strange brake problem

Can anyone suggest a cure for my UK Audi 80, I am at my wits end.
When pressing the brake pedal, the pedal was occasionally going nearly to
the floor, when pumped twice it would be OK and the brake pedal pressure
would be fine for days, I replaced the master cylinder with a new one from
Europarts UK and everything has been OK for a week, now the original problem
has happened again, brake pedal will go to the floor and pumped twice it
will have a good brake pedal and the brake pedal pressure
would be OK, brake pedal pressure is good and when braking car does not veer
from a straight line,
can anyone diagnose this problem as to why
brake pedal pressure keeps dropping from time to time? can't see any leaks,
master cyl reservoir fluid level is not dropping
Ps my audi 80 1.9TDI avant has got ABS discs brakes all round, 1994 model.
Thanks

"Nadia" > wrote in message
.uk...
> Can anyone suggest a cure for my UK Audi 80, I am at my wits end.
> When pressing the brake pedal, the pedal was occasionally going nearly to
> the floor, when pumped twice it would be OK and the brake pedal pressure
> would be fine for days, I replaced the master cylinder with a new one from
> Europarts UK and everything has been OK for a week, now the original
> problem
> has happened again, brake pedal will go to the floor and pumped twice it
> will have a good brake pedal and the brake pedal pressure
> would be OK, brake pedal pressure is good and when braking car does not
> veer from a straight line,
> can anyone diagnose this problem as to why
> brake pedal pressure keeps dropping from time to time? can't see any
> leaks,
> master cyl reservoir fluid level is not dropping
> Ps my audi 80 1.9TDI avant has got ABS discs brakes all round, 1994
> model.
> Thanks
>
>
The brake circuit is simple and there seems to be nothing wrong.
Keep in mind that also the clutch is getting it's fluid from the reservoir.
Maybe there is something wrong?

Just my 2 cents...

Ronald

Yes the clutch is fed from the reservoir too, nothing wrong with the clutch
operation, could this fault be caused by a sticking brake calliper?, the
brakes are ok when the brake pedal pressure is fine, does not pull from side
to side, just a thought? I will jack up the car and check each wheel, it's
annoying you want to know that you have good brakes all the time)


Nad


"R@L" > wrote in message
l...
>
> "Nadia" > wrote in message
> .uk...
>> Can anyone suggest a cure for my UK Audi 80, I am at my wits end.
>> When pressing the brake pedal, the pedal was occasionally going nearly to
>> the floor, when pumped twice it would be OK and the brake pedal pressure
>> would be fine for days, I replaced the master cylinder with a new one
>> from
>> Europarts UK and everything has been OK for a week, now the original
>> problem
>> has happened again, brake pedal will go to the floor and pumped twice it
>> will have a good brake pedal and the brake pedal pressure
>> would be OK, brake pedal pressure is good and when braking car does not
>> veer from a straight line,
>> can anyone diagnose this problem as to why
>> brake pedal pressure keeps dropping from time to time? can't see any
>> leaks,
>> master cyl reservoir fluid level is not dropping
>> Ps my audi 80 1.9TDI avant has got ABS discs brakes all round, 1994
>> model.
>> Thanks
>>
>>
> The brake circuit is simple and there seems to be nothing wrong.
> Keep in mind that also the clutch is getting it's fluid from the
> reservoir.
> Maybe there is something wrong?
>
> Just my 2 cents...
>
> Ronald
>

Nadia wrote:
> Can anyone suggest a cure for my UK Audi 80, I am at my wits end.
> When pressing the brake pedal, the pedal was occasionally going nearly to
> the floor, when pumped twice it would be OK and the brake pedal pressure
> would be fine for days, I replaced the master cylinder with a new one from
> Europarts UK and everything has been OK for a week, now the original problem
> has happened again, brake pedal will go to the floor and pumped twice it
> will have a good brake pedal and the brake pedal pressure
> would be OK, brake pedal pressure is good and when braking car does not veer
> from a straight line,
> can anyone diagnose this problem as to why
> brake pedal pressure keeps dropping from time to time? can't see any leaks,
> master cyl reservoir fluid level is not dropping
> Ps my audi 80 1.9TDI avant has got ABS discs brakes all round, 1994 model.
> Thanks
>
>
>
Your new M/C is likely junk. Especially if it was a "rebuilt" rather
than "new" piece.

"Nadia" > wrote in message
.uk...
> Yes the clutch is fed from the reservoir too, nothing wrong with the
> clutch operation, could this fault be caused by a sticking brake
> calliper?, the brakes are ok when the brake pedal pressure is fine, does
> not pull from side to side, just a thought? I will jack up the car and
> check each wheel, it's annoying you want to know that you have good brakes
> all the time)
>
>
> Nad

No, all brake calipers kind of stick. On disk brakes calipers are not
retracted.

My guess is -if not air in the system- also a lousy master cylinder.

Ronald

It was a new master cylinder not a refurbished one, I will contact the
supplier on monday.

Nad


"JimV" > wrote in message
...
> Nadia wrote:
>> Can anyone suggest a cure for my UK Audi 80, I am at my wits end.
>> When pressing the brake pedal, the pedal was occasionally going nearly to
>> the floor, when pumped twice it would be OK and the brake pedal pressure
>> would be fine for days, I replaced the master cylinder with a new one
>> from
>> Europarts UK and everything has been OK for a week, now the original
>> problem
>> has happened again, brake pedal will go to the floor and pumped twice it
>> will have a good brake pedal and the brake pedal pressure
>> would be OK, brake pedal pressure is good and when braking car does not
>> veer from a straight line,
>> can anyone diagnose this problem as to why
>> brake pedal pressure keeps dropping from time to time? can't see any
>> leaks,
>> master cyl reservoir fluid level is not dropping
>> Ps my audi 80 1.9TDI avant has got ABS discs brakes all round, 1994
>> model.
>> Thanks
>>
>>
>>
> Your new M/C is likely junk. Especially if it was a "rebuilt" rather than
> "new" piece.

What is your brake fluid level doing, are you loosing any, check at
the wheel (slave) cylinders as well.
Best of luck, John
1990 V8 Quattro
On Sun, 27 Feb 2005 17:46:52 GMT, "Nadia" >
wrote:

>Can anyone suggest a cure for my UK Audi 80, I am at my wits end.
>When pressing the brake pedal, the pedal was occasionally going nearly to
>the floor, when pumped twice it would be OK and the brake pedal pressure
>would be fine for days, I replaced the master cylinder with a new one from
>Europarts UK and everything has been OK for a week, now the original problem
>has happened again, brake pedal will go to the floor and pumped twice it
>will have a good brake pedal and the brake pedal pressure
>would be OK, brake pedal pressure is good and when braking car does not veer
>from a straight line,
> can anyone diagnose this problem as to why
>brake pedal pressure keeps dropping from time to time? can't see any leaks,
>master cyl reservoir fluid level is not dropping
>Ps my audi 80 1.9TDI avant has got ABS discs brakes all round, 1994 model.
>Thanks
>
>

Hi, brake level fluid never drops in reservoir, no leaks at any calliper
(pistons), today drove the car for 2 hours brake pedal firm, not spongy, car
brakes very well, after 2 hours, brake pedal goes to the floor little
pressure, pumped the brake pedal 2 twice got a firm brake pedal, then brake
pedal went to the floor again, pumped brake pedal twice got a firm brake
pedal again, brake pedal after driving another hour is firm and have good
brakes no sign of pressure dropping!!
Still looking for advice guys, I changed the master cylinder with a new one
when this symptom first happened, I guess the original problem was not the
master cylinder after all, I would have thought that problem is not a master
cylinder, since the problem still occurs.
checked so far..
No fluid leaks on ground.
Brake reservoir level does not drop.
car brakes in a straight line, tried this many times, perfect braking,
Handbrake (discs) holds car perfectly, and releases with no dragging, don't
think there is a seized piston (calliper)
What else is there to check,
brake pressure valve?
Servo? when the brake pedal pressure fell I stopped, switched off the engine
and pressed the pedal a couple of times and the pedal still went to the
floor
ABS???

Nad




<John> wrote in message ...
> What is your brake fluid level doing, are you loosing any, check at
> the wheel (slave) cylinders as well.
> Best of luck, John
> 1990 V8 Quattro
> On Sun, 27 Feb 2005 17:46:52 GMT, "Nadia" >
> wrote:
>
>>Can anyone suggest a cure for my UK Audi 80, I am at my wits end.
>>When pressing the brake pedal, the pedal was occasionally going nearly to
>>the floor, when pumped twice it would be OK and the brake pedal pressure
>>would be fine for days, I replaced the master cylinder with a new one from
>>Europarts UK and everything has been OK for a week, now the original
>>problem
>>has happened again, brake pedal will go to the floor and pumped twice it
>>will have a good brake pedal and the brake pedal pressure
>>would be OK, brake pedal pressure is good and when braking car does not
>>veer
>>from a straight line,
>> can anyone diagnose this problem as to why
>>brake pedal pressure keeps dropping from time to time? can't see any
>>leaks,
>>master cyl reservoir fluid level is not dropping
>>Ps my audi 80 1.9TDI avant has got ABS discs brakes all round, 1994
>>model.
>>Thanks
>>
>>
>

Suspect air in the system then.
Have you bled the system carefully, at master cylinder then each caliper in
turn? The order is Master Cyl / RH Rear / LH Rear / RH Front / LH Front.
When you are bleeding the rear cylinders you need to press the brake
regulator lever also. (you'll need an assistant!)

"Nadia" > wrote in message
.uk...
> Hi, brake level fluid never drops in reservoir, no leaks at any calliper
> (pistons), today drove the car for 2 hours brake pedal firm, not spongy,
> car brakes very well, after 2 hours, brake pedal goes to the floor little
> pressure, pumped the brake pedal 2 twice got a firm brake pedal, then
> brake pedal went to the floor again, pumped brake pedal twice got a firm
> brake pedal again, brake pedal after driving another hour is firm and have
> good brakes no sign of pressure dropping!!
> Still looking for advice guys, I changed the master cylinder with a new
> one when this symptom first happened, I guess the original problem was not
> the master cylinder after all, I would have thought that problem is not a
> master cylinder, since the problem still occurs.
> checked so far..
> No fluid leaks on ground.
> Brake reservoir level does not drop.
> car brakes in a straight line, tried this many times, perfect braking,
> Handbrake (discs) holds car perfectly, and releases with no dragging,
> don't think there is a seized piston (calliper)
> What else is there to check,
> brake pressure valve?
> Servo? when the brake pedal pressure fell I stopped, switched off the
> engine and pressed the pedal a couple of times and the pedal still went to
> the floor
> ABS???
>
> Nad
>
>
>
>
> <John> wrote in message ...
>> What is your brake fluid level doing, are you loosing any, check at
>> the wheel (slave) cylinders as well.
>> Best of luck, John
>> 1990 V8 Quattro
>> On Sun, 27 Feb 2005 17:46:52 GMT, "Nadia" >
>> wrote:
>>
>>>Can anyone suggest a cure for my UK Audi 80, I am at my wits end.
>>>When pressing the brake pedal, the pedal was occasionally going nearly to
>>>the floor, when pumped twice it would be OK and the brake pedal pressure
>>>would be fine for days, I replaced the master cylinder with a new one
>>>from
>>>Europarts UK and everything has been OK for a week, now the original
>>>problem
>>>has happened again, brake pedal will go to the floor and pumped twice it
>>>will have a good brake pedal and the brake pedal pressure
>>>would be OK, brake pedal pressure is good and when braking car does not
>>>veer
>>>from a straight line,
>>> can anyone diagnose this problem as to why
>>>brake pedal pressure keeps dropping from time to time? can't see any
>>>leaks,
>>>master cyl reservoir fluid level is not dropping
>>>Ps my audi 80 1.9TDI avant has got ABS discs brakes all round, 1994
>>>model.
>>>Thanks
>>>
>>>
>>
>
>

Could also be water in the (old?) brake fluid.
If cold no problem, after heating up it becomes steam which can be
pressed together ---> strange breaking behaviour.
(I hope you understand what I mean, english is not my native tongue)

"Fred" > wrote in :

> Suspect air in the system then.
> Have you bled the system carefully, at master cylinder then each
> caliper in turn? The order is Master Cyl / RH Rear / LH Rear / RH
> Front / LH Front. When you are bleeding the rear cylinders you need to
> press the brake regulator lever also. (you'll need an assistant!)
>
> "Nadia" > wrote in message
> .uk...
>> Hi, brake level fluid never drops in reservoir, no leaks at any
>> calliper (pistons), today drove the car for 2 hours brake pedal firm,
>> not spongy, car brakes very well, after 2 hours, brake pedal goes to
>> the floor little pressure, pumped the brake pedal 2 twice got a firm
>> brake pedal, then brake pedal went to the floor again, pumped brake
>> pedal twice got a firm brake pedal again, brake pedal after driving
>> another hour is firm and have good brakes no sign of pressure
>> dropping!! Still looking for advice guys, I changed the master
>> cylinder with a new one when this symptom first happened, I guess the
>> original problem was not the master cylinder after all, I would have
>> thought that problem is not a master cylinder, since the problem
>> still occurs. checked so far..
>> No fluid leaks on ground.
>> Brake reservoir level does not drop.
>> car brakes in a straight line, tried this many times, perfect
>> braking, Handbrake (discs) holds car perfectly, and releases with no
>> dragging, don't think there is a seized piston (calliper)
>> What else is there to check,
>> brake pressure valve?
>> Servo? when the brake pedal pressure fell I stopped, switched off the
>> engine and pressed the pedal a couple of times and the pedal still
>> went to the floor
>> ABS???
>>
>> Nad
>>
>>
>>
>>
>> <John> wrote in message
>> ...
>>> What is your brake fluid level doing, are you loosing any, check at
>>> the wheel (slave) cylinders as well.
>>> Best of luck, John
>>> 1990 V8 Quattro
>>> On Sun, 27 Feb 2005 17:46:52 GMT, "Nadia" >
>>> wrote:
>>>
>>>>Can anyone suggest a cure for my UK Audi 80, I am at my wits end.
>>>>When pressing the brake pedal, the pedal was occasionally going
>>>>nearly to the floor, when pumped twice it would be OK and the brake
>>>>pedal pressure would be fine for days, I replaced the master
>>>>cylinder with a new one from
>>>>Europarts UK and everything has been OK for a week, now the original
>>>>problem
>>>>has happened again, brake pedal will go to the floor and pumped
>>>>twice it will have a good brake pedal and the brake pedal pressure
>>>>would be OK, brake pedal pressure is good and when braking car does
>>>>not veer
>>>>from a straight line,
>>>> can anyone diagnose this problem as to why
>>>>brake pedal pressure keeps dropping from time to time? can't see any
>>>>leaks,
>>>>master cyl reservoir fluid level is not dropping
>>>>Ps my audi 80 1.9TDI avant has got ABS discs brakes all round, 1994
>>>>model.
>>>>Thanks
>>>>
>>>>
>>>
>>
>>
>
>