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Brakes lockup, siezing with under bonnet heat

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  • e34535
    Hi, I am a new member and a BMW fan (tragic)from Australia, I have another e28 (aus delivered) among a stable of other BMW models (1x e34 535i manual,2x 3.0si,
    Message 1 of 11 , 20 Nov 17:53
      Hi, I am a new member and a BMW fan (tragic)from Australia, I have
      another e28 (aus delivered) among a stable of other BMW models (1x e34
      535i manual,2x 3.0si, 2x 3.0L) and have just bought at auction a UK
      spec 1986 e28, the car is low mileage (44000miles original with all
      books and service). I was wondering if anyone has had the problem this
      car is exhibiting before (my high mileage rather ragged aus spec e28
      has never given me any brake trouble like this). Being a UK spec the
      ATE hydraulic booster is on the drivers side(RHS above the exhaust
      manifold) - the aus spec car has the ATE booster on the LHS (US/Euro
      Left hand drive style)

      Problem: When I picked the car up I suspect it had been not used very
      regularly prior to its sale - brake discs showed no overheating, on
      driving it home I noticed that stuck in traffic the brakes started to
      squeal and bind - this got worse with a hard, high brake pedal(no real
      brake usage just stop start traffic) until the car was labouring
      against locked brakes, in 1st gear under full throttle to just keep
      moving. Bonnet up on roadside and many expletives/+*?@#%$_BMWs later
      I heard a series of metallic "clunks" from the area of the brake
      booster (this sound is easily heard inside the cabin), at this point
      the engine bay had started to cool down. I found then that the brakes
      had "let go" and the car could be driven again - until you applied the
      brakes (still some temperature in system)- lock up again - car can
      only be driven cold.

      Long story made short - 1. Had brakes professionally bled and took off
      that night to drive home (550kms) at country speeds (100km/h) - no
      brake troubles at all! (cold night/cool engine compartment) - thought
      it fixed, but next day same problem with engine heat again - bonnet
      up/ cool down / "clunk" / brakes free again ???

      Tested car by letting car heat up at idle for 15-20 minutes from cold
      (good pedal/brakes OK when cold), car not driven, no brake pedal use,
      result:- rock hard brake pedal again and locked brakes - placed trans
      in drive but car would not move at idle, ran cold water on the
      hydraulic brake booster(not master cylinder)and heard the light
      "clunks" brakes slowly let go in unison with "clunks" and car started
      to move under its own power.

      I am suspecting a faulty booster (or maybe Bomb/pressure unit), there
      is what appears to be a pressure valve on the return line on booster
      to the power steering reservoir - having never had the need or
      pleasure of dismantling a booster before I only guessing what is
      inside it.

      Has anyone had this problem before? - any help appreciated before a
      costly "suck it and see" replacement program is commenced. As I
      mentioned before the car is in 1st class condition for its 20 year
      vintage other than this problem.

      When things go wrong with an e28 they go WRONG! big time
    • John Forbey
      I don t know whether you will work on it yourself, but I say if it has nt been driven in a while the calipers may have gotten what I call water spot that make
      Message 2 of 11 , 20 Nov 21:18
        I don't know whether you will work on it yourself, but
        I say if it has'nt been driven in a while the calipers
        may have gotten what I call water spot that make them
        bind. Take the calipers off and they have screws that
        allow you to separate the halves. You can buy kits
        pretty easy, maybe price online dealers to find
        rebuild kits to replace the o-ring seals. There will
        be an expanding rubber cup that seals the piston and
        clasps around with wire clip. Clean the parts well
        and make sure no rust. Use silicon brake fluid to
        lubricate parts, seals before assy. This is just a
        start; but if it has'nt driven in while may be what
        needs to be done.
        John F. Forbey
        jforbey@...
        --- e34535 <e34535@...> wrote:

        > Hi, I am a new member and a BMW fan (tragic)from
        > Australia, I have
        > another e28 (aus delivered) among a stable of other
        > BMW models (1x e34
        > 535i manual,2x 3.0si, 2x 3.0L) and have just bought
        > at auction a UK
        > spec 1986 e28, the car is low mileage (44000miles
        > original with all
        > books and service). I was wondering if anyone has
        > had the problem this
        > car is exhibiting before (my high mileage rather
        > ragged aus spec e28
        > has never given me any brake trouble like this).
        > Being a UK spec the
        > ATE hydraulic booster is on the drivers side(RHS
        > above the exhaust
        > manifold) - the aus spec car has the ATE booster on
        > the LHS (US/Euro
        > Left hand drive style)
        >
        > Problem: When I picked the car up I suspect it had
        > been not used very
        > regularly prior to its sale - brake discs showed no
        > overheating, on
        > driving it home I noticed that stuck in traffic the
        > brakes started to
        > squeal and bind - this got worse with a hard, high
        > brake pedal(no real
        > brake usage just stop start traffic) until the car
        > was labouring
        > against locked brakes, in 1st gear under full
        > throttle to just keep
        > moving. Bonnet up on roadside and many
        > expletives/+*?@#%$_BMWs later
        > I heard a series of metallic "clunks" from the area
        > of the brake
        > booster (this sound is easily heard inside the
        > cabin), at this point
        > the engine bay had started to cool down. I found
        > then that the brakes
        > had "let go" and the car could be driven again -
        > until you applied the
        > brakes (still some temperature in system)- lock up
        > again - car can
        > only be driven cold.
        >
        > Long story made short - 1. Had brakes professionally
        > bled and took off
        > that night to drive home (550kms) at country speeds
        > (100km/h) - no
        > brake troubles at all! (cold night/cool engine
        > compartment) - thought
        > it fixed, but next day same problem with engine heat
        > again - bonnet
        > up/ cool down / "clunk" / brakes free again ???
        >
        > Tested car by letting car heat up at idle for 15-20
        > minutes from cold
        > (good pedal/brakes OK when cold), car not driven, no
        > brake pedal use,
        > result:- rock hard brake pedal again and locked
        > brakes - placed trans
        > in drive but car would not move at idle, ran cold
        > water on the
        > hydraulic brake booster(not master cylinder)and
        > heard the light
        > "clunks" brakes slowly let go in unison with
        > "clunks" and car started
        > to move under its own power.
        >
        > I am suspecting a faulty booster (or maybe
        > Bomb/pressure unit), there
        > is what appears to be a pressure valve on the return
        > line on booster
        > to the power steering reservoir - having never had
        > the need or
        > pleasure of dismantling a booster before I only
        > guessing what is
        > inside it.
        >
        > Has anyone had this problem before? - any help
        > appreciated before a
        > costly "suck it and see" replacement program is
        > commenced. As I
        > mentioned before the car is in 1st class condition
        > for its 20 year
        > vintage other than this problem.
        >
        > When things go wrong with an e28 they go WRONG! big
        > time
        >
        >
        >




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      • e34535
        ... Hi John Thanks for the reply, I sort of dismissed the calipers as a problem area as the car stops like a shot duck when everything is cold - as I mentioned
        Message 3 of 11 , 21 Nov 17:27
          --- In bmwe28@..., John Forbey <jforbey@...> wrote:
          >

          Hi John
          Thanks for the reply, I sort of dismissed the calipers as a problem
          area as the car stops like a shot duck when everything is cold - as I
          mentioned I tested it with just idling the car for approx 20 minutes,
          the brakes/calipers were stone cold but the engine bay was hot - and
          the problem reoccurred. This leads me to the fact that some "heat
          sink" effect to a brake component in the engine bay is actuating the
          brakes and locking them on . Maybe a pressure build up in the brake
          hydraulic booster system with no pressure relief possible - something
          is possibly causing the master cylinder to actuate and not return as
          it would normally when you apply the brakes and then take your foot
          off e.g maybe the brake booster is pushing the master cylinder rod in
          under its own power and locking on the brakes. WIIEERRD !! - (stands
          at front of car, chants and holds up wooden cross as he opens the
          bonnet again)

          >
        • Steve Haygood
          We have seen the brake master cause this as well Steve Steve Haygood BMW CCA 6 Series Register Director 03/04/05 Official 5er Fest Sponsor 03/04/05 Official
          Message 4 of 11 , 21 Nov 18:38
            We have seen the brake master cause this as well
            Steve

            Steve Haygood
            BMW CCA 6 Series Register Director
            03/04/05 Official 5er Fest Sponsor
            03/04/05 Official Sharkfest Sponsor
            www.stevehaygood.com


            _____

            From: bmwe28@... [mailto:bmwe28@...] On Behalf
            Of e34535
            Sent: Tuesday, November 21, 2006 8:27 PM
            To: bmwe28@...
            Subject: Re: [bmw e28] Brakes lockup, siezing with under bonnet heat



            --- In bmwe28@yahoogroups. <mailto:bmwe28%40yahoogroups.co.uk> co.uk, John
            Forbey <jforbey@...> wrote:
            >

            Hi John
            Thanks for the reply, I sort of dismissed the calipers as a problem
            area as the car stops like a shot duck when everything is cold - as I
            mentioned I tested it with just idling the car for approx 20 minutes,
            the brakes/calipers were stone cold but the engine bay was hot - and
            the problem reoccurred. This leads me to the fact that some "heat
            sink" effect to a brake component in the engine bay is actuating the
            brakes and locking them on . Maybe a pressure build up in the brake
            hydraulic booster system with no pressure relief possible - something
            is possibly causing the master cylinder to actuate and not return as
            it would normally when you apply the brakes and then take your foot
            off e.g maybe the brake booster is pushing the master cylinder rod in
            under its own power and locking on the brakes. WIIEERRD !! - (stands
            at front of car, chants and holds up wooden cross as he opens the
            bonnet again)

            >






            [Non-text portions of this message have been removed]
          • e34535
            Hi Steve Brake master cylinder possibly, but the funny thing is that apparently under its own accord the brakes apply themselves and lock on as the underbonnet
            Message 5 of 11 , 21 Nov 19:08
              Hi Steve
              Brake master cylinder possibly, but the funny thing is that apparently
              under its own accord the brakes apply themselves and lock on as the
              underbonnet temperature rises - no brake application/motor idling and
              car stationary/cold calipers and discs - just start the car from cold
              and let it stand there and on go the brakes slowly as the underbonnet
              heat goes up. At this point there is not a lot of heat in the
              booster/master unit, hot to the touch Playing water from a hose on
              the booster area releases the brakes in a short time with metallic clunks.
              Kevin
              (how could such a nice looking car have such a personality disorder -
              a bit like an ex girlfriend!)
            • Steve Haygood
              In, in that case, looks like the booster, Let me know if you want pricing on a new one... Steve Steve Haygood BMW CCA 6 Series Register Director 03/04/05
              Message 6 of 11 , 21 Nov 19:46
                In, in that case, looks like the booster, Let me know if you want pricing on
                a new one...
                Steve

                Steve Haygood
                BMW CCA 6 Series Register Director
                03/04/05 Official 5er Fest Sponsor
                03/04/05 Official Sharkfest Sponsor
                www.stevehaygood.com


                _____

                From: bmwe28@... [mailto:bmwe28@...] On Behalf
                Of e34535
                Sent: Tuesday, November 21, 2006 10:09 PM
                To: bmwe28@...
                Subject: Re: [bmw e28] Brakes lockup, siezing with under bonnet heat




                Hi Steve
                Brake master cylinder possibly, but the funny thing is that apparently
                under its own accord the brakes apply themselves and lock on as the
                underbonnet temperature rises - no brake application/motor idling and
                car stationary/cold calipers and discs - just start the car from cold
                and let it stand there and on go the brakes slowly as the underbonnet
                heat goes up. At this point there is not a lot of heat in the
                booster/master unit, hot to the touch Playing water from a hose on
                the booster area releases the brakes in a short time with metallic clunks.
                Kevin
                (how could such a nice looking car have such a personality disorder -
                a bit like an ex girlfriend!)






                [Non-text portions of this message have been removed]
              • John Forbey
                Is this car s system with a accumulator ball under the brake master? jforbey@yahoo.com ...
                Message 7 of 11 , 21 Nov 20:07
                  Is this car's system with a accumulator ball under the
                  brake master?
                  jforbey@...
                  --- Steve Haygood <sfhaygood@...> wrote:

                  > We have seen the brake master cause this as well
                  > Steve
                  >
                  > Steve Haygood
                  > BMW CCA 6 Series Register Director
                  > 03/04/05 Official 5er Fest Sponsor
                  > 03/04/05 Official Sharkfest Sponsor
                  > www.stevehaygood.com
                  >
                  >
                  > _____
                  >
                  > From: bmwe28@...
                  > [mailto:bmwe28@...] On Behalf
                  > Of e34535
                  > Sent: Tuesday, November 21, 2006 8:27 PM
                  > To: bmwe28@...
                  > Subject: Re: [bmw e28] Brakes lockup, siezing with
                  > under bonnet heat
                  >
                  >
                  >
                  > --- In bmwe28@yahoogroups.
                  > <mailto:bmwe28%40yahoogroups.co.uk> co.uk, John
                  > Forbey <jforbey@...> wrote:
                  > >
                  >
                  > Hi John
                  > Thanks for the reply, I sort of dismissed the
                  > calipers as a problem
                  > area as the car stops like a shot duck when
                  > everything is cold - as I
                  > mentioned I tested it with just idling the car for
                  > approx 20 minutes,
                  > the brakes/calipers were stone cold but the engine
                  > bay was hot - and
                  > the problem reoccurred. This leads me to the fact
                  > that some "heat
                  > sink" effect to a brake component in the engine bay
                  > is actuating the
                  > brakes and locking them on . Maybe a pressure build
                  > up in the brake
                  > hydraulic booster system with no pressure relief
                  > possible - something
                  > is possibly causing the master cylinder to actuate
                  > and not return as
                  > it would normally when you apply the brakes and then
                  > take your foot
                  > off e.g maybe the brake booster is pushing the
                  > master cylinder rod in
                  > under its own power and locking on the brakes.
                  > WIIEERRD !! - (stands
                  > at front of car, chants and holds up wooden cross as
                  > he opens the
                  > bonnet again)
                  >
                  > >
                  >
                  >
                  >
                  >
                  >
                  >
                  > [Non-text portions of this message have been
                  > removed]
                  >
                  >




                  ____________________________________________________________________________________
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                  Online or Campus degree Associate's, Bachelor's, or Master's
                  in less than one year.www.findtherightschool.com
                • Gil Thereault
                  I agree with Steve. I had the same problem with the right front caliper locking up. I thought it was the heat. I replaced the master cylinder. Problem was
                  Message 8 of 11 , 21 Nov 21:51
                    I agree with Steve. I had the same problem with the right front caliper locking up. I thought it was the heat. I replaced the master cylinder. Problem was solved back in 2001.

                    Gil
                    86 535i 192k

                    John Forbey <jforbey@...> wrote:
                    Is this car's system with a accumulator ball under the
                    brake master?
                    jforbey@...
                    --- Steve Haygood <sfhaygood@...> wrote:

                    > We have seen the brake master cause this as well
                    > Steve
                    >
                    > Steve Haygood
                    > BMW CCA 6 Series Register Director
                    > 03/04/05 Official 5er Fest Sponsor
                    > 03/04/05 Official Sharkfest Sponsor
                    > www.stevehaygood.com
                    >
                    >
                    > _____
                    >
                    > From: bmwe28@...
                    > [mailto:bmwe28@...] On Behalf
                    > Of e34535
                    > Sent: Tuesday, November 21, 2006 8:27 PM
                    > To: bmwe28@...
                    > Subject: Re: [bmw e28] Brakes lockup, siezing with
                    > under bonnet heat
                    >
                    >
                    >
                    > --- In bmwe28@yahoogroups.
                    > <mailto:bmwe28%40yahoogroups.co.uk> co.uk, John
                    > Forbey <jforbey@...> wrote:
                    > >
                    >
                    > Hi John
                    > Thanks for the reply, I sort of dismissed the
                    > calipers as a problem
                    > area as the car stops like a shot duck when
                    > everything is cold - as I
                    > mentioned I tested it with just idling the car for
                    > approx 20 minutes,
                    > the brakes/calipers were stone cold but the engine
                    > bay was hot - and
                    > the problem reoccurred. This leads me to the fact
                    > that some "heat
                    > sink" effect to a brake component in the engine bay
                    > is actuating the
                    > brakes and locking them on . Maybe a pressure build
                    > up in the brake
                    > hydraulic booster system with no pressure relief
                    > possible - something
                    > is possibly causing the master cylinder to actuate
                    > and not return as
                    > it would normally when you apply the brakes and then
                    > take your foot
                    > off e.g maybe the brake booster is pushing the
                    > master cylinder rod in
                    > under its own power and locking on the brakes.
                    > WIIEERRD !! - (stands
                    > at front of car, chants and holds up wooden cross as
                    > he opens the
                    > bonnet again)
                    >
                    > >
                    >
                    >
                    >
                    >
                    >
                    >
                    > [Non-text portions of this message have been
                    > removed]
                    >
                    >

                    __________________________________________________________
                    Sponsored Link

                    Online or Campus degree Associate's, Bachelor's, or Master's
                    in less than one year.www.findtherightschool.com





                    ---------------------------------
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                    [Non-text portions of this message have been removed]
                  • Gil Thereault
                    Hello All, From my past experience, the high hard brake pedal issue is the brake accumulator. I have replaced mine twice in the past six years. You may have
                    Message 9 of 11 , 21 Nov 22:29
                      Hello All,

                      From my past experience, the high hard brake pedal issue is the brake accumulator. I have replaced mine twice in the past six years. You may have an issue with the regulator ?? from the noise you have described or it could have been due to the high temperature of the brake fluid in the regulator from the overheating of the rotor and caliper. I too have replaced the master cylinder as I also was experiencing the right front caliper locking up. I thought it was from the heat as well. I learned this after needless swapping out a good functional right front caliper. Do these things first (the easy things) then go further to the calipers and/ or the regulator.

                      Gil
                      86 535i 192k



                      John Forbey <jforbey@...> wrote:
                      I don't know whether you will work on it yourself, but
                      I say if it has'nt been driven in a while the calipers
                      may have gotten what I call water spot that make them
                      bind. Take the calipers off and they have screws that
                      allow you to separate the halves. You can buy kits
                      pretty easy, maybe price online dealers to find
                      rebuild kits to replace the o-ring seals. There will
                      be an expanding rubber cup that seals the piston and
                      clasps around with wire clip. Clean the parts well
                      and make sure no rust. Use silicon brake fluid to
                      lubricate parts, seals before assy. This is just a
                      start; but if it has'nt driven in while may be what
                      needs to be done.
                      John F. Forbey
                      jforbey@...
                      --- e34535 <e34535@...> wrote:

                      > Hi, I am a new member and a BMW fan (tragic)from
                      > Australia, I have
                      > another e28 (aus delivered) among a stable of other
                      > BMW models (1x e34
                      > 535i manual,2x 3.0si, 2x 3.0L) and have just bought
                      > at auction a UK
                      > spec 1986 e28, the car is low mileage (44000miles
                      > original with all
                      > books and service). I was wondering if anyone has
                      > had the problem this
                      > car is exhibiting before (my high mileage rather
                      > ragged aus spec e28
                      > has never given me any brake trouble like this).
                      > Being a UK spec the
                      > ATE hydraulic booster is on the drivers side(RHS
                      > above the exhaust
                      > manifold) - the aus spec car has the ATE booster on
                      > the LHS (US/Euro
                      > Left hand drive style)
                      >
                      > Problem: When I picked the car up I suspect it had
                      > been not used very
                      > regularly prior to its sale - brake discs showed no
                      > overheating, on
                      > driving it home I noticed that stuck in traffic the
                      > brakes started to
                      > squeal and bind - this got worse with a hard, high
                      > brake pedal(no real
                      > brake usage just stop start traffic) until the car
                      > was labouring
                      > against locked brakes, in 1st gear under full
                      > throttle to just keep
                      > moving. Bonnet up on roadside and many
                      > expletives/+*?@#%$_BMWs later
                      > I heard a series of metallic "clunks" from the area
                      > of the brake
                      > booster (this sound is easily heard inside the
                      > cabin), at this point
                      > the engine bay had started to cool down. I found
                      > then that the brakes
                      > had "let go" and the car could be driven again -
                      > until you applied the
                      > brakes (still some temperature in system)- lock up
                      > again - car can
                      > only be driven cold.
                      >
                      > Long story made short - 1. Had brakes professionally
                      > bled and took off
                      > that night to drive home (550kms) at country speeds
                      > (100km/h) - no
                      > brake troubles at all! (cold night/cool engine
                      > compartment) - thought
                      > it fixed, but next day same problem with engine heat
                      > again - bonnet
                      > up/ cool down / "clunk" / brakes free again ???
                      >
                      > Tested car by letting car heat up at idle for 15-20
                      > minutes from cold
                      > (good pedal/brakes OK when cold), car not driven, no
                      > brake pedal use,
                      > result:- rock hard brake pedal again and locked
                      > brakes - placed trans
                      > in drive but car would not move at idle, ran cold
                      > water on the
                      > hydraulic brake booster(not master cylinder)and
                      > heard the light
                      > "clunks" brakes slowly let go in unison with
                      > "clunks" and car started
                      > to move under its own power.
                      >
                      > I am suspecting a faulty booster (or maybe
                      > Bomb/pressure unit), there
                      > is what appears to be a pressure valve on the return
                      > line on booster
                      > to the power steering reservoir - having never had
                      > the need or
                      > pleasure of dismantling a booster before I only
                      > guessing what is
                      > inside it.
                      >
                      > Has anyone had this problem before? - any help
                      > appreciated before a
                      > costly "suck it and see" replacement program is
                      > commenced. As I
                      > mentioned before the car is in 1st class condition
                      > for its 20 year
                      > vintage other than this problem.
                      >
                      > When things go wrong with an e28 they go WRONG! big
                      > time
                      >
                      >
                      >

                      __________________________________________________________
                      Sponsored Link

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                      Think You Pay Too Much For Your Mortgage?
                      Find Out! www.LowerMyBills.com/lre





                      ---------------------------------
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                      [Non-text portions of this message have been removed]
                    • e34535
                      ... evidence for you. I inspected car thoroughly before auction to check for signs that it was not an original garaged 44000 miles vehicle - all points backed
                      Message 10 of 11 , 22 Nov 04:47
                        --- In bmwe28@..., Gil Thereault <giln1oiw2001@...> wrote:
                        >Hi Gil,John and Steve Thanks for the posts guy - a little more
                        evidence for you.
                        I inspected car thoroughly before auction to check for signs that it
                        was not an original garaged 44000 miles vehicle - all points backed up
                        the claim, service books would indicate little use over the last
                        couple of years. Disc rotors showed NO signs of any heat effects at
                        all, at this time - drove/stopped (when cold) beautifully on auction
                        test drive. Problem raised its head in traffic after leaving the
                        auction house - when I got the car off the road all 4 discs were
                        smoking and blue. When the brakes "let go" on cooling, all 4 let go
                        together(so I am thinking what ever is doing it is affecting all 4
                        discs at once, and probably both brake circuits - (when these babies
                        lock on( this happens progressively not suddenly) its back to 1st gear
                        (auto), foot flat to the floor/maximum load on the motor/box to creep
                        along at walking pace. Obviously this no way to treat a lady, as
                        mentioned, if you then lift bonnet and wait maybe 10-15 minutes
                        cooling the engine bay down the brakes will slowly release (all 4). I
                        have had on one occassion, the brakes suddenly release (with a "clunk"
                        from the vicinity of the booster while I had my foot flat to the floor
                        against the brakes looking for a pull off spot (very interesting
                        effect - like stalling up on the drag strip and sliding your foot off
                        the brake pedal - BANG and we are away). I could maybe see problems
                        from boiling brake fluid/calipers siezing when hot/overheated
                        hydraulic fluid on the booster power side, BUT,and it is a big BUT, As
                        mentioned I have tested it on cold start ups, brakes fine (roll car by
                        hand, no binding, cold brakes/calipers/fluid (has had 2 brake bleeds
                        now)/cold discs etc., and by the time the car has reached operating
                        temp you cannot roll the car by hand , and in 15mins you cannot drive
                        off at all. Lift bonnet at this time and hose only the booster with
                        water and brakes will gradually let go (hosing the
                        accumulator/pressure block and the master cylinder do not have any
                        effect). Looks like it may be a surgical strike is called for
                        (disembowlment of booster for starters). Would a faulty accumulator
                        produce a hard high pedal all the time it is pressurised or be
                        affected by heat?

                        This car is starting to look like a reinCARnation of an old girlfriend
                        - well kept, low mileage, great upholstery, tight suspension, but
                        temperamental,with a personality (suspect) all of its own - and puts
                        the brakes on hard just when your starting to enjoy it!
                        Kevin

                        > Hello All,
                        >
                        > From my past experience, the high hard brake pedal issue is the
                        brake accumulator. I have replaced mine twice in the past six years.
                        You may have an issue with the regulator ?? from the noise you have
                        described or it could have been due to the high temperature of the
                        brake fluid in the regulator from the overheating of the rotor and
                        caliper. I too have replaced the master cylinder as I also was
                        experiencing the right front caliper locking up. I thought it was
                        from the heat as well. I learned this after needless swapping out a
                        good functional right front caliper. Do these things first (the easy
                        things) then go further to the calipers and/ or the regulator.
                        >
                        > Gil
                        > 86 535i 192k
                        >
                        >
                        >
                        > John Forbey <jforbey@...> wrote:
                        > I don't know whether you will work on it yourself, but
                        > I say if it has'nt been driven in a while the calipers
                        > may have gotten what I call water spot that make them
                        > bind. Take the calipers off and they have screws that
                        > allow you to separate the halves. You can buy kits
                        > pretty easy, maybe price online dealers to find
                        > rebuild kits to replace the o-ring seals. There will
                        > be an expanding rubber cup that seals the piston and
                        > clasps around with wire clip. Clean the parts well
                        > and make sure no rust. Use silicon brake fluid to
                        > lubricate parts, seals before assy. This is just a
                        > start; but if it has'nt driven in while may be what
                        > needs to be done.
                        > John F. Forbey
                        > jforbey@...
                        > --- e34535 <e34535@...> wrote:
                        >
                        > > Hi, I am a new member and a BMW fan (tragic)from
                        > > Australia, I have
                        > > another e28 (aus delivered) among a stable of other
                        > > BMW models (1x e34
                        > > 535i manual,2x 3.0si, 2x 3.0L) and have just bought
                        > > at auction a UK
                        > > spec 1986 e28, the car is low mileage (44000miles
                        > > original with all
                        > > books and service). I was wondering if anyone has
                        > > had the problem this
                        > > car is exhibiting before (my high mileage rather
                        > > ragged aus spec e28
                        > > has never given me any brake trouble like this).
                        > > Being a UK spec the
                        > > ATE hydraulic booster is on the drivers side(RHS
                        > > above the exhaust
                        > > manifold) - the aus spec car has the ATE booster on
                        > > the LHS (US/Euro
                        > > Left hand drive style)
                        > >
                        > > Problem: When I picked the car up I suspect it had
                        > > been not used very
                        > > regularly prior to its sale - brake discs showed no
                        > > overheating, on
                        > > driving it home I noticed that stuck in traffic the
                        > > brakes started to
                        > > squeal and bind - this got worse with a hard, high
                        > > brake pedal(no real
                        > > brake usage just stop start traffic) until the car
                        > > was labouring
                        > > against locked brakes, in 1st gear under full
                        > > throttle to just keep
                        > > moving. Bonnet up on roadside and many
                        > > expletives/+*?@#%$_BMWs later
                        > > I heard a series of metallic "clunks" from the area
                        > > of the brake
                        > > booster (this sound is easily heard inside the
                        > > cabin), at this point
                        > > the engine bay had started to cool down. I found
                        > > then that the brakes
                        > > had "let go" and the car could be driven again -
                        > > until you applied the
                        > > brakes (still some temperature in system)- lock up
                        > > again - car can
                        > > only be driven cold.
                        > >
                        > > Long story made short - 1. Had brakes professionally
                        > > bled and took off
                        > > that night to drive home (550kms) at country speeds
                        > > (100km/h) - no
                        > > brake troubles at all! (cold night/cool engine
                        > > compartment) - thought
                        > > it fixed, but next day same problem with engine heat
                        > > again - bonnet
                        > > up/ cool down / "clunk" / brakes free again ???
                        > >
                        > > Tested car by letting car heat up at idle for 15-20
                        > > minutes from cold
                        > > (good pedal/brakes OK when cold), car not driven, no
                        > > brake pedal use,
                        > > result:- rock hard brake pedal again and locked
                        > > brakes - placed trans
                        > > in drive but car would not move at idle, ran cold
                        > > water on the
                        > > hydraulic brake booster(not master cylinder)and
                        > > heard the light
                        > > "clunks" brakes slowly let go in unison with
                        > > "clunks" and car started
                        > > to move under its own power.
                        > >
                        > > I am suspecting a faulty booster (or maybe
                        > > Bomb/pressure unit), there
                        > > is what appears to be a pressure valve on the return
                        > > line on booster
                        > > to the power steering reservoir - having never had
                        > > the need or
                        > > pleasure of dismantling a booster before I only
                        > > guessing what is
                        > > inside it.
                        > >
                        > > Has anyone had this problem before? - any help
                        > > appreciated before a
                        > > costly "suck it and see" replacement program is
                        > > commenced. As I
                        > > mentioned before the car is in 1st class condition
                        > > for its 20 year
                        > > vintage other than this problem.
                        > >
                        > > When things go wrong with an e28 they go WRONG! big
                        > > time
                        > >
                        > >
                        > >
                        >
                        > __________________________________________________________
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                        >
                        >
                        >
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                        > [Non-text portions of this message have been removed]
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                      • e34535
                        Hi guys found the problem with siezing brakes - it turns out that the master cylinder is cast iron on this model not aluminium, removed master cyl and warmed
                        Message 11 of 11 , Mar 7, 2007
                          Hi guys found the problem with siezing brakes - it turns out that the
                          master cylinder is cast iron on this model not aluminium, removed
                          master cyl and warmed it up in oven and the cylinder siezes - could
                          either be distortion in the body or the bore grabbing on the piston -
                          cut a long story short - replaced master cyl with alloy version,
                          rerouted the pipes to the new connection positions and no more siezing
                          - wierd!

                          --- In bmwe28@..., "e34535" <e34535@...> wrote:
                          >
                          > --- In bmwe28@..., Gil Thereault <giln1oiw2001@> wrote:
                          > >Hi Gil,John and Steve Thanks for the posts guy - a little more
                          > evidence for you.
                          > I inspected car thoroughly before auction to check for signs that it
                          > was not an original garaged 44000 miles vehicle - all points backed up
                          > the claim, service books would indicate little use over the last
                          > couple of years. Disc rotors showed NO signs of any heat effects at
                          > all, at this time - drove/stopped (when cold) beautifully on auction
                          > test drive. Problem raised its head in traffic after leaving the
                          > auction house - when I got the car off the road all 4 discs were
                          > smoking and blue. When the brakes "let go" on cooling, all 4 let go
                          > together(so I am thinking what ever is doing it is affecting all 4
                          > discs at once, and probably both brake circuits - (when these babies
                          > lock on( this happens progressively not suddenly) its back to 1st gear
                          > (auto), foot flat to the floor/maximum load on the motor/box to creep
                          > along at walking pace. Obviously this no way to treat a lady, as
                          > mentioned, if you then lift bonnet and wait maybe 10-15 minutes
                          > cooling the engine bay down the brakes will slowly release (all 4). I
                          > have had on one occassion, the brakes suddenly release (with a "clunk"
                          > from the vicinity of the booster while I had my foot flat to the floor
                          > against the brakes looking for a pull off spot (very interesting
                          > effect - like stalling up on the drag strip and sliding your foot off
                          > the brake pedal - BANG and we are away). I could maybe see problems
                          > from boiling brake fluid/calipers siezing when hot/overheated
                          > hydraulic fluid on the booster power side, BUT,and it is a big BUT, As
                          > mentioned I have tested it on cold start ups, brakes fine (roll car by
                          > hand, no binding, cold brakes/calipers/fluid (has had 2 brake bleeds
                          > now)/cold discs etc., and by the time the car has reached operating
                          > temp you cannot roll the car by hand , and in 15mins you cannot drive
                          > off at all. Lift bonnet at this time and hose only the booster with
                          > water and brakes will gradually let go (hosing the
                          > accumulator/pressure block and the master cylinder do not have any
                          > effect). Looks like it may be a surgical strike is called for
                          > (disembowlment of booster for starters). Would a faulty accumulator
                          > produce a hard high pedal all the time it is pressurised or be
                          > affected by heat?
                          >
                          > This car is starting to look like a reinCARnation of an old girlfriend
                          > - well kept, low mileage, great upholstery, tight suspension, but
                          > temperamental,with a personality (suspect) all of its own - and puts
                          > the brakes on hard just when your starting to enjoy it!
                          > Kevin
                          >
                          > > Hello All,
                          > >
                          > > From my past experience, the high hard brake pedal issue is the
                          > brake accumulator. I have replaced mine twice in the past six years.
                          > You may have an issue with the regulator ?? from the noise you have
                          > described or it could have been due to the high temperature of the
                          > brake fluid in the regulator from the overheating of the rotor and
                          > caliper. I too have replaced the master cylinder as I also was
                          > experiencing the right front caliper locking up. I thought it was
                          > from the heat as well. I learned this after needless swapping out a
                          > good functional right front caliper. Do these things first (the easy
                          > things) then go further to the calipers and/ or the regulator.
                          > >
                          > > Gil
                          > > 86 535i 192k
                          > >
                          > >
                          > >
                          > > John Forbey <jforbey@> wrote:
                          > > I don't know whether you will work on it yourself, but
                          > > I say if it has'nt been driven in a while the calipers
                          > > may have gotten what I call water spot that make them
                          > > bind. Take the calipers off and they have screws that
                          > > allow you to separate the halves. You can buy kits
                          > > pretty easy, maybe price online dealers to find
                          > > rebuild kits to replace the o-ring seals. There will
                          > > be an expanding rubber cup that seals the piston and
                          > > clasps around with wire clip. Clean the parts well
                          > > and make sure no rust. Use silicon brake fluid to
                          > > lubricate parts, seals before assy. This is just a
                          > > start; but if it has'nt driven in while may be what
                          > > needs to be done.
                          > > John F. Forbey
                          > > jforbey@
                          > > --- e34535 <e34535@> wrote:
                          > >
                          > > > Hi, I am a new member and a BMW fan (tragic)from
                          > > > Australia, I have
                          > > > another e28 (aus delivered) among a stable of other
                          > > > BMW models (1x e34
                          > > > 535i manual,2x 3.0si, 2x 3.0L) and have just bought
                          > > > at auction a UK
                          > > > spec 1986 e28, the car is low mileage (44000miles
                          > > > original with all
                          > > > books and service). I was wondering if anyone has
                          > > > had the problem this
                          > > > car is exhibiting before (my high mileage rather
                          > > > ragged aus spec e28
                          > > > has never given me any brake trouble like this).
                          > > > Being a UK spec the
                          > > > ATE hydraulic booster is on the drivers side(RHS
                          > > > above the exhaust
                          > > > manifold) - the aus spec car has the ATE booster on
                          > > > the LHS (US/Euro
                          > > > Left hand drive style)
                          > > >
                          > > > Problem: When I picked the car up I suspect it had
                          > > > been not used very
                          > > > regularly prior to its sale - brake discs showed no
                          > > > overheating, on
                          > > > driving it home I noticed that stuck in traffic the
                          > > > brakes started to
                          > > > squeal and bind - this got worse with a hard, high
                          > > > brake pedal(no real
                          > > > brake usage just stop start traffic) until the car
                          > > > was labouring
                          > > > against locked brakes, in 1st gear under full
                          > > > throttle to just keep
                          > > > moving. Bonnet up on roadside and many
                          > > > expletives/+*?@#%$_BMWs later
                          > > > I heard a series of metallic "clunks" from the area
                          > > > of the brake
                          > > > booster (this sound is easily heard inside the
                          > > > cabin), at this point
                          > > > the engine bay had started to cool down. I found
                          > > > then that the brakes
                          > > > had "let go" and the car could be driven again -
                          > > > until you applied the
                          > > > brakes (still some temperature in system)- lock up
                          > > > again - car can
                          > > > only be driven cold.
                          > > >
                          > > > Long story made short - 1. Had brakes professionally
                          > > > bled and took off
                          > > > that night to drive home (550kms) at country speeds
                          > > > (100km/h) - no
                          > > > brake troubles at all! (cold night/cool engine
                          > > > compartment) - thought
                          > > > it fixed, but next day same problem with engine heat
                          > > > again - bonnet
                          > > > up/ cool down / "clunk" / brakes free again ???
                          > > >
                          > > > Tested car by letting car heat up at idle for 15-20
                          > > > minutes from cold
                          > > > (good pedal/brakes OK when cold), car not driven, no
                          > > > brake pedal use,
                          > > > result:- rock hard brake pedal again and locked
                          > > > brakes - placed trans
                          > > > in drive but car would not move at idle, ran cold
                          > > > water on the
                          > > > hydraulic brake booster(not master cylinder)and
                          > > > heard the light
                          > > > "clunks" brakes slowly let go in unison with
                          > > > "clunks" and car started
                          > > > to move under its own power.
                          > > >
                          > > > I am suspecting a faulty booster (or maybe
                          > > > Bomb/pressure unit), there
                          > > > is what appears to be a pressure valve on the return
                          > > > line on booster
                          > > > to the power steering reservoir - having never had
                          > > > the need or
                          > > > pleasure of dismantling a booster before I only
                          > > > guessing what is
                          > > > inside it.
                          > > >
                          > > > Has anyone had this problem before? - any help
                          > > > appreciated before a
                          > > > costly "suck it and see" replacement program is
                          > > > commenced. As I
                          > > > mentioned before the car is in 1st class condition
                          > > > for its 20 year
                          > > > vintage other than this problem.
                          > > >
                          > > > When things go wrong with an e28 they go WRONG! big
                          > > > time
                          > > >
                          > > >
                          > > >
                          > >
                          > > __________________________________________________________
                          > > Sponsored Link
                          > >
                          > > $420k for $1,399/mo.
                          > > Think You Pay Too Much For Your Mortgage?
                          > > Find Out! www.LowerMyBills.com/lre
                          > >
                          > >
                          > >
                          > >
                          > >
                          > > ---------------------------------
                          > > Sponsored Link
                          > >
                          > > Degrees for employed people - in as fast as 1 year. A.S. / Bachelors
                          > / Masters
                          > >
                          > > [Non-text portions of this message have been removed]
                          > >
                          >
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