I have a 1994 Astra 1.4i. It needed a new flex hose leading to the o/s
rear brake to get the MOT. When I picked it up and drove it home I
notice that with light pressure on the brake pedal occasionally it
would sink down a few inches with little resistance. I took it back to
the garage and he took off all the wheels and bled each wheel brake
while I was there but when driving home again the pedal was still
sinking down. He had given it a road test but he said it didn't do it
for him. I think he was braking harder than I was. The servo check
seemed ok. Can anyone tell me what the next step is.

"gJF"  wrote in message 
news:1124442387.381863.44620@g47g2000cwa.googlegroups.com...

>I have a 1994 Astra 1.4i. It needed a new flex hose leading to the o/s
> rear brake to get the MOT. When I picked it up and drove it home I
> notice that with light pressure on the brake pedal occasionally it
> would sink down a few inches with little resistance. I took it back to
> the garage and he took off all the wheels and bled each wheel brake
> while I was there but when driving home again the pedal was still
> sinking down. He had given it a road test but he said it didn't do it
> for him. I think he was braking harder than I was. The servo check
> seemed ok. Can anyone tell me what the next step is.



If there is a problem and there are no evident leaks and they have been bled 
properly.  My next port of call would be the master cylinder.  If you don't 
know what to check for when bleeding brakes etc, then take it to another - 
or -more - garages and get opinions.  It is *very* difficult to find a 
garage with mechanics that you can trust.

"gJF"  wrote in message
news:1124442387.381863.44620@g47g2000cwa.googlegroups.com...

> I have a 1994 Astra 1.4i. It needed a new flex hose leading to the o/s
> rear brake to get the MOT. When I picked it up and drove it home I
> notice that with light pressure on the brake pedal occasionally it
> would sink down a few inches with little resistance. I took it back to
> the garage and he took off all the wheels and bled each wheel brake
> while I was there but when driving home again the pedal was still
> sinking down. He had given it a road test but he said it didn't do it
> for him. I think he was braking harder than I was. The servo check
> seemed ok. Can anyone tell me what the next step is.


Could be seal/s failing in the master cylinder.
It's not unknown for a seal to leak under light pressure, but seal under
heavy pressure.
Mike.

In article ,
   gJF  wrote:

> I have a 1994 Astra 1.4i. It needed a new flex hose leading to the o/s
> rear brake to get the MOT. When I picked it up and drove it home I
> notice that with light pressure on the brake pedal occasionally it
> would sink down a few inches with little resistance. I took it back to
> the garage and he took off all the wheels and bled each wheel brake
> while I was there but when driving home again the pedal was still
> sinking down. He had given it a road test but he said it didn't do it
> for him. I think he was braking harder than I was. The servo check
> seemed ok. Can anyone tell me what the next step is.


Has the vehicle had regular brake fluid changes throughout its life?

If not, this might be the first time the master cylinder has been
depressed fully (to bleed the brakes) and crud in the master cylinder has
damaged the seals.

It's quite possible for those to leak with no external signs or loss of
fluid.

-- 
*What happens if you get scared half to death twice? *

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

Dave Plowman (News) wrote:

> In article ,
>    gJF  wrote:
> > I have a 1994 Astra 1.4i. It needed a new flex hose leading to the o/s
> > rear brake to get the MOT. When I picked it up and drove it home I
> > notice that with light pressure on the brake pedal occasionally it
> > would sink down a few inches with little resistance. I took it back to
> > the garage and he took off all the wheels and bled each wheel brake
> > while I was there but when driving home again the pedal was still
> > sinking down. He had given it a road test but he said it didn't do it
> > for him. I think he was braking harder than I was. The servo check
> > seemed ok. Can anyone tell me what the next step is.
>
> Has the vehicle had regular brake fluid changes throughout its life?
>
> If not, this might be the first time the master cylinder has been
> depressed fully (to bleed the brakes) and crud in the master cylinder has
> damaged the seals.
>

> It's quite possible for those to leak with no external signs or loss of
> fluid.
>
> --
> *What happens if you get scared half to death twice? *
>
>     Dave Plowman        dave@davenoise.co.uk           London SW
>



I don't know about the fluid changes.  The mechanic said that he had
bled it by gravity as he did when I took it back.  It looks like a new
master cylinder.  Thanks for the advice.




                  To e-mail, change noise into sound.

"gJF"  wrote in message 
news:1124457266.089182.175230@g44g2000cwa.googlegroups.com...

>
> Dave Plowman (News) wrote:
>> In article ,
>>    gJF  wrote:
>> > I have a 1994 Astra 1.4i. It needed a new flex hose leading to the o/s
>> > rear brake to get the MOT. When I picked it up and drove it home I
>> > notice that with light pressure on the brake pedal occasionally it
>> > would sink down a few inches with little resistance. I took it back to
>> > the garage and he took off all the wheels and bled each wheel brake
>> > while I was there but when driving home again the pedal was still
>> > sinking down. He had given it a road test but he said it didn't do it
>> > for him. I think he was braking harder than I was. The servo check
>> > seemed ok. Can anyone tell me what the next step is.
>>
>> Has the vehicle had regular brake fluid changes throughout its life?
>>
>> If not, this might be the first time the master cylinder has been
>> depressed fully (to bleed the brakes) and crud in the master cylinder has
>> damaged the seals.
>>
>
>> It's quite possible for those to leak with no external signs or loss of
>> fluid.
>>
>> --
>> *What happens if you get scared half to death twice? *
>>
>>     Dave Plowman        dave@davenoise.co.uk           London SW
>>
>
>
> I don't know about the fluid changes.  The mechanic said that he had
> bled it by gravity as he did when I took it back.  It looks like a new
> master cylinder.  Thanks for the advice.




Gravity bleeding will release some of the air but not all of it.  If this is 
all the mechanic has done I would take it somewhere else to get it bled 
properly.