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Weird brake issue on '91 DB1 w/ ABS.

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Weird brake issue on '91 DB1 w/ ABS.

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    Weird brake issue on '91 DB1 w/ ABS.

    About 3-4 months ago my brake pedal started getting mushy and would go to the floor, so like I did on the last few integras I've owned...I replaced the master cylinder. The problem went away, but I noticed that I had to press the brake pedal a little farther than normal before the brakes engaged. I didn't see it as a problem, the brakes worked great and felt good so I drove it.

    Two days ago my dash brake light comes on. I thought the brake light was for just the parking brake, and since my interior is gutted I figured I bumped or spilt something on the parking brake switch so I ignored the light. Completely forgot that light is connected to the master cylinder brake fluid reservoir.

    Earlier this afternoon I got in my car to run to town, and instantly noticed the pedal sink to the floor...the brakes worked but barely, the pedal literally had to be to the floor for the car to not roll down my driveway. I checked all the lines I could see, no leaks. I checked the calipers, no leaks. I checked the reservoir...empty. I filled it(and remembered that this is what the brake light as trying to tell me 2 days ago), bled all the calipers one at a time starting at the rear/left, then rear/right, then front/right and then front/left. The rears put out no bubbles, but put out a very dark brown fluid with debris which has me concerned a little. The fronts put out a small mount of bubbles, and a lighter brown fluid with little or no debris. I bled each caliper until no bubbles were present at all, making sure the reservoir stayed full, making sure my fiance pumped the pedal 10 extra times per caliper after the last bubble to guarantee most/all the air was out of each line.

    After this I decide to test drive the car. Pedal still sinks to floor when car is on, but holds sufficient pressure when car is off. The brakes do work, but not until the pedal is literally to the floor. I'm afraid to drive the car at this point, it feels severely unsafe.

    I don't know if my new(remanufactured) master cylinder went bad in only 3-4 months, if there's some sort of super-disguised leak that is damn near impossible to find, or if my booster is bad. To me it seems like the master cylinder again, but the fact that the reservoir was completely empty has me concerned. This is our only car and we both work...so we're screwed if I can't get it fixed.

    Any opinions/suggestions/ideas?
    Last edited by DOHCIntegraLS; 13 Jun 2009, 02:47:33.

    #2
    Originally posted by DOHCIntegraLS View Post
    About 3-4 months ago my brake pedal started getting mushy and would go to the floor, so like I did on the last few integras...I replaced the master cylinder. Problem solved, except the pedal had a little more travel than normal before the brakes kicked in. Didn't think anything of it, didn't go to the floor anymore and the brakes worked.

    Two days ago my dash brake light comes on. Well, I never let fluids get low in my car so I had completely forgotten that the brake light goes to the parking brake AND the brake fluid reservoir...so I ignored it thinking my parking brake switch had gone bad due to being exposed, I have a gutted interior and figured maybe I spilt soda on it or something. Brakes are still working fine.

    Earlier this afternoon I got in my car to run to town, and instantly noticed the pedal sink to the floor...the brakes worked but barely, the pedal literally had to be to the floor for the car to not roll down my driveway. I checked all the lines I could, no leaks. I checked the calipers, no leaks. I checked the reservoir...empty. I filled it, bled all the calipers one at a time starting at the rear/left, then rear/right, then front/right and then front/left. The rears put out no bubbles, but put out a very dark brown fluid with debris. The fronts put out a small mount of bubbles, and a lighter brown fluid with little or no debris.

    After that was all done, calipers all bled, reservoir full, abs reservoir still full this entire time...I decide to take the chance and test drive the car. The brakes are not working again, but the pedal has to get even closer to the floor for the brakes to engage than it did after the master cylinder install a few months back.

    So tell me...where did all the fluid go in the first place if no leaks are present, and why is my brake pedal needing to be pushed so far for the brakes to engage? If it matters, my ABS light has been on the entire 1 or 1 and a 1/2 years I've owned the car and to this very day I don't know why since the ABS always seems to work. At this time I don't even feel safe driving the car due to the pedal having to almost bottom out before the brakes work...every few times I hit the brakes they'll engage normally about half-way down, about where they should be.
    well ur master cylinder could be bad. if anything....... u might wanna check inside of ur brake booster. i've seen an issue which was extremely rare that the rear seal on the MC leaked, but it was fused to the brake booster due to gunk n residue n stuff, so it all leaked INTO the brake booster. was really really weird. but possible. if i were u tho, inspect that master cylinder or take it back if u can and get another. replace the booster too at the same time. also check all ur brake lines and if they are still the original ones, go ahead n replace them.

    Comment


      #3
      I suppose the master cylinder could have gone bad...but what would explain the reservoir being empty? I replaced the master cylinder with a reman'd unit from Autozone only 3-4 months ago...I bench-bled the new unit and installed it, I bled the brakes, kept the reservoir full during the bleeding and topped it off when the installation/bleeding was done., used brand new Prestone Synthetic DOT3 brake fluid, and used the "open bleed screw/pump pedal until no more bubbles/close bleed screw" method when bleeding those calipers, had the bleed hose submerged in a container of fresh fluid that I watched like a hawk for bubbles while my fiance worked the brakes. I had her pump the brakes about 10 times after the last air bubble on each caliper, just to be 100% sure I got all the air out. I used a brand new section of oem-style vacuum line as my bleed hose...you think that may have been the problem, maybe it wasn't air-tight even though it went on the bleed screw tight enough to almost not fit? I don't have any other hose, and the hoses in the Mityvac kits at autozone look like they're a little too big so I didn't want to waste the 30 bucks on something I couldn't use.

      An empty reservoir 3months after a master cylinder replacement points to there being a leak, but I put new fluid in and pumped the brakes until my leg felt like it was going to fall off while the car was on...the only fluid under the car was a little water condensation drip from my a/c and some oil from my leaky oil pan gasket, no brake fluid anywhere on the ground. All four calipers were and still are bone dry, the insides of my wheels are dry, the rotors are dry...no signs around those areas of any fluid. The front and rear brake lines that run to the master cylinder are dry. The lines running to and from the ABS unit are dry. The ABS reservoir is full, haven't topped it off since I bought the car a year ago.

      At this time the pedal still sinks to floor whether the car is warmed up or cold, and when the car is off the pedal quickly builds pressure and seems to hold it when pumped. This tells me the booster is good and the master cylinder is bad, since the pedal only holds when car is off and sinks when car is on...is that correct? Either way, this still wouldn't explain the reservoir being empty after 3 months. All I know is I need to fix this ASAP as this is our only car and my fiance needs it for work this weekend.

      Even if the master cylinder is bad, what explains my empty reservoir?
      Last edited by DOHCIntegraLS; 13 Jun 2009, 02:40:06.

      Comment


        #4
        Originally posted by Squeezethis View Post
        well ur master cylinder could be bad. if anything....... u might wanna check inside of ur brake booster. i've seen an issue which was extremely rare that the rear seal on the MC leaked, but it was fused to the brake booster due to gunk n residue n stuff, so it all leaked INTO the brake booster. was really really weird. but possible. if i were u tho, inspect that master cylinder or take it back if u can and get another. replace the booster too at the same time. also check all ur brake lines and if they are still the original ones, go ahead n replace them.
        You pretty much summed up a good starting point for this issue, I don't have much to add at all.

        I would IN NO WAY trust the reman master cylinder you purchased. Put that at the top of your list of possible causes for this problem. I can't even begin to tell you how many times I've had a carpart go bad only to replace it with a new (not oem) part which was bad out of the box or failed very soon after. This is the most frustrating thing in the world because you usually cross that item off of your list of possible culprits.

        Here is where I would start:

        1) Put the car on jackstands, make sure ALL brake components are extremely clean. STAND on the brakes with the engine off. Really build that pressure. Do this for awhile. Then immediately check ALL lines, fittings, connections... for any sign of leakage. If there is leakage, investigate it further.

        2) If there is no leak, drain the MC and remove it. Search for fluid leaking into the booster like Jeff mentioned. This isn't that uncommon. And that could explain you not seeing the fluid anywhere.

        Also, when you mentioned your brake bleeding method, I'm a bit confused as to exactly how you're doing it. Are you using example A or example B:

        Example A:
        1) Loosen bleed bolt
        2) Pump pedal to floor
        3) Tighten bleed screw
        4) Release pedal
        Repeat

        Example B:
        1) Loosen bleed bolt
        2) Pump pedal repeatedly
        3) Tighten bleed screw


        I also just realized that you have ABS. Unfortunately I'm not sure how that may or may not be effecting your situation. It shouldn't be, but there's always some off chance. ABS FTL.

        Comment


          #5
          not to rag on autozone, cuz i shop there too. but the name/word AUTOZONE being in ur reply (thread) IMMEDIATELY throws up a red flag. i repeat........ do not, DO NOT DO NOT DO NOT buy any parts from there that have purpose. unless its like a gasket or an o-ring, the only thing i'd get with the autozone/duralast name on it is...... a battery (if even that).

          but yea ur method of bleeding the brakes also confuses me. and not to beat ur balls colin, but even ur 2 suggestion methods confuse me too.

          *this is gonna be uber detailed but hey i got free time*
          HOW I LEARNED HOW TO DO IT: (if i learned wrong then my bad)
          1. remove cap from reservoir.
          2. top brake fluid
          3. lay cap on reservoir but do not have it tightened down
          4. *this is where the actual procedure happens =P* pump pedal down 6 times
          5. loosen bleeder screw (LR>RR>LF>RF). only break it open and let some fluid/bubbles come out. (make sure that pedal pumper DOES NOT LET THE PEDAL REACH THE FLOOR!!!!!!!!!!!!!!!!!!!!!!!!!!!!)
          ***********************
          reason: i learned from instructors and rebuilding master cylinders that when the pedal is pushed to the VERY VERY bottom of its travel (floor) the cups can be pushed so far that they collapse..... this makes them not seal properly. if u've seen the inside of the master cylinder.... its important that these cups only cup in one direction, not in the other and not in both. when they start leaking around the cups, then the seals are more prone to brake fluid and pressure..... this weakens them...... which then causes them to leak prematurely (before they should ever go out). this is the reason i do not do/use/perform the old brake bleed method and use pressure bleeders now to minimize the risk of this happening. ok lets continue
          ************************
          6. once the pedal starts getting close to the floor, pedal pumper should alert the bleeder person to close it or signal them and say ok or something.
          7. close the bleeder valve. in any time that the bleeding is being performed, the pedal should not go up at all whether by operator or by some freak accident. basically the pedal should only be traveling downwards while the bleeder screw is open. it can be held in a certain point but as long as its not being released then its ok.
          8. repeat steps 5-7. and making sure to check and fill the reservoir as needed. and to lay the cap back down on the reservoir when performing the task

          once all done, double check each bleeder screw and make sure they are on tight (but not too tight or you'll be sorry). the clean them with some simple green or brake clean if u feel like it. top off brake fluid... replace the cap, tighten, and clean the reservoir and cap. test brake booster, start the car, and test feel of the pedal once its running to make sure that the pedal feel is maintained and does not sink to the floor. also check to make sure that there are no leaks. then test the brakes by driving the vehicle slowly forwards and backwards like in a driveway or something cuz u dont' have to move more than a few feet.

          *******
          if ppl got something to add or edit please do so. also the reason i do not loosen the bleeder screw then pump the brakes is cuz the "upwards motion of the brake pedal" will cause the MC to pull the fluid or anything up from the system (calipers and lines). this in effect will draw some fluid from the bleeder bottle or maybe even air done improperly.

          some say that they do it differently from me or even different from the manual, if it works and ur brakes hold fine then ok cool. but this is the only way i do it for my own vehicles or vehicles i work on.

          Comment


            #6
            Originally posted by Colin View Post
            You pretty much summed up a good starting point for this issue, I don't have much to add at all.

            I would IN NO WAY trust the reman master cylinder you purchased. Put that at the top of your list of possible causes for this problem. I can't even begin to tell you how many times I've had a carpart go bad only to replace it with a new (not oem) part which was bad out of the box or failed very soon after. This is the most frustrating thing in the world because you usually cross that item off of your list of possible culprits.

            Here is where I would start:

            1) Put the car on jackstands, make sure ALL brake components are extremely clean. STAND on the brakes with the engine off. Really build that pressure. Do this for awhile. Then immediately check ALL lines, fittings, connections... for any sign of leakage. If there is leakage, investigate it further.

            2) If there is no leak, drain the MC and remove it. Search for fluid leaking into the booster like Jeff mentioned. This isn't that uncommon. And that could explain you not seeing the fluid anywhere.

            Also, when you mentioned your brake bleeding method, I'm a bit confused as to exactly how you're doing it. Are you using example A or example B:

            Example A:
            1) Loosen bleed bolt
            2) Pump pedal to floor
            3) Tighten bleed screw
            4) Release pedal
            Repeat

            Example B:
            1) Loosen bleed bolt
            2) Pump pedal repeatedly
            3) Tighten bleed screw


            I also just realized that you have ABS. Unfortunately I'm not sure how that may or may not be effecting your situation. It shouldn't be, but there's always some off chance. ABS FTL.
            Already did step one, had the car off and I tried standing on that brake pedal to the point I thought I was going to cause a line to bust. No leaks that I could find, pressure is great when car is off, pedal is firm and doesn't go down much at all.

            Tomorrow I will get the master cylinder exchanged since it's covered by a lifetime warranty. It's free, so not a bad first option in terms of replacing parts since nothing else looks to be malfunctioning. Will also check in to the possibility of fluid leaking down in to the booster.

            I used Example B to bleed the brakes, as I always do. The hose is submerged in fresh brake fluid in a clear container I use for this purpose. Pedal is pumped repeatedly at a slow rate as to not make a mess. Fluid/bubbles go out, pure fluid comes back in...never had an issue with this method before. In fact, in the magazine Project Car / may & june of '08 issue, they have a walk-through on brake bleeding that is the same method I use. To clarify more for those that don't understand the method...

            1. Fiance in driver seat, me at whatever caliper I'm about to bleed.

            2. Attach 1 end of bleed hose to bleed screw, submerge other end of bleed hose in to container filled with fresh brake fluid.

            3. Open bleed screw.

            4. Fiance pumps brake pedal over and over, slowly.

            5. I watch the open end of the bleed hose that is submerged in fresh fluid in the container, old fluid/bubbles come out as she presses brake pedal, fresh fluid is sucked back in as the pedal goes up.

            6. She continues pumping brake pedal until I see no more bubbles coming out of the submerged end of the bleed hose, at that point I tell her to let off the brake and then I tighten the bleed screw.

            Due to the bleed hose being submerged the entire time, no air is allow to enter back in the brake system, only fluid.

            As for replacing the booster...it seems to be working fine at this point. Tomorrow I'll inspect it, and try the Haynes manual method of testing to make sure it's doing its job. A new one from autozone costs like 160, but does carry a lifetime warranty. Hopefully this doesn't need to be replaced yet.

            Comment


              #7
              Originally posted by Squeezethis View Post
              also the reason i do not loosen the bleeder screw then pump the brakes is cuz the "upwards motion of the brake pedal" will cause the MC to pull the fluid or anything up from the system (calipers and lines). this in effect will draw some fluid from the bleeder bottle or maybe even air done improperly.
              This is exactly what I do. When the pedal is going back up, fresh fluid is being pulled from the bleeder bottle...as long as the person doing the actual bleeding is making sure the end of the bleed hose stays submerged in the bottle at all times to keep air from being sucked in when the pedal is going up. I also make sure the bleed hose end isn't touching the bottom of the bottle, because it will suck up any dirty fluid and debris that shot out when the pedal was going down...the debris and dirty fluid tend to stay at the bottom of the bottle while the fresh fluid tends to stay at the top.

              Comment


                #8
                Jeff, your method is exactly the same as mine in regard to effectiveness. Your multiple pumps just build pressure (i think). I personally have always used a single pump. I've been bleeding brakes since I was a child. Yes, a child, when I was young my dad did a lot of SCCA and NASA racing. I was always the one who got to help him bleed the brakes

                You are correct about not letting it hit the floor. Supposedly this can wear out a master cylinder because it moves the piston further than it is used to on a normal everyday basis. This is only for old MC's though, a new one should be safe since all the seals are new.

                Sounds like the OP's method of submerging the end of the bleed line should prevent air from coming back up. So, having the pedal ascend and the bleed screw open I don't think would be a problem. But I've never done it that way.

                Comment


                  #9
                  Just bought a new master cylinder, a mityvac kit(because they kick ass and make the bleeding a 1person job), and some brake fluid.

                  So I get home, pulled the master cylinder off...fluid all over the lower front half of the brake booster and over that rear x-member/steering rack. Paint is peeling off the booster and the x-member. There's also signs that fluid has in fact gone in to the brake booster, the o-ring/gasket in the brake booster hole was wet with fluid, and the inner diameter of that hole had the black paint peeling from the lower half. This has definitely been a leak that has lasted probably since I did the master cylinder job 3 months ago, and definitely explains why the reservoir emptied.

                  So what does this mean exactly? Master cylinder is bad? Brake booster is bad? Both are bad?

                  EDIT: Is there supposed to be a gasket or seal on the piston end of the master cylinder around the piston, or just that rubber gasket in the brake booster hole? My current master cylinder doesn't have one, and the new master cylinder didn't come with one from a quick look in the box. When looking at that end of either master cylinder, around the piston is one of those metal snap-rings and nothing else. There is a weird rubber o-ring/gasket/seal type of thing that was in the brake booster hole, about the size of a half dollar give or take. There was a part number on it, and on one side it said "M/P SIDE". Is that the only gasket that should be there?
                  Last edited by DOHCIntegraLS; 13 Jun 2009, 18:12:03.

                  Comment


                    #10
                    Went ahead and wiped up all the leaked fluid, bench-bled the new master cylinder and installed it, bled all 4 calipers, topped off the reservoir and wiped down the master cylinder and brake booster again to get any spilled fluid I missed earlier so I could identify new leaks.

                    Test drove it about 1mile round trip, brakes work great. In fact they seem to be working better than they did after the last master cylinder replacement 3 months ago. I checked the bottom/front half of the brake booster and the underside of the master cylinder, no fluid. Drove the car to town, gassed it up, drove to taco bell, idled and ate my food, drove home...brakes still working great.

                    Looks like I just got a faulty remanufactured master cylinder from autozone. 1 out of the 4 or 5 I've purchased from them over the years is not bad I guess. Won't keep me from buying another unless this new one blows up anytime in the near future.

                    Comment


                      #11
                      thats great. glad u got it fixed man.

                      colin: ok i get ya when in regards with the piston n cups going so far down n stuf, maybe thats why i'm so cautious with brakes cuz i learned on a bunch of old cars. believe me when i say that i'd trust u to do brakes cuz i know that u've been doing stuff for a while. just converting it onto here just sounded off. so thats all

                      Comment


                        #12
                        oh and in regards to the end of the tube being submerged when bleeding. it will have air in the INITIAL process, of when the tube is hooked up to the bleeder valve. so right when u attach the hose to each bleeder screw. if u pump the brakes, then open the bleeder screw, and pump it some more while the bleeder screw is open...... it can draw any air that was within the tube, UNLESS u were able to force the air bubbles out into the tube. that is why a clear tube is crucial here.

                        basically......... when u pump the brakes........ b4 u even open the bleeder screw, the pumper should hold their foot down...... and never let that pedal come up even a lil bit until u close that bleeder valve. obviously ur method worked but just saying, to be very safe and all.

                        but now that i have had a few beers and ain't so sleepy, i understand colin's "method A" now........ open bleeder screw, pump the pedal down once...... close the screw. regarding method B and the OP's method, it sounds like its kinda pointless...... cuz u are moving the pistons back n forth thru an open system even tho the system is ending within the bleeder reservoir that he is using to inspect for bubbles at. cuz in a sense....... u can also drawback some crappy ass fluid thru there which has debris n stuff.

                        Comment


                          #13
                          That's pretty much the method I ended up using, the one you use. That's pretty much the same way you bleed a slave cylinder on a hydraulic trans.

                          I couldn't get the mityvac to work, maybe I understood the directions wrong. Basically this is what the directions had me do...

                          "Attach mityvac to reservoir cap using 1-1/2" of hose. Attach another hose 12" in length from reservoir cap to bleed screw. Attach 3" of hose to bottom of reservoir cap. Install reservoir to cap and tighten. Pump mityvac 10-15 times. Open bleed screw and let 2" of fluid accumulate in reservoir. Repeat previous steps on remaining calipers."

                          That's it, that's all the frickin' directions they gave me in this $30 kit. Kinda worthless so far. It has a million other uses, like testing for vacuum and applying vacuum, etc, so it may pay off with other jobs in the future I guess. As for brake bleeding I highly advise against using this, it's not air-tight at all at any of the connections. After 15 pumps, I watched the needle slowly crawl down on the mityvac gauge even though the caliper bleed screw was closed.

                          Comment


                            #14
                            lol. nah the pressure bleeder i use at work, just has to be plugged in to an a/c outlet (110). then u use some nice adapters for various reservoirs, find the right one, make sure its an air tight seal. then i use about 1.5 (dunno if its in bars or something). could be but not 100%. but yeah, u fill the big tank thing of brake fluid b4 u use it n stuff, and basically once its turned on, u go around and just open up the bleeder screws once u have a bottle and clear hose on it, then close them once u see good clear fluid coming thru with no more bubbles. then move to the next one. is a sick ass bleeder, i wanna get one, but it costs like $2k....... a bit out of my price range but its nice cuz its electrically powered. and the pump within it pressurizes the reservoir with brake fluid... so no air is introduced into it. and i never even have to monitor the brake reservoir on the car except when its initially turned on to make sure it doesn't leak.

                            Comment


                              #15
                              been gone from this thread for awhile, just glanced over the new posts but didn't really read too in depth... Looks like Jeff hit the nail on the head with this one about the MC leaking into the booster! Good call buddy! Glad to see that DOHC is on the right track again.

                              Comment


                                #16
                                Originally posted by Colin View Post
                                been gone from this thread for awhile, just glanced over the new posts but didn't really read too in depth... Looks like Jeff hit the nail on the head with this one about the MC leaking into the booster! Good call buddy! Glad to see that DOHC is on the right track again.
                                yea me too. its all good, i'm on here to help, just like u. besides, if i ain't helping i'm probably learning something.

                                Comment


                                  #17
                                  Originally posted by Squeezethis View Post
                                  yea me too. its all good, i'm on here to help, just like u. besides, if i ain't helping i'm probably learning something.
                                  You've got the right attitude

                                  Comment

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