Sinking Defender break pedal... No fluid loss!?!

Jon · May 17, 2006

Hi all,
Another problem has reared its head with my new (to me) TD5 90. For
those that dont know its a 2000 model with 33,000 miles.

Since off-roading at Driffield this weekend I now have very crap
brakes and my pedal sinks with constant pressure.

I have had each wheel off and all the calipers and discs are dry &
clean. Flexible hoses arent leaking either and its not loosing fluid.
Pads are about 15% - 25% worn.

Any ideas?

If I pump the break pedal I can restore normal feeling, then after a
second or so I can feel the pedal moving downwards slowly, but it
doesnt seem to want to drop to the floor.

Any ideas? Could I have a leak in the diaphram / servo somewhere?

Thanks
Jon

Lee_D · May 17, 2006

Jon <[email protected]> uttered summat worrerz funny about:
> Any ideas? Could I have a leak in the diaphram / servo somewhere?
>
>
> Thanks
> Jon

Check the servo hoses. I had a pipe chaff through on my last RRC which
displayed similar symptoms. Worse when the pipe was warm as it leaked
more... it only got warm on a motorway run which provided some interesting
entertaiment and brown pant moments when coming off at a junction.

Lee

rads · May 17, 2006

On Wed, 17 May 2006 13:25:52 +0100, "Lee_D"
<[email protected]> wrote:

>Jon <[email protected]> uttered summat worrerz funny about:
>> Any ideas? Could I have a leak in the diaphram / servo somewhere?
>>
>>
>> Thanks
>> Jon
>
>Check the servo hoses. I had a pipe chaff through on my last RRC which
>displayed similar symptoms. Worse when the pipe was warm as it leaked
>more... it only got warm on a motorway run which provided some interesting
>entertaiment and brown pant moments when coming off at a junction.
>
>Lee
Or master cylinder seals, possibly?

David

beamendsltd · May 17, 2006

In message <[email protected]>
rads <[email protected]> wrote:

> On Wed, 17 May 2006 13:25:52 +0100, "Lee_D"
> <[email protected]> wrote:
>
> >Jon <[email protected]> uttered summat worrerz funny about:
> >> Any ideas? Could I have a leak in the diaphram / servo somewhere?
> >>
> >>
> >> Thanks
> >> Jon
> >
> >Check the servo hoses. I had a pipe chaff through on my last RRC which
> >displayed similar symptoms. Worse when the pipe was warm as it leaked
> >more... it only got warm on a motorway run which provided some interesting
> >entertaiment and brown pant moments when coming off at a junction.
> >
> >Lee
> Or master cylinder seals, possibly?
>
> David

Master cylinder seals, possibly slave cylinder sucking air in -
vacuum loss usually makes the pedal go rock hard.

Richard
--
www.beamends-lrspares.co.uk [email protected]
RISC-OS - Where have all the good guys gone?
Boycott the Yorkshire Dales - No Play, No Pay

Jon · May 17, 2006

Thanks for the reply's all. Looks like I'll check the hoses and then
get to grips with the master cylinder...

Looks like another joyous weekend! Still, it keeps me out of the
garden!

Jon

>Hi all,
>Another problem has reared its head with my new (to me) TD5 90. For
>those that dont know its a 2000 model with 33,000 miles.
>
>Since off-roading at Driffield this weekend I now have very crap
>brakes and my pedal sinks with constant pressure.
>
>I have had each wheel off and all the calipers and discs are dry &
>clean. Flexible hoses arent leaking either and its not loosing fluid.
>Pads are about 15% - 25% worn.
>
>Any ideas?
>
>If I pump the break pedal I can restore normal feeling, then after a
>second or so I can feel the pedal moving downwards slowly, but it
>doesnt seem to want to drop to the floor.
>
>Any ideas? Could I have a leak in the diaphram / servo somewhere?
>
>
>Thanks
>Jon

Landylover · May 17, 2006

My money is on either the master or slave. Fluid is bypassing the
seals on one or the other - hence no loss. Classic symptoms.

Derek · May 17, 2006

"Landylover" <[email protected]> wrote in message
news:[email protected]...
> My money is on either the master or slave. Fluid is bypassing the
> seals on one or the other - hence no loss. Classic symptoms.

master cylinder seal leak sounds about right to me if its the slave it would
be dripping past the pistons.One other alternative to consider if you have
had a VERY enthusiastic day hot brake fluid can leave air in the system
resulting in a spongy pedal which compresses depends how old the fluid in
the system is and whether is has been bled properly at service.
Derek

icky · May 17, 2006

"Jon" <[email protected]> wrote in message
news:[email protected]...
> Thanks for the reply's all. Looks like I'll check the hoses and then
> get to grips with the master cylinder...
>
> Looks like another joyous weekend! Still, it keeps me out of the
> garden!
>
>
> Jon
>
>
>>Hi all,
>>Another problem has reared its head with my new (to me) TD5 90. For
>>those that dont know its a 2000 model with 33,000 miles.
>>
>>Since off-roading at Driffield this weekend I now have very crap
>>brakes and my pedal sinks with constant pressure.
>>
>>I have had each wheel off and all the calipers and discs are dry &
>>clean. Flexible hoses arent leaking either and its not loosing fluid.
>>Pads are about 15% - 25% worn.
>>
>>Any ideas?
>>
>>If I pump the break pedal I can restore normal feeling, then after a
>>second or so I can feel the pedal moving downwards slowly, but it
>>doesnt seem to want to drop to the floor.
>>
>>Any ideas? Could I have a leak in the diaphram / servo somewhere?
>>
>>
>>Thanks
>>Jon

Hi Jon
I agree with Richard, every servo leek I have come across makes the pedal go
hard. Try clamping the flexi hoses with vice grips ( or flexi clamps if your
posh ) if the pedal still drops suspect the master cylinder, if it is firm
release one flexi at a time and try the pedal to indicate where the problem
may be.

Hope this helps

Icky

Jon · May 19, 2006

On Wed, 17 May 2006 20:01:21 GMT, "Derek"
<[email protected]> wrote:

>
>"Landylover" <[email protected]> wrote in message
>news:[email protected]...
>> My money is on either the master or slave. Fluid is bypassing the
>> seals on one or the other - hence no loss. Classic symptoms.
>
>master cylinder seal leak sounds about right to me if its the slave it would
>be dripping past the pistons.One other alternative to consider if you have
>had a VERY enthusiastic day hot brake fluid can leave air in the system
>resulting in a spongy pedal which compresses depends how old the fluid in
>the system is and whether is has been bled properly at service.
>Derek
>

Brake fluid is newish - was replaced about 3000 miles ago.

Brakes were fine so it only just started.

Day wasnt that enthusiastic and the fluid certainly wont have boiled
to induce air.

Will check the master cylinder tomorrow...

Jon · May 23, 2006

On Wed, 17 May 2006 13:21:04 +0100, Jon <[email protected]> wrote:

>Hi all,
>Another problem has reared its head with my new (to me) TD5 90. For
>those that dont know its a 2000 model with 33,000 miles.
>
>Since off-roading at Driffield this weekend I now have very crap
>brakes and my pedal sinks with constant pressure.
>
>I have had each wheel off and all the calipers and discs are dry &
>clean. Flexible hoses arent leaking either and its not loosing fluid.
>Pads are about 15% - 25% worn.
>
>Any ideas?
>
>If I pump the break pedal I can restore normal feeling, then after a
>second or so I can feel the pedal moving downwards slowly, but it
>doesnt seem to want to drop to the floor.
>
>Any ideas? Could I have a leak in the diaphram / servo somewhere?
>
>
>Thanks
>Jon

Finally got around to looking at the brakes in a bit more detail last
night, but only for a few minutes.

There is still not loss of fluid in the resevoir or signs of leakage
around any caliper or flexible pipe.

BUT... I did note that the fluid in the two halves of the resevoir are
clearly different colours!

The compartment furthest away from the servo looks like brand new DOT4
and is a vegitable oil / yellow colour. The resevour compartment
nearest the servo however is a much darker colour. Could this be
stained with rubber if some internal seals have given way??

The brakes have not deteriorated any more but I have found out that I
need a runway to stop from 70 - 80 mph! The feeling is just like when
fluid boils...the more you press, the more aware you are nothing is
happening!!! I can however say that the fluid has not boiled.

Jon

AJH · May 23, 2006

On Tue, 23 May 2006 08:13:51 +0100, Jon <[email protected]> wrote:

>The compartment furthest away from the servo looks like brand new DOT4
>and is a vegitable oil / yellow colour. The resevour compartment
>nearest the servo however is a much darker colour. Could this be
>stained with rubber if some internal seals have given way??

More likely that the system contains two different oils, it is
possible that the oil could have carbonised. I have had this happen on
a tractor with internal wet brakes but I didn't think dry brakes could
transfer enough temperature through a caliper.

The symptoms are typical mastewr cyclinder seal leak, as has been
pointed out in earlier responses, what happens is the seal leaks a bit
around the side under mild pressure but when you stamp on it the extra
pressure "balloons" the seal against the wall to reseal it.

AJH

Austin Shackles · May 23, 2006

On or around Tue, 23 May 2006 08:13:51 +0100, Jon <[email protected]>
enlightened us thusly:

>>
>>Any ideas?
>>
>>If I pump the break pedal I can restore normal feeling, then after a
>>second or so I can feel the pedal moving downwards slowly, but it
>>doesnt seem to want to drop to the floor.
>>
>>Any ideas? Could I have a leak in the diaphram / servo somewhere?
>
>Finally got around to looking at the brakes in a bit more detail last
>night, but only for a few minutes.
>
>There is still not loss of fluid in the resevoir or signs of leakage
>around any caliper or flexible pipe.
>
>BUT... I did note that the fluid in the two halves of the resevoir are
>clearly different colours!
>

you've got dual circuit brakes, sounds like one circuit malfunctioning.

and BTW, what you describe is brake fade... fluid boiling results in the
pedal going to the floor and doing sod-all, due to vapour not being
compressible in the same way as fluid.
--
Austin Shackles. www.ddol-las.net my opinions are just that
"Festina Lente" (Hasten slowly) Suetonius (c.70-c.140) Augustus, 25

Jon · May 26, 2006

On Tue, 23 May 2006 09:21:51 +0100, AJH <[email protected]> wrote:

>On Tue, 23 May 2006 08:13:51 +0100, Jon <[email protected]> wrote:
>
>>The compartment furthest away from the servo looks like brand new DOT4
>>and is a vegitable oil / yellow colour. The resevour compartment
>>nearest the servo however is a much darker colour. Could this be
>>stained with rubber if some internal seals have given way??
>
>More likely that the system contains two different oils, it is
>possible that the oil could have carbonised. I have had this happen on
>a tractor with internal wet brakes but I didn't think dry brakes could
>transfer enough temperature through a caliper.
>
>The symptoms are typical mastewr cyclinder seal leak, as has been
>pointed out in earlier responses, what happens is the seal leaks a bit
>around the side under mild pressure but when you stamp on it the extra
>pressure "balloons" the seal against the wall to reseal it.
>
>AJH

Well I managed to get a new Lucas master cylinder... Low and behold
the local LR garage was the same price as my only other quote (sorry
Richard) and most convenient.

Problem is that now Ive got the new master cylinder on and brakes
thoroughly bled with new DOT4 I STILL have the same problem.

Flexible hoses wouldnt baloon enough under pressure to induce a
sinking pedel would they?

Need to do a bit more driving to test out but it really has me baffled
now!

Are the TD5's known for air locking when bleeding? I got quite a bit
of air out and flushed a lot of fluid through after the last air at
each wheel so Im sure under normal circumstances there shouldnt be any
air in the system.

If the vacuum motor thing had packed up that wouldnt give me my
symptoms would it?

Hopefully someone can shine a light on whats fast becoming a pain in
the ar5e car!

Jon
....should have stuck with the TDi

Richard Brookman · May 26, 2006

Jon wrote:

|| Well I managed to get a new Lucas master cylinder... Low and behold
|| the local LR garage was the same price as my only other quote (sorry
|| Richard) and most convenient.
||
|| Problem is that now Ive got the new master cylinder on and brakes
|| thoroughly bled with new DOT4 I STILL have the same problem.
||
|| Flexible hoses wouldnt baloon enough under pressure to induce a
|| sinking pedel would they?

If the pedal is just spongey, it's air still in the system. If the pedal
actually sinks to the floor, you've got a leak somewhere, with fluid
bypassing the pistons. One good diagnostic is to get a hose clamp and clamp
off the rear flexi on the back axle. If the problem is still there, you
know the problem's at the front. Clamp off the front hoses in turn. If
there's still a problem after that, then it must be the master cylinder.
Not recommended if you've got braided hoses, though.

--
Rich
==============================

I don't approve of signatures, so I don't have one.

Jon · May 27, 2006

On Fri, 26 May 2006 21:47:24 +0100, "Richard Brookman"
<[email protected]> wrote:

>Jon wrote:
>
>|| Well I managed to get a new Lucas master cylinder... Low and behold
>|| the local LR garage was the same price as my only other quote (sorry
>|| Richard) and most convenient.
>||
>|| Problem is that now Ive got the new master cylinder on and brakes
>|| thoroughly bled with new DOT4 I STILL have the same problem.
>||
>|| Flexible hoses wouldnt baloon enough under pressure to induce a
>|| sinking pedel would they?
>
>If the pedal is just spongey, it's air still in the system. If the pedal
>actually sinks to the floor, you've got a leak somewhere, with fluid
>bypassing the pistons. One good diagnostic is to get a hose clamp and clamp
>off the rear flexi on the back axle. If the problem is still there, you
>know the problem's at the front. Clamp off the front hoses in turn. If
>there's still a problem after that, then it must be the master cylinder.
>Not recommended if you've got braided hoses, though.

Thanks Rich,
Time to get out some clamps!

Jon

Derek · May 28, 2006

"Jon" <[email protected]> wrote in message
news:[email protected]...
> On Tue, 23 May 2006 09:21:51 +0100, AJH <[email protected]> wrote:
>
>>On Tue, 23 May 2006 08:13:51 +0100, Jon <[email protected]> wrote:
>>
>>>The compartment furthest away from the servo looks like brand new DOT4
>>>and is a vegitable oil / yellow colour. The resevour compartment
>>>nearest the servo however is a much darker colour. Could this be
>>>stained with rubber if some internal seals have given way??
>>
>>More likely that the system contains two different oils, it is
>>possible that the oil could have carbonised. I have had this happen on
>>a tractor with internal wet brakes but I didn't think dry brakes could
>>transfer enough temperature through a caliper.
>>
>>The symptoms are typical mastewr cyclinder seal leak, as has been
>>pointed out in earlier responses, what happens is the seal leaks a bit
>>around the side under mild pressure but when you stamp on it the extra
>>pressure "balloons" the seal against the wall to reseal it.
>>
>>AJH
>
>
> Well I managed to get a new Lucas master cylinder... Low and behold
> the local LR garage was the same price as my only other quote (sorry
> Richard) and most convenient.
>
> Problem is that now Ive got the new master cylinder on and brakes
> thoroughly bled with new DOT4 I STILL have the same problem.
>
> Flexible hoses wouldnt baloon enough under pressure to induce a
> sinking pedel would they?
>
> Need to do a bit more driving to test out but it really has me baffled
> now!
>
> Are the TD5's known for air locking when bleeding? I got quite a bit
> of air out and flushed a lot of fluid through after the last air at
> each wheel so Im sure under normal circumstances there shouldnt be any
> air in the system.
>
> If the vacuum motor thing had packed up that wouldnt give me my
> symptoms would it?
>
> Hopefully someone can shine a light on whats fast becoming a pain in
> the ar5e car!
>
>
> Jon
> ...should have stuck with the TDi

I have only had a flexible balloon once ( On a Morris1000 ) that
turned out to be fluid running between the layers once you are looking
for it the problem is visable as the pipe flexes unlikely but go with
Richards suggestion clamp the pipes off to eliminate where its happening.
Derek
right its not raining I have the ep90 its front diff time.................

Sinking Defender break pedal... No fluid loss!?!

Jon

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