it to a shop,and i have it is what it is. I don't need to be judged on all these other levels-thanks.

roadrunner · Post by **roadrunner** » Sun Nov 20, 2011 5:31 pm

wnyred wrote: Whats pinching to much? I did remove the calipers check out the pins,pads etc. Tried reseating them. W/ the rear jacked up in drive w tires off it does stop them from moving. Is it normal tho for your rotors to get pushed around,given the wheels are off? because it seemed to alter the way they rotated.
One thing I am sure of there is something wrong,its not in my head. I have owned many vehicles. One I had previously was a 2000 extended cab w/20,000 miles and the brakes on this crew cab felt every bit as good until changing calipers after they started locking up. Im not quite sure what my appearance has to do with someone not knowing what a spongy soft pedal feels like. Not taking the time to take a two minute drive when you are supposed to be confirming somethings repaired. I took it in to troubleshoot it,they found that problem,fixed it and called it good. I come here to ask questions,if someone says uhhh take it to a shop,and i have it is what it is. I don't need to be judged on all these other levels-thanks.

I have personally never been comfortable with "pinching" any brake hoses. Too much possibility of damaging a hose if it's a little older or slightly brittle. Yes the rotors could get pushed around being braked with the wheels off since the wheel studs are the anchoring point for them with the wheels/lug nuts in place and the rotors can float on their mounting pins. Not saying anything is in your head just pointing out sometimes expectations exceed reality. Don't know what you're referencing with the appearance statement? I am not judging you either. I simply broke the diagnostic procedure down to the most basic level I could competently explain here because it seemed the more suggestions proffered the more questions seemed to arise rather than get solved. You will also notice I've not told you to take it to a shop. I firmly believe if someone demonstrates at least a moderate level of mechanical knowledge we here on the forum should try to help them. I do often refrain from mechanical advice to some who by their very questions demonstrate they should not be working on their vehicles. Some just do not have the basic skills and mindset to proceed safely with diy repair work and I try not to be a party to helping them get further in trouble than they manage by themselves. This is not condescending it is just refusing to help make a bad situation worse for the above stated reasons. Hopefully some of what has been posted here is helpful to you. There are more than a few competent to superior automotive technicians on the site. Hopefully the depth and detail of this explanation will indicate to you where I stand in that group. Bear in mind the help you receive is directly related to the skill and detail you depict in your questions since none of us are able to be there physically to assist you and depend on what you describe to formulate a diagnosis and repair suggestions.

F9K9 · Post by **F9K9** » Sun Nov 20, 2011 5:41 pm

wnyred wrote:Idk I feel like you are being a bit condescending,Henry j.............

You're feelings are incorrect on this one. Brule may get a little harsh, at times but, never condescending. I'm the hatchet man when it comes to telling someone when they need to change their attitude. Brule is giving very sound advice and it comes from many years of experience in the automotive field. Everyone here has tried to give you the best advice, from their experiences, and nothing more. I can relate to your situation because, I burnt a couple bridges, locally, before listening to advice given here.

It's all good! You just need to relax, back up and try another approach to solving your situation.

wnyred · Post by **wnyred** » Sun Nov 20, 2011 7:25 pm

So roadrunner how would you ever narrow down a problem to begin with if you don't believe in pinching hoses. At this point,im done randomly replacing things. I would like to eliminate any possibilities.
You go on these forums,a lot of info is contradictory. For instance never pushing caliper pistons back in. One person swears it will damage the abs system. One person thinks the notion is ridiculous. So its a real gray area on what any mechanic practices. Just an example. Like this,most things ive read say to pinch off the hose at all calipers,get a firm pedal and remove them one by one till you find the funky one. Im not really keen on pinching them either,but replacing them for the hell of it is'nt sounding so good either. Maybe after everything else is eliminated.Idk.

roadrunner · Post by **roadrunner** » Mon Nov 21, 2011 7:55 pm

wnyred wrote:So roadrunner how would you ever narrow down a problem to begin with if you don't believe in pinching hoses. At this point,im done randomly replacing things. I would like to eliminate any possibilities.
You go on these forums,a lot of info is contradictory. For instance never pushing caliper pistons back in. One person swears it will damage the abs system. One person thinks the notion is ridiculous. So its a real gray area on what any mechanic practices. Just an example. Like this,most things ive read say to pinch off the hose at all calipers,get a firm pedal and remove them one by one till you find the funky one. Im not really keen on pinching them either,but replacing them for the hell of it is'nt sounding so good either. Maybe after everything else is eliminated.Idk.

Did you follow the procedure I outlined in the previous posts? That goes a long way towards narrowing problems down and I don't like to randomly replace parts either. Never did and did not have much respect for those who did either.

To shed a bit of light on pushing caliper pistons back: The proper procedure is to open the bleeder screw on the caliper you are going to push back then push it back allowing the excess fluid to exhaust through the bleeder and topping off the master cylinder with clean new fluid. Reason being so you do not push old or contaminated fluid back up the system possibly messing up other components such as an abs or similar unit.

I do not make these statements lightly and am a former certified master technician with over 25 years of both dealership and private shop professional experience. I no longer work in a shop and confine my mechanic work to my personal vehicles and a very few close friends or relatives as I have a non mechanic related job elsewhere. Not my intent to blow my own horn. Just wanted you to know when you tap into the knowledge and advice here from myself, HJ (who is also a technician of considerable experience), and several others too numerous to mention we are genuinely trying to help you and not trying to lead you astray.

If you feel you must pinch off the hoses it's up to you to decide that. I personally would not as in my opinion you will end up replacing them in a short time frame later. Just my considered opinion based on past experience.

I really believe until you do the diagnostic procedure I outlined above all the discussion of the problem here will be of no avail. Let us know what your findings are after that procedure and with that additional knowledge and information perhaps we will be able to narrow your problem to a specific area or component.

rlrnr53 · Post by **rlrnr53** » Mon Nov 21, 2011 8:31 pm

Roadrunner, I know what you mean in regards to opening caliper bleed screws. I made the mistake of not opening them on a van i had. That miscue cost over 700.00 to repair, messed up the ABS module.

roadrunner · Post by **roadrunner** » Mon Nov 21, 2011 8:48 pm

Yep, rlrnr those lessons are expensive and hurt but are never forgotten. I have learned many myself over the years. Too many.

wnyred · Post by **wnyred** » Sun Nov 27, 2011 9:48 am

[quote="roadrunner"]Did you follow the procedure I outlined in the previous posts?

I had found all that info about testing out the booster quite some time ago. It seemed ok. To recap.
Never had a problem w/ the brakes.
Broke a line on rear axle,replaced,bled. OK. Rear brakes would randomly lock up after this point. This is where the problem originated,then complicated by-
Replacing the calipers I could not get one to stop leaking. Making bleeding impossible.
Took it to a garage close to home. They got it to stop leaking and Yes it stops,not efficiently,but the feel and pressure of the pedal was never the same. So I was never sure if something got damaged driving it from here to there, I don't know how low the fluid got.
So at this point had a mech. at chevy dealer confirm the thought it was the master cylinder.New master cylinder,bleeding procedures. Pedal felt no better,no change. They did'nt charge me for it.Took it back to them a few times,nothing.
So back to the orig. shop close to my home. This time while troubleshooting it a line broke near the master. And for some reason now they said my hcu was bad. Which if it was,why couldnt they find that before? they have the latest equip. So this makes me nervous. Was it bad,did I ruin it,did they ruin it? At any rate lots of money later,I can't notice any difference at any time.
At any rate I have read quite a bit,narrowed down what I could. w/o the wheels on running and braking,it seems like one or the other wheel do bind up but I dont see why. On one I thought it was the e brake,took the bracket off, its clearing it fine.Soooo......Cleaned up the back rotors,which are'nt old. Bought new pads,put them on. Opened the bleeders to push the pistons back in on the caliper. And to be honest, I don't think its done a damn thing. Im going to see whats what now with the tires back on and it off the ground. Soooooooo Short of having another bad component I am lost. At this point replacing the hoses in the back is probably not a bad idea. I wish they made a set of the braided metal hosing for all three in the rear,seems like it would have to be custom. Or just do the oe rubber.Idk this stuff drives me crazy. Thanks to all for any advice. Its a nice truck otherwise,anyone want to make a purchase?lol

Post by **HenryJ** » Sun Nov 27, 2011 11:27 am

I replaced my brakes with the Hawk Performance pads and a nice set of Powerslot rotors. They never did feel the same. They just didn't work until heated. First stop in the morning was scary. Sometimes I wondered what might happen if that was a critical situation. Offroad they were noisy. Chatter and squeal to the point of embarrassment.
I complained to the pad manufacturer and was told to sand them down and re-bed. That did not help. I do follow a good bedding procedure and it has served me well on hundreds of brake jobs. These may have been good "race" pads, but lousy truck pads.
Over time I became accustomed to them. I can't say they got better, even though they may have. At times that first stop in the morning would still give my heart a jump.
The truck stopped. It could stop well. I made a mistake in choice of pads that will not happen again.

It is impossible to diagnose a problem that is not clear cut. You do have some problems that I have never seen before. Lines that will not stop leaking and lines that break are unusual.
I have never replaced a rubber brake line that did not show signs of degradation or damage. Add braided lines if you wish, but they would be very last on my list for upgrades.

Keep an open mind. Approach this again from the beginning. Do everything again. Don't be so close minded that it has been done once and is not a problem.

Test the booster with a vacuum pump. Check the pushrod freeplay. Too much is as bad as none.
Bleed one quart of new brake fluid starting at the farthest working to the closest. 1/2 pint from each caliper. Yes, that will take a while. Once done the pedal should be up and firm. If it is not check the master pushrod for proper length. Consider the master is faulty.
Sand the pads and rotors if they are in good condition. If they are marginal or show signs of bluing, replace them with a nice set of slotted rotors (Powerslot or Reactive One) and AC Delco OEM, or Adaptive One ceramic pads. Don't buy lifetime brake pads. They live forever, but they don't stop. The lifetime pads usually sacrifice the rotor. Cheap brakes might stop good , but don't last. Cheap rotors may have uneven iron content.
Make sure the pads are installed in the proper position. There is a difference between the inner and outer pads.
Clean and re-lube the slide pins while there. One or the other binding indicates that they are not moving freely.
Bed the brakes right. Never stop completely when bedding them. Warm them up with three light brakes. 5-0 three times lightly. 15-5 three times medium. Then three hard stops from 60-15. You should smell hot brake on these stops. Give them time to cool between. Allow time for them to cool with a nice long highway drive before you quit.
When you are done the rotors should have a light gray haze to them. That shows the proper pad material transfer.

Moral of the story: It can work right. Something may have been overlooked. Anything worth doing is worth doing at least twice. Start fresh and with an open mind. Another $500 into a truck worth ten times that is worthwhile.

roadrunner · Post by **roadrunner** » Sun Nov 27, 2011 11:52 am

wnyred wrote: Broke a line on rear axle,replaced,bled. OK. Rear brakes would randomly lock up after this point. This is where the problem originated,then complicated by-
Replacing the calipers I could not get one to stop leaking. Making bleeding impossible.
Took it to a garage close to home. They got it to stop leaking
At any rate I have read quite a bit,narrowed down what I could. w/o the wheels on running and braking,it seems like one or the other wheel do bind up but I dont see why. At this point replacing the hoses in the back is probably not a bad idea. I wish they made a set of the braided metal hosing for all three in the rear,seems like it would have to be custom. Or just do the oe rubber.

Was the rear line a steel line or one of the hoses?
Where was the new caliper leaking? (piston seal, porosity, bleeder, other)
What was done to repair the leaking caliper?
With the wheels on and rear off the ground do the rear brakes release engine running and off with booster exhausted as well? Some drag is not uncommon but you should be able to turn them by hand by grabbing the wheel with the truck in neutral and turning either direction. Checking for bind with the wheels off is inadvisable as the wheels bolted down tend to help center and stabilize the rotors preventing dragging from rotor/pad misalignment.
I hesitate to tell you at this point to replace the rear hoses as I don't think we've yet properly diagnosed and located your problem. I would not be afraid to use the aftermarket rubber hoses if you do replace them. They are of generally good quality and will perform adequately. Braided hoses are nice and better but not an absolute necessity.
Brake hoses should also be checked by hand along each hose full length by squeezing moderately with your fingers. Replace if ANY soft spots are detected. Also check for damage, dry rot, bulges or other visible damaged areas.
Additional note: 2001 S10 service manual states the maximum pedal travel with engine and ignition off and booster vacuum depleted with 100lbs of force applied to the pedal is 2.5 inches. Personal note during this check the pedal should be VERY solid as well.
I know this sounds like a lot of messing around but given I'm not there it is a procedure you can follow and report results I can draw on to help diagnose/repair your problem. I edited down your previous post so we wouldn't take up so much room.
An additional note: The service manual states it is not uncommon to use up a pint or more of fluid per each wheel during bleeding of the brake system after replacing the abs module or other forward components of the system and emphasizes running the Scan Tool Automated Bleed Procedure after initial bleed procedure. It then says to repeat bleeding at all 4 wheels to purge any remaining air. I have been unable to find reference to what this automated scan procedure consists of other than simply checking for codes stored in the system unless perhaps it is a procedure contained in the scan tool only.

wnyred · Post by **wnyred** » Sat Dec 03, 2011 10:43 am

I appreciate all of your advice. I have come to the conclusion that there are several problems that have made this situation complex. As for bleeding, I have to trust to an extent that the abs system has been bled w. up to date equip.
Going back to the initial problem( which at the time seemed obvious). The brakes were great to begin with. Changing the pads was only b/c they were soaked in axle grease. They still worked good. When that line broke,sitting in the garage,perhaps debris got in there. The friend who was doing the work(who is a mechanic and has been for twenty years) also I am certain pushed the fluid back through the system to put the new pads on. So my thinking that replacing the calipers was off apparently. At that time he pretty much must have had an idea something seriously got whacked b/c he suddenly seemed to want nothing to do with it.Mind you I was paying this guy decent money. Anyway so finally someone notices the seepage on the hcu and apparently that was only one of the problems. I bought new pads and attempted to rebed them. For a few days I did notice a better pedal feel and stop response. Not quite where it was to begin with but better. Than after a few days it kind of seems like its up to something again. So I think some debris is in there somewhere,or maybe theres something wrong with the hoses. The line that broke was the metal line on the passenger side rear axle.The rubber lines do have some signs of age,I believe they are orig. Also I am unsure if there is a seperate isolation valve for the rear in this truck. My thought if there is maybe that also is failing. So where I am at is finding that out,looking for it,inspecting it. Check to see if the new pads are wearing weird,and am considering just replacing the rubber hoses,that would leave one foot of orig metal brake line on the rear axle. When I put the new pads on I opened the bleeder and pushed the fluid out. Then also bled the back to be sure there was'nt air there.I didnt notice anything weird about that. So does anyone know if there is a seperate valve or if its all incorporated into the hcu?

roadrunner · Post by **roadrunner** » Sat Dec 03, 2011 4:13 pm

According to my oem manual the individual valving you speak of is part of the ABS computer which your post says was replaced. It would have to be since the ABS system is capable of applying and releasing individual brakes separate from each other. As far as I can tell there is no other valving in the system such as the proportioning valve used in older vehicles without ABS.
As for the hoses while I do not advocate mass parts replacement as a cure it would seem to be a not prohibitively expensive procedure to do next. Particularly if they are showing signs of age or deterioration. Just make sure to bleed bleed bleed bleed starting at the wheel furthermost from the master cylinder and working your way closer at each wheel. It will take a lot of fluid but at this point that is the least of your expenses to deal with.

wnyred · Post by **wnyred** » Sun Dec 04, 2011 2:57 pm

HenryJ wrote:
Keep an open mind. Approach this again from the beginning. Do everything again. Don't be so close minded that it has been done once and is not a problem.

Sand the pads and rotors if they are in good condition. If they are marginal or show signs of bluing, replace them with a nice set of slotted rotors (Powerslot or Reactive One) and AC Delco OEM, or Adaptive One ceramic pads. Don't buy lifetime brake pads. They live forever, but they don't stop. The lifetime pads usually sacrifice the rotor. Cheap brakes might stop good , but don't last. Cheap rotors may have uneven iron content.
Make sure the pads are installed in the proper position. There is a difference between the inner and outer pads.

Moral of the story: It can work right. Something may have been overlooked. Anything worth doing is worth doing at least twice. Start fresh and with an open mind. Another $500 into a truck worth ten times that is worthwhile.

Ok in revisiting the rotor/pad issue I guess my rotors do have a bluish tinge,so I should replace them?
Also initially I thought,well yeah the pads are on right. I don't know that from personal exp. just the theory of reassembling something the way it was taken apart. So can I tell by the tabs if they are in the right place? Are tabs the same on diff brands?

I guess I have had good luck all ive ever bought for my trucks was basic crap for rotors,and usually the better of the lifetime pads,same for calipers and stuff. Never had a problem.But like anything else,it probably gets cheaper and crappier for more money every year!

Post by **HenryJ** » Sun Dec 04, 2011 3:59 pm

If they have a bluish color they are seeing excessive heat. They should be a dull gray to perform the best.
The blued rotors will be surface hardened. This will make the surface difficult to adhere to as well as having problems dissipating heat. The surface will expand and contract at a different rate and stress cracking of the surface will become apparent. All this will lead to inadequate braking. Increased effort and brake fade will result.
If they are in very good shape, you can try sanding them or "turning them" and re-bedding. Measure the thickness and compare it to the minimum allowed. If you are within .020" it is not likely they will be adequate after turning.
I have had a VERY hard time finding decent rotors lately. The rotors and brake pads sold with the truck are very good. At 60k miles they are about done though and replacements are in order. OEM quality is just not out there anymore. Poor iron content and uneven distribution have led to warping and hot spotting. Even OEM AC Delco rotors have been a problem. PowerSlot and the ReactiveOne are on the top of my list right now. PowerSlot rotors seem to be the only choice for the s-series. Get ready to spend about $100 each for rotors.

High performance pads may have different inner and outer pad formulas. These pads are marked , usually a color and or printed mark. It would be very difficult to see the marks once put into service.
I have had good luck with Adaptive One ceramic pads (F $67.29, R $65.29) I have run dozens of sets in the fleet. They offer good life. Good braking and little dust.
My bad luck has been with "lifetime pads" they wear out rotors and offer poor braking characteristics. The other problem that I had was with the Hawk Performance ceramic pads. They work once heated. Good for a race car, not a 4x4 and daily driver.
I have tried many different pads. I still test them as I find them. AC Delco used to be good. They are "ok", but only if I can not get AdaptiveOne.

Finding quality brakes has been a real struggle lately. I really have not found a suitable inexpensive solution. The best option has been to spend the $$ to get the good stuff.

wnyred · Post by **wnyred** » Sun Dec 04, 2011 4:24 pm

ok. The rotors were new six months ago,so i guess i could get them turned,depending if its worth the cost vs new ones. I know they saw excessive heat when the calipers were sticking(the beginning of the whole issue). I have sanded them though,tried to.

"Make sure the pads are installed in the proper position. There is a difference between the inner and outer pads."

- So how do i know if i have the right pad on for inner/outer?

Post by **HenryJ** » Sun Dec 04, 2011 4:28 pm

wnyred wrote:- So how do i know if i have the right pad on for inner/outer?

Manufacturers directions.
If you are having braking deficiencies, you might consider replacing them with a different pad. I would toss them if the performance is substandard. I came real close to replacing the Hawk pads. I ended up selling the truck instead

wnyred · Post by **wnyred** » Sun Dec 04, 2011 4:35 pm

yikes,they never come with any.thats why i just do it the way they were......

Anyone out there can tell me where the clip on the end of the pad sits inner and outer on the rear pads? Excuse my glaring ignorance!

At this point Id rather know for sure than assume its right.

Post by **HenryJ** » Sun Dec 04, 2011 4:43 pm

Register at Autozone and use their repair guides.

wnyred · Post by **wnyred** » Sun Dec 04, 2011 4:48 pm

I was just looking for the above info I asked about. I came across an instruction to replace pads. It is'nt telling me what im looking for but is specific to this vehicle. It says something about a retaining spring for the inboard pad. As far as I know there is no retaining spring. its just the the top and end pieces and new boots for hardware right? For the rear.

Ok you answered both my questions. Thats funny because thats just where i was,where i read about the retaining spring.hmmm
thank you!

wnyred · Post by **wnyred** » Sun Dec 04, 2011 5:58 pm

I don't know the only visual diff I see is which end the wear indicator is on.

wnyred · Post by **wnyred** » Fri Dec 23, 2011 12:49 pm

So doing the standard 2 person bleed method rr.lr.rf.lf. Can someone tell me should i pump up the brakes w/ the vehicle off,then bleed w/ the ignition on? Idk if it matters on this.
I replaced a rear bleeder,when changing pads,rotors. I figured I would bleed all four wheels(not sure i have to). At any rate in this ongoing saga,my front rotors do look pretty worn as well(they passed inspection,where several things failed so I figured it was good). So maybe that is playing into the whole bad feel of the brakes. They felt good initially so I have been trying to get them back to good.

Post by **HenryJ** » Fri Dec 23, 2011 1:04 pm

Shouldn't matter. You don't need the assistance of the vacuum booster to cycle the master cylinder.
I don't "pump" the pedal. One smooth push and good firm pressure. Close the bleeder quickly when the pedal loses pressure.
Be patient and move the volume. The first will take the longest time. After that the line to the tee has clean fluid and it will go faster.

wnyred · Post by **wnyred** » Fri Dec 23, 2011 1:07 pm

ok thanks Henry.just trying to eliminate probs due to my ignorance.
I bought ac delco rotors.Green stuff pads for the rear.

Post by **HenryJ** » Fri Dec 23, 2011 1:12 pm

I have been having real problems finding decent rotors. The AC Delco Advantage rotors are supposed to be the same as their premium line, only less warranty. I'm still having problems with the rotors hot spotting, warping, and or uneven pad transfer.

Pay close attention to the bedding after you get things together. That will make or break the job.

wnyred · Post by **wnyred** » Wed Jan 04, 2012 6:23 pm

Well so far, it seems to be stopping better,and a somewhat firmer peddle(closer to what originally was by far). So from what ive gathered,the ehcu got messed up,and all the new parts on the rear were overheated in the break in period. The failure was'nt something a shop easily diagnosed(ehcu). As you may have guessed from my posts,I've been a little frustrated*LOTS_! Finally though I've gotten it back together.
I had a hard time fighting the urge to replace the front rotors. I never really considered they would be a problem cause they passed inspection. In my opinion they look pretty crappy. I did'nt want to add in another 150 bucks or whatever to find out there was still a bigger problem elsewhere. Gonna let that ride for now,and work on a few other fav failure issues Im becoming familiar with that are common in these trucks.
Thanks for all your help!