1987 BMW 325E Brake Pressure Build Up

<Oscar.DeleteThis@nowhere.com> wrote in message
news:tskb5393tf5tbmntns6qepst34fqr48nh5@4ax.com...
> On 24 May 2007 07:49:04 -0700, cbwillia0605.DeleteThis@yahoo.com wrote:
>
>>I am experiencing a problem where the brakes lock up after about four
>>to five miles of travel. I was told that the problem could be
>>resolved by replacing the master cylinder. I did, but the problem
>>continues. The only way to get going, is to release the pressure via
>>the bleeding valves. This works sometimes for an eighth of a mile or
>>sometimes up to ten miles. I removed all the relays from the ABS unit
>>with no luck.
>>
>>Is there someone who has experience this problem? How was it resolved?
>
> Brake vacuum servo is leaking................


Please, tell us more. I've never heard of this, and I'm not sure what
part(s) you are talking about, and how they play with the rest of the
system.
 >> Stay informed about: 1987 BMW 325E Brake Pressure Build Up 

Brake master cylinder would not cause this.

What are the EXACT symptoms you experienced? 'Brakes lock up' is a pretty
vague description.

Going by your current symptoms, it's nothing more that a seized caliper.



<cbwillia0605.DeleteThis@yahoo.com> wrote in message
news:1180018144.379160.200020@m36g2000hse.googlegroups.com...
>I am experiencing a problem where the brakes lock up after about four
> to five miles of travel. I was told that the problem could be
> resolved by replacing the master cylinder. I did, but the problem
> continues. The only way to get going, is to release the pressure via
> the bleeding valves. This works sometimes for an eighth of a mile or
> sometimes up to ten miles. I removed all the relays from the ABS unit
> with no luck.
>
> Is there someone who has experience this problem? How was it resolved?
>
 >> Stay informed about: 1987 BMW 325E Brake Pressure Build Up 

Pretty strange behavior allright. I see that the Bentley manual does list
this condition under trouble shooting and suggests that it may be caused by
the master cylinder although I don't personally understand how that would
happen. If it was a seized caliper it would probably only happen to one
wheel unless the car has been sitting unused for a long period of time. Do
all the wheels get hot or just one?? It seems like you have ruled out the
antiskid controller and the master cylinder so the only thing left is the
vacuum assist. You might try removing and plugging the vacuum line the next
time it happens to see if that fixes it. Just remember that you won't have
the power assist with the vacuum disconnected.
Good Luck and please let us know what the problem turns out to be.


<cbwillia0605 RemoveThis @yahoo.com> wrote in message
news:1180018144.379160.200020@m36g2000hse.googlegroups.com...
>I am experiencing a problem where the brakes lock up after about four
> to five miles of travel. I was told that the problem could be
> resolved by replacing the master cylinder. I did, but the problem
> continues. The only way to get going, is to release the pressure via
> the bleeding valves. This works sometimes for an eighth of a mile or
> sometimes up to ten miles. I removed all the relays from the ABS unit
> with no luck.
>
> Is there someone who has experience this problem? How was it resolved?
>
 >> Stay informed about: 1987 BMW 325E Brake Pressure Build Up 

Nedavno Haydon napisa:

> Brake master cylinder would not cause this.


I had a similar problem once with my Audi. All four wheels would lock
after about 20 minutes of travel. It seems that a problem was that my
"mechanic" filled up brake reservoir with wrong type of brake fluid,
that caused problem with rubber seals, and return spring was not able
to return cylinder back. I changed master cylinder and problem went
away.




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 >> Stay informed about: 1987 BMW 325E Brake Pressure Build Up 

In article <f36slh$1m1$1@news.monmouth.com>,
admin <admin.TakeThisOut@192.168.0.2> wrote:
> > Pretty strange behavior allright. I see that the Bentley manual does
> > list this condition under trouble shooting and suggests that it may
> > be caused by the master cylinder although I don't personally
> > understand how that would happen.

> The master cylinder has a relief port in it - that relieves brake
> pressure when you let up on the brake pedal. It basically opens the
> brake circuit(s) to the reservoir. This same port is also how the system
> is kept full as pads wear and the caliper pistons move out.

> If this port is plugged up, or the pedal isn't returning fully to the
> top position, it will cause the symptoms described.

I'm not convinced this could cause the brakes to lock on, though. Drag
slightly, yes. I'd be looking at a power assistance fault.

--
*He's not dead - he's electroencephalographically challenged

Dave Plowman dave.TakeThisOut@davenoise.co.uk London SW
To e-mail, change noise into sound.
 >> Stay informed about: 1987 BMW 325E Brake Pressure Build Up 

On May 24, 10:49 am, cbwillia0... DeleteThis @yahoo.com wrote:
> I am experiencing a problem where the brakes lockupafter about four
> to five miles of travel. I was told that the problem could be
> resolved by replacing the master cylinder. I did, but the problem
> continues. The only way to get going, is to release thepressurevia
> the bleeding valves. This works sometimes for an eighth of a mile or
> sometimesupto ten miles. I removed all the relays from the ABS unit
> with no luck.
>
> Is there someone who has experience this problem? How was it resolved?

5/25/2007 - Thanks for the many responses. I will try the suggestions
on Monday (Momorial Day)

To clarify - The symtom is like it has the hand brake connected to all
four wheels, and is applied to the maximum. All four wheels get very
hot if I try to push ahead before a complete stop. Whenever it is
totally locked, and I try to move, it just burns the clutch and the
car just squats.

I will post the results of the suggestions I have already received.
 >> Stay informed about: 1987 BMW 325E Brake Pressure Build Up 

This is commonly caused by a hose that is broken internally. The fluid
is allowed past but the "break" in the hose acts like a check valve
and doesn't allow the fluid to return and the caliper piston to
retract. This is not the case here as it would happen the first time
you applied the brakes. I also believe it is caused by a blockage in
the system. I've never seen a vacuum assist do this but I can't give a
definitive no on it either... As stated before, disconnect (and
plug/cap the vacuum line to the brake assist unit and see if the
problem goes away. Please let us know what fixes the problem.

On Fri, 25 May 2007 16:00:36 +0100, "Dave Plowman (News)"
<dave.RemoveThis@davenoise.co.uk> wrote:

>In article <f36slh$1m1$1@news.monmouth.com>,
> admin <admin.RemoveThis@192.168.0.2> wrote:
>> > Pretty strange behavior allright. I see that the Bentley manual does
>> > list this condition under trouble shooting and suggests that it may
>> > be caused by the master cylinder although I don't personally
>> > understand how that would happen.
>
>> The master cylinder has a relief port in it - that relieves brake
>> pressure when you let up on the brake pedal. It basically opens the
>> brake circuit(s) to the reservoir. This same port is also how the system
>> is kept full as pads wear and the caliper pistons move out.
>
>> If this port is plugged up, or the pedal isn't returning fully to the
>> top position, it will cause the symptoms described.
>
>I'm not convinced this could cause the brakes to lock on, though. Drag
>slightly, yes. I'd be looking at a power assistance fault.
 >> Stay informed about: 1987 BMW 325E Brake Pressure Build Up 

On Fri, 25 May 2007 16:00:36 +0100, "Dave Plowman (News)" <dave RemoveThis @davenoise.co.uk>
wrote:

>In article <f36slh$1m1$1@news.monmouth.com>,
> admin <admin RemoveThis @192.168.0.2> wrote:
>> > Pretty strange behavior allright. I see that the Bentley manual does
>> > list this condition under trouble shooting and suggests that it may
>> > be caused by the master cylinder although I don't personally
>> > understand how that would happen.
>
>> The master cylinder has a relief port in it - that relieves brake
>> pressure when you let up on the brake pedal. It basically opens the
>> brake circuit(s) to the reservoir. This same port is also how the system
>> is kept full as pads wear and the caliper pistons move out.
>
>> If this port is plugged up, or the pedal isn't returning fully to the
>> top position, it will cause the symptoms described.
>
>I'm not convinced this could cause the brakes to lock on, though. Drag
>slightly, yes. I'd be looking at a power assistance fault.


Thanks Dave..................
 >> Stay informed about: 1987 BMW 325E Brake Pressure Build Up 

Jeff Strickland wrote:
> <Oscar.RemoveThis@nowhere.com> wrote in message
>> Brake vacuum servo is leaking................
> Please, tell us more. I've never heard of this, and I'm not sure what
> part(s) you are talking about, and how they play with the rest of the
> system.

It sounds plausible. Pressing the brake pedal opens a valve to let
engine vacuum pull the brakes on harder, so a leak there could cause
such a problem.

That said, all cases of brakes locking on that I've seen have been
caused by a stiff linkage on cars that have the controls on the opposite
side to the master cylinder (ie RHD in a car originally designed for
LHD). But in that case the pedal would stay down.
 >> Stay informed about: 1987 BMW 325E Brake Pressure Build Up 

On May 25, 7:21 pm, cbwillia0....DeleteThis@yahoo.com wrote:
> On May 24, 10:49 am, cbwillia0....DeleteThis@yahoo.com wrote:
>
> > I am experiencing a problem where the brakes lockupafter about four
> > to five miles of travel. I was told that the problem could be
> > resolved by replacing the master cylinder. I did, but the problem
> > continues. The only way to get going, is to release thepressurevia
> > the bleeding valves. This works sometimes for an eighth of a mile or
> > sometimesupto ten miles. I removed all the relays from the ABS unit
> > with no luck.
>
> > Is there someone who has experience this problem? How was it resolved?
>
> 5/25/2007 - Thanks for the many responses. I will try the suggestions
> on Monday (Momorial Day)
>
> To clarify - The symtom is like it has the handbrakeconnected to all
> four wheels, and is applied to the maximum. All four wheels get very
> hot if I try to push ahead before a complete stop. Whenever it is
> totally locked, and I try to move, it just burns the clutch and the
> car just squats.
>
> I will post the results of the suggestions I have already received.

06/27/2007 - As I promised, even though it's been so long, I did
change the vacuum booster and that did fix my problem... Thank you
all.
 >> Stay informed about: 1987 BMW 325E Brake Pressure Build Up 

On Wed, 27 Jun 2007 19:14:01 -0700, cbwillia0605 DeleteThis @yahoo.com wrote:

>On May 25, 7:21 pm, cbwillia0... DeleteThis @yahoo.com wrote:
>> On May 24, 10:49 am, cbwillia0... DeleteThis @yahoo.com wrote:
>>
>> > I am experiencing a problem where the brakes lockupafter about four
>> > to five miles of travel. I was told that the problem could be
>> > resolved by replacing the master cylinder. I did, but the problem
>> > continues. The only way to get going, is to release thepressurevia
>> > the bleeding valves. This works sometimes for an eighth of a mile or
>> > sometimesupto ten miles. I removed all the relays from the ABS unit
>> > with no luck.
>>
>> > Is there someone who has experience this problem? How was it resolved?
>>
>> 5/25/2007 - Thanks for the many responses. I will try the suggestions
>> on Monday (Momorial Day)
>>
>> To clarify - The symtom is like it has the handbrakeconnected to all
>> four wheels, and is applied to the maximum. All four wheels get very
>> hot if I try to push ahead before a complete stop. Whenever it is
>> totally locked, and I try to move, it just burns the clutch and the
>> car just squats.
>>
>> I will post the results of the suggestions I have already received.
>
>06/27/2007 - As I promised, even though it's been so long, I did
>change the vacuum booster and that did fix my problem... Thank you
>all.

Well there you are. Glad to be of assistance and I believe that the Brake
Booster was a suggestion of mine following several similar instances of this
problem in the past.
 >> Stay informed about: 1987 BMW 325E Brake Pressure Build Up