The Natural Philosopher wrote:
On 18/05/16 17:45, Tim Lamb wrote:
In message , The Natural Philosopher
writes
On 18/05/16 12:39, Tim Lamb wrote:
OK so it is overdue for an MOT. Probably done 1000 miles in the
year, barn stored.

Couple of advisories on last years.... brake pipes slightly
corroded near flex hose joint and inner side walls slightly
deteriorated on rear tyres.

Not much I can do about the tyres but wire brush off any brake
pipe rust and coat with..?

No, get the bloody things replaced. I've had brake failure..

Regular event on early Minis. Usually snatchy brakes from corroded
cylinders though.

I think a limited mileage, stored under cover slightly corroded pipe
is not going fail totally in 12 months.

The point is there is no 'partial failure' mode with brakes. Either
the pipes hold up to the pressure, or you have either no brakes, or,
if its a dual master cylinder, one diagonal pair of brakes only.

And all there is left is a hand brake and the engine braking.
Ive been lucky. Ive had front suspension fail, and brakes fail and
both were at low speed.

Ive also had a bonnet blow up in my face at 70mph in the fast lane of
the A1. Not so nice.

Mk 2 Cortina?

I am as parsimonious on unnecessary repairs as the next man, but
brakes I don't mess with. Typically even at garage rates, they are not
expensive to fix.


I'll be fitting two new discs and pads on the Hippo* in a few months,
not because it wouldn't pass a test, but because I've noticed the
braking isn't quite all there when I need it.



I'll report what they have to say.



*https://www.landyzone.co.uk/attachments/12-jpg.3353/

On 18/05/2016 13:43, michael adams wrote:
"Tim wrote in message
...
OK so it is overdue for an MOT. Probably done 1000 miles in the year, barn stored.

Couple of advisories on last years.... brake pipes slightly corroded near flex hose
joint and inner side walls slightly deteriorated on rear tyres.

Not much I can do about the tyres but wire brush off any brake pipe rust and coat
with..?
--
Tim Lamb

The first thing any Test Centre will do is check any advisories
from last year either on paper of if necessary online,



Not so. My wife's 2000MY Puma only does about 2k miles per annum. The
MOT (always done by the same garage) throws up a variety of advisories
such as slightly corroded brake pipes or slightly worn suspension
bushes. We do nothing about it between times and, as often a not, an
advisory which appears one year isn't repeated the next despite no
remedial work having been done. Seems to depend more on the whim of the
tester than anything else.
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

On 18/05/2016 19:45, Roger Mills wrote:
On 18/05/2016 12:39, Tim Lamb wrote:
OK so it is overdue for an MOT. Probably done 1000 miles in the year,
barn stored.

Couple of advisories on last years.... brake pipes slightly corroded
near flex hose joint and inner side walls slightly deteriorated on rear
tyres.

Not much I can do about the tyres but wire brush off any brake pipe rust
and coat with..?

You need to satisfy yourself that it's just surface rust, and that the
corrosion hasn't weakened the pipe. Then wire brush it and wipe it with
an oily rag.

I think 'pitted' used to mean a fail or at least a pipe on the way out,
and slight corrosion not much more than normal, and one to watch.

I'd suggest posting on uk.rec.car.maintenance for some more insights.

--
Cheers, Rob

On 18/05/2016 19:47, polygonum wrote:
On 18/05/2016 19:33, Adrian wrote:
Neglecting changing DOT fluid is the single biggest reason for replacing
brake and clutch cylinders and calipers, not to mention the risk of the
fluid boiling.

Why does not changing the fluid make it more likely to boil? I'd
understand if you said that any water in the fluid could turn to
steam... Or if I were convinced that any water content would cause
depression of boiling point...

Not in the least arguing against changing the fluid.

DOT fluid is hygroscopic, ie absorbs water. The longer you leave it, the
more water there is in it. Changing it means you get back to fluid with
no water in it.

And yes, water in it will cause problems other than corrosion - get it
hot and you do inded lose your brakes as things boil.

On Wed, 18 May 2016 20:07:04 +0100, RJH wrote:

You need to satisfy yourself that it's just surface rust, and that the
corrosion hasn't weakened the pipe. Then wire brush it and wipe it with
an oily rag.

I think 'pitted' used to mean a fail or at least a pipe on the way out,
and slight corrosion not much more than normal, and one to watch.

Fail is having lost 1/3 of the original thickness or more.

On Wed, 18 May 2016 20:36:04 +0100, Clive George wrote:

Neglecting changing DOT fluid is the single biggest reason for
replacing brake and clutch cylinders and calipers, not to mention the
risk of the fluid boiling.

Why does not changing the fluid make it more likely to boil? I'd
understand if you said that any water in the fluid could turn to
steam... Or if I were convinced that any water content would cause
depression of boiling point...

Not in the least arguing against changing the fluid.

DOT fluid is hygroscopic, ie absorbs water. The longer you leave it, the
more water there is in it. Changing it means you get back to fluid with
no water in it.

....and the boiling point of the water in the fluid is much lower than the
boiling point of the fluid. Heat the fluid to 100degC or more, and the
water in the fluid boils, turning to steam. And steam is compressible.

The old DOT3 boils at 205degC. DOT4, the most common stuff today, boils
at 230degC. DOT5.1 boils at 260degC, as does the silicone DOT5, which
isn't miscible with the other three.

On 18/05/2016 20:45, Adrian wrote:
On Wed, 18 May 2016 20:36:04 +0100, Clive George wrote:

Neglecting changing DOT fluid is the single biggest reason for
replacing brake and clutch cylinders and calipers, not to mention the
risk of the fluid boiling.

Why does not changing the fluid make it more likely to boil? I'd
understand if you said that any water in the fluid could turn to
steam... Or if I were convinced that any water content would cause
depression of boiling point...

Not in the least arguing against changing the fluid.

DOT fluid is hygroscopic, ie absorbs water. The longer you leave it, the
more water there is in it. Changing it means you get back to fluid with
no water in it.

....and the boiling point of the water in the fluid is much lower than the
boiling point of the fluid. Heat the fluid to 100degC or more, and the
water in the fluid boils, turning to steam. And steam is compressible.

The old DOT3 boils at 205degC. DOT4, the most common stuff today, boils
at 230degC. DOT5.1 boils at 260degC, as does the silicone DOT5, which
isn't miscible with the other three.

I am delighted to read about absorbing water, creation of steam,
changing the fluid so it is dry, and the actual boiling points. All
relevant and some mentioned in my question/response. But none of them
seem to support the claim I was questioning: that not changing the brake
fluid makes the brake fluid itself more likely to boil.

--
Rod

On 18/05/2016 12:39, Tim Lamb wrote:
OK so it is overdue for an MOT. Probably done 1000 miles in the year,
barn stored.

Couple of advisories on last years.... brake pipes slightly corroded
near flex hose joint and inner side walls slightly deteriorated on rear
tyres.

Not much I can do about the tyres but wire brush off any brake pipe rust
and coat with..?

Just go for the MOT, it wont fail unless its dangerous.
You don't want to drive a dangerous car or are you planning on passing
it off on some mug?

On Wed, 18 May 2016 16:29:00 +0100, "Dave Plowman (News)"
wrote:

In article ,
wrote:
Not all advisories necessarily indicate work that will need doing
before the next year's MOT. For example my bike MOT sometimes gets:-
"Steering headbearing has slight free play (2.2.2)". As the tester
always says that's really down to how tight one prefers to have it.

I get an advisory most years about slight play in the front wheel bearings
on my SD1. Of course there is slight play. They are adjustable, and that's
how they are set. If you set them with no play, they overheat and spew out
the grease...

Or the advisory that the front brake pads are quite worn ... when the
car may only do 100 miles between MOT's. But I'm guessing they can't
know or should assume that so they would mention it because they
looked lower than most brake pads should get for a driver doing
'typical' miles / year.

And all the advisories that mysteriously vanish between tests without
anything being done about them. ;-)

Or the pass that's issued for something to fail on the way back from
the MOT station (I had a brake pipe fail on my Morris Minor because it
sat inside the chassis and couldn't be inspected).

Cheers, T i m

Adrian wrote:

It really doesn't make any difference whether there's an advisory from
the previous year or not. He should be checking the brake pipes...

And, as I said, he doesn't KNOW if there was an advisory or not the
previous year.

Previous advisories now come up on the computer, don't they?

jim a écrit :
Tim Lamb Wrote in message:
OK so it is overdue for an MOT. Probably done 1000 miles in the year,
barn stored.

Couple of advisories on last years.... brake pipes slightly corroded
near flex hose joint and inner side walls slightly deteriorated on rear
tyres.

Not much I can do about the tyres but wire brush off any brake pipe rust
and coat with..?

Grease?

I agree, the thickest most waterproof grease you can lay your hands on.

Check it is ONLY surface rust, clean it off, paint it with oil, then
grease. This is as advised by my MOT inspector and it said it is no
reason for an inspector to be suspcious - they can feel the condition
easily through the grease.

Underseal will only seal in the moisure and rust - the rusting will
continue under the underseal, besides it is a reason for the MOT guy to
be suspcious.

In message , Clive
George writes
On 18/05/2016 19:47, polygonum wrote:
On 18/05/2016 19:33, Adrian wrote:
Neglecting changing DOT fluid is the single biggest reason for replacing
brake and clutch cylinders and calipers, not to mention the risk of the
fluid boiling.

Why does not changing the fluid make it more likely to boil? I'd
understand if you said that any water in the fluid could turn to
steam... Or if I were convinced that any water content would cause
depression of boiling point...

Not in the least arguing against changing the fluid.

DOT fluid is hygroscopic, ie absorbs water. The longer you leave it,
the more water there is in it. Changing it means you get back to fluid
with no water in it.

And yes, water in it will cause problems other than corrosion - get it
hot and you do inded lose your brakes as things boil.

OK, OK but. The water can only come from the air in contact with the
fluid. In most modern vehicles this is the space above the fluid in the
reservoir. If the vehicle is unused, that bit of air will have lost all
the moisture it contained. There is no mechanism other than atmospheric
pressure changes to cycle fresh moisture containing air to that space.

In my view the 2 year fluid change must be based on an assumption about
the number of pedal operations and hence air changes in the reservoir.



--
Tim Lamb

On 18/05/2016 21:03, polygonum wrote:

I am delighted to read about absorbing water, creation of steam,
changing the fluid so it is dry, and the actual boiling points. All
relevant and some mentioned in my question/response. But none of them
seem to support the claim I was questioning: that not changing the brake
fluid makes the brake fluid itself more likely to boil.

If you were able to ensure that the brake fluid was unable to absorb any
water then yes, you would not have to change it so often.

However since that's apparently rather hard, you do need to change it,
because it does absorb the water and boils at a lower temperature.

On Wed, 18 May 2016 22:10:03 +0100, Clive George wrote:

I am delighted to read about absorbing water, creation of steam,
changing the fluid so it is dry, and the actual boiling points. All
relevant and some mentioned in my question/response. But none of them
seem to support the claim I was questioning: that not changing the
brake fluid makes the brake fluid itself more likely to boil.

If you were able to ensure that the brake fluid was unable to absorb any
water then yes, you would not have to change it so often.

However since that's apparently rather hard, you do need to change it,
because it does absorb the water and boils at a lower temperature.

Of course, an even easier option would be to use a non-hygroscopic
fluid...

But, no. It seems that's not an option. The one manufacturer who did have
gone back to DOT.

On 18/05/16 19:32, Adrian wrote:
On Wed, 18 May 2016 17:38:34 +0100, Phil L wrote:

For the sake of an extra £10 on the cost of a new car, I can't see why
they can't make them from copper in the first place, using steel is
outdated. Copper is the norm for replacement brake pipes.

No, it isn't.

Ebay results:

'Brake pipe copper' = 4,819

'Brake pipe Kunifer' = 621

So there's about 8 times as many copper pipes as kunifer.

Or a lot of people are incorrectly referring to cupro-nickel as "copper".

At least, I _hope_ that's what it is...


There is such stuff as pure copper brake pipe. Which turns out to be a
bad idea..

On 18/05/16 19:47, polygonum wrote:
On 18/05/2016 19:33, Adrian wrote:
Neglecting changing DOT fluid is the single biggest reason for replacing
brake and clutch cylinders and calipers, not to mention the risk of the
fluid boiling.

Why does not changing the fluid make it more likely to boil? I'd
understand if you said that any water in the fluid could turn to
steam... Or if I were convinced that any water content would cause
depression of boiling point...

That's basically it. https://en.wikipedia.org/wiki/Brake_fade

Not in the least arguing against changing the fluid.

On 18/05/2016 22:10, Clive George wrote:

However since that's apparently rather hard, you do need to change it,
because it does absorb the water and boils at a lower temperature.

WHAT boils at a lower temperature? The water in the brake fluid + water
mixture? Or the brake fluid itself?

I still cannot see why the boiling point of the brake fluid should
reduce. Please, please explain it to me.

I am genuinely happy that people are changing their brake fluid. I do
agree it is a good thing to do.

--
Rod

On 18/05/2016 22:13, Adrian wrote:
Of course, an even easier option would be to use a non-hygroscopic
fluid...

But, no. It seems that's not an option. The one manufacturer who did have
gone back to DOT.

Who was that? And what did they use - silicone?

--
Rod

On 18/05/16 21:03, polygonum wrote:
On 18/05/2016 20:45, Adrian wrote:
On Wed, 18 May 2016 20:36:04 +0100, Clive George wrote:

Neglecting changing DOT fluid is the single biggest reason for
replacing brake and clutch cylinders and calipers, not to mention the
risk of the fluid boiling.

Why does not changing the fluid make it more likely to boil? I'd
understand if you said that any water in the fluid could turn to
steam... Or if I were convinced that any water content would cause
depression of boiling point...

Not in the least arguing against changing the fluid.

DOT fluid is hygroscopic, ie absorbs water. The longer you leave it, the
more water there is in it. Changing it means you get back to fluid with
no water in it.

....and the boiling point of the water in the fluid is much lower than
the
boiling point of the fluid. Heat the fluid to 100degC or more, and the
water in the fluid boils, turning to steam. And steam is compressible.

The old DOT3 boils at 205degC. DOT4, the most common stuff today, boils
at 230degC. DOT5.1 boils at 260degC, as does the silicone DOT5, which
isn't miscible with the other three.

I am delighted to read about absorbing water, creation of steam,
changing the fluid so it is dry, and the actual boiling points. All
relevant and some mentioned in my question/response. But none of them
seem to support the claim I was questioning: that not changing the brake
fluid makes the brake fluid itself more likely to boil.


Because it absorbs water over time from the air (via the breather hole
in the cap for one).

On 18/05/16 22:24, polygonum wrote:
On 18/05/2016 22:10, Clive George wrote:

However since that's apparently rather hard, you do need to change it,
because it does absorb the water and boils at a lower temperature.

WHAT boils at a lower temperature? The water in the brake fluid + water
mixture? Or the brake fluid itself?

I still cannot see why the boiling point of the brake fluid should
reduce. Please, please explain it to me.

It matters not - if some fraction of the mix boils, the brakes fade. It
doesn't matter if the hydraulic fluid is OK, whilst the water is boiling
off.

I am genuinely happy that people are changing their brake fluid. I do
agree it is a good thing to do.

On 18/05/2016 22:33, Tim Watts wrote:
It matters not - if some fraction of the mix boils, the brakes fade. It
doesn't matter if the hydraulic fluid is OK, whilst the water is boiling
off.

It matters in that they are two different mechanisms. Either might be
quite able to let you crash your car because it won't stop.

--
Rod

On 18/05/2016 22:13, Adrian wrote:
On Wed, 18 May 2016 22:10:03 +0100, Clive George wrote:

I am delighted to read about absorbing water, creation of steam,
changing the fluid so it is dry, and the actual boiling points. All
relevant and some mentioned in my question/response. But none of them
seem to support the claim I was questioning: that not changing the
brake fluid makes the brake fluid itself more likely to boil.

If you were able to ensure that the brake fluid was unable to absorb any
water then yes, you would not have to change it so often.

However since that's apparently rather hard, you do need to change it,
because it does absorb the water and boils at a lower temperature.

Of course, an even easier option would be to use a non-hygroscopic
fluid...

But, no. It seems that's not an option. The one manufacturer who did have
gone back to DOT.

Over in bike-land, disks seem to be a mix of DOT and oil. Shimano and
Magura do oil (though Shimano claim theirs is super-special), Hope and
Hayes DOT. Much as I would love to support my local bike part maker
(Hope factory 20 miles from here), I wouldn't necessarily get another
one of their disks, purely because of the fluid. I think I've been
spoiled by the green stuff :-)

On 18/05/2016 22:53, polygonum wrote:
On 18/05/2016 22:33, Tim Watts wrote:
It matters not - if some fraction of the mix boils, the brakes fade. It
doesn't matter if the hydraulic fluid is OK, whilst the water is boiling
off.

It matters in that they are two different mechanisms. Either might be
quite able to let you crash your car because it won't stop.

No, it doesn't matter. The important thing is the boiling temperature of
the mix. The presence of the water renders the hydraulic fluid "not ok".

If you remove the water, yes, the boiling point of the brake fluid will
go back up. But that's hard.

I still cannot see why the boiling point of the brake fluid should
reduce. Please, please explain it to me.

Presumably the concept of a mixture changing the boiling point isn't
that odd to you? Adding salt to water raises the boiling point, adding
alcohol lowers it. Same general concept.

http://www.epicbleedsolutions.com/bl...s-mineral-oil/

has a nice graph.

FWIW the non-hygroscopic brake fluid Adrian mentioned is Citroen LHM.
It's less finicky than DOT, though the mechanism for using it is
different too - the force for the brakes comes from a pump + gas
pressurised reservior (accumulator sphere), not your foot. The pedal
just opens a valve.
I've not had anything else for quite a few years now :-)

polygonum wrote
Adrian wrote

Neglecting changing DOT fluid is the single biggest
reason for replacing brake and clutch cylinders and
calipers, not to mention the risk of the fluid boiling.

Why does not changing the fluid make it more likely to boil?

Because without the water in it, it isnt going to boil.

I'd understand if you said that any water
in the fluid could turn to steam...

That's just hair splitting about the use of the word boil.

Or if I were convinced that any water content
would cause depression of boiling point...

Ditto.

Not in the least arguing against changing the fluid.

"polygonum" wrote in message
...
On 18/05/2016 20:45, Adrian wrote:
On Wed, 18 May 2016 20:36:04 +0100, Clive George wrote:

Neglecting changing DOT fluid is the single biggest reason for
replacing brake and clutch cylinders and calipers, not to mention the
risk of the fluid boiling.

Why does not changing the fluid make it more likely to boil? I'd
understand if you said that any water in the fluid could turn to
steam... Or if I were convinced that any water content would cause
depression of boiling point...

Not in the least arguing against changing the fluid.

DOT fluid is hygroscopic, ie absorbs water. The longer you leave it, the
more water there is in it. Changing it means you get back to fluid with
no water in it.

....and the boiling point of the water in the fluid is much lower than
the
boiling point of the fluid. Heat the fluid to 100degC or more, and the
water in the fluid boils, turning to steam. And steam is compressible.

The old DOT3 boils at 205degC. DOT4, the most common stuff today, boils
at 230degC. DOT5.1 boils at 260degC, as does the silicone DOT5, which
isn't miscible with the other three.

I am delighted to read about absorbing water, creation of steam, changing
the fluid so it is dry, and the actual boiling points. All relevant and
some mentioned in my question/response. But none of them seem to support
the claim I was questioning: that not changing the brake fluid makes the
brake fluid itself more likely to boil.

He didnt say anything about the brake fluid itself boiling, he JUST said
that the brake fluid with absorbed water boils, and that is what it does.

"polygonum" wrote in message
...
On 18/05/2016 22:33, Tim Watts wrote:
It matters not - if some fraction of the mix boils, the brakes fade. It
doesn't matter if the hydraulic fluid is OK, whilst the water is boiling
off.

It matters in that they are two different mechanisms.

Nope, it is always the WATER boiling.

Either might be quite able to let you crash your car because it won't
stop.

It is always the WATER boiling.

On Wednesday, 18 May 2016 17:59:54 UTC+1, jim wrote:
Tim Lamb Wrote in message:
In message , jim
writes

Ford seem to think their brake fluid absorbs water from the air and

it does. It's hygroscopic and the systems aren't sealed.

require a 2 year change!

2 years seems a little keen, but it does need changing

Well the regular stuff is hygroscopic but whether it can
conceivably absorb enough to do any bother is a moot point!

Not much moot about failed brake calipers.


NT

On Wednesday, 18 May 2016 18:15:19 UTC+1, The Natural Philosopher wrote:
On 18/05/16 17:45, Tim Lamb wrote:
In message , The Natural Philosopher
writes
On 18/05/16 12:39, Tim Lamb wrote:

I think a limited mileage, stored under cover slightly corroded pipe is
not going fail totally in 12 months.

Light surface pitting doesn't cause failure, the pipe's thick. But it will at some point.

The point is there is no 'partial failure' mode with brakes. Either the
pipes hold up to the pressure, or you have either no brakes, or, if its
a dual master cylinder, one diagonal pair of brakes only.

FWIW there was also an arrangement where vehicles had dual circuit brakes yet failure of one circuit caused 100% failure on all wheels. My Y reg car had that. If you drive an old car you might have that setup. (Y at the end not the beginning.)


And all there is left is a hand brake and the engine braking.

First thing to do is pump the pedal. It often works.

Ive been lucky. Ive had front suspension fail, and brakes fail and both
were at low speed.

Ive also had a bonnet blow up in my face at 70mph in the fast lane of
the A1. Not so nice.

Funny how things change. I've driven things no-one would put on the road nowadays.


NT

On Wednesday, 18 May 2016 19:34:01 UTC+1, Adrian wrote:
On Wed, 18 May 2016 17:59:55 +0100, jim wrote:

Ford seem to think their brake fluid absorbs water from the air and
require a 2 year change!

Well the regular stuff is hygroscopic but whether it can
conceivably absorb enough to do any bother is a moot point!

It can, and it does - and it should be changed at two-year intervals.

Neglecting changing DOT fluid is the single biggest reason for replacing
brake and clutch cylinders and calipers, not to mention the risk of the
fluid boiling.

Speaking of boiling, look up Cuban brake fluid. Water, alcohol, sugar! And a dash of shampoo.


NT

On Thu, 19 May 2016 00:50:56 +0100, Clive George wrote:

FWIW the non-hygroscopic brake fluid Adrian mentioned is Citroen LHM.
It's less finicky than DOT, though the mechanism for using it is
different too - the force for the brakes comes from a pump + gas
pressurised reservior (accumulator sphere), not your foot. The pedal
just opens a valve.

It doesn't always... There are normal master cylinder braking systems
that use LHM...

Clive George a écrit :
If you were able to ensure that the brake fluid was unable to absorb any
water then yes, you would not have to change it so often.

However since that's apparently rather hard, you do need to change it,
because it does absorb the water and boils at a lower temperature.

No, it is not that difficult...

A manufacturer would simply need to seal the reservoir breather with a
flexible diaphram. Most of the moisture ingress to the fluid enters the
fluid via the breather in the reservoir cap.

My clutch hydraulics are described as 'sealed for life', supposedly no
need to change the fluid unless a part fails. Motocycles also use a
diaphram seal in the clutch and brake reservoirs.

On 18/05/16 19:47, polygonum wrote:
On 18/05/2016 19:33, Adrian wrote:
Neglecting changing DOT fluid is the single biggest reason for replacing
brake and clutch cylinders and calipers, not to mention the risk of the
fluid boiling.

Why does not changing the fluid make it more likely to boil? I'd
understand if you said that any water in the fluid could turn to
steam... Or if I were convinced that any water content would cause
depression of boiling point...


Your first idea is the right one. The water in the fluid turns to steam,
and that means a huge increase in elasticity in the fluid, and soft or
non existent brakes.

The simple way to say that is 'boiling brake fluid'


Not in the least arguing against changing the fluid.

It is a good idea. I'd say 5-20 years rather than 2 though.

But 2 is good from the POV of corrosion. Ive replaced cylinders and so
on back in the day and indeed more recently and corrosion is what causes
your cylinders to fail. Whether brake fluid change every 2 years is
cheaper than a calliper after 10 is a moot point though.


--
"I guess a rattlesnake ain't risponsible fer bein' a rattlesnake, but ah
puts mah heel on um jess the same if'n I catches him around mah chillun".

a écrit :
FWIW there was also an arrangement where vehicles had dual circuit brakes yet
failure of one circuit caused 100% failure on all wheels. My Y reg car had
that. If you drive an old car you might have that setup. (Y at the end not
the beginning.)

Back in the bad old days, I had a company car's single circuit brakes
fail on a hill down slope, on a back road, in Wales. Remember they only
fail when you use and need them. Not fun decending a hill with no
brakes. I put the handbrake on, used the lowest gear, but neither
enough to slow down, so I had to run it along a soft hedge to slow it
down.

I now habitually apply maximum pressure on the pedal, with the engine
running and whilst stood. That pressure will be far higher than you
would achieve in normal braking and is a better, more conclusive test
than looking at the pipes. No one can inspect the entire length of the
pipes for defects.

Clean them up, oil them, leave it to soak in, then grease them. If you
can then add some of that small, split electrical tube (commonly used
on car wiring), at the more exposed sections - all the better.

On 18/05/16 21:03, polygonum wrote:
But none of them
seem to support the claim I was questioning: that not changing the brake
fluid makes the brake fluid itself more likely to boil.

If you have a true mixture of water & hydraulic fluid, and it boils (the
solution) is that brake fluid boiling, the water boiling or the mixture
boiling?

I think you are just as lacking in understanding as the person who said
casually 'the brake fluid boils'.

The fluid in the brakes does indeed boil.



--
€œSome people like to travel by train because it combines the slowness of
a car with the cramped public exposure of €¨an airplane.€�

Dennis Miller

Tim Lamb wrote:
In message , Andrew Mawson
writes
"Tim Lamb" wrote in message
...

OK so it is overdue for an MOT. Probably done 1000 miles in the
year, barn stored.

Couple of advisories on last years.... brake pipes slightly corroded
near flex hose joint and inner side walls slightly deteriorated on
rear tyres.

Not much I can do about the tyres but wire brush off any brake pipe
rust and coat with..?


Wire brush off and replace with - NEW BRAKE PIPE ! - you may be
driving behind me

Vauxhall Zafiras don't go all that fast:-)

They don't need to if you hit a pedestrian or a child. I agree
with Andrew, replace them with copper.

The Natural Philosopher wrote:
On 18/05/16 21:03, polygonum wrote:
But none of them
seem to support the claim I was questioning: that not changing the brake
fluid makes the brake fluid itself more likely to boil.

If you have a true mixture of water & hydraulic fluid, and it boils (the
solution) is that brake fluid boiling, the water boiling or the mixture
boiling?

I think you are just as lacking in understanding as the person who said
casually 'the brake fluid boils'.

The fluid in the brakes does indeed boil.

That's my understanding of how a genuine solution 'boils'. There's no
separate boiling of the two constituents at different temperatures,
the boiling point is some new value which I guess is usually between
the boiling temperatures of the two constituents.

E.g. add salt to water, it dissolves and the boiling point of the
resultant solution is higher than that of pure water.

So I would guess with brake fluid when you add water the boiling point
reduces somewhat but what *doesn't* happen is that the water in the
solution boils at 100 degress Celsius.

--
Chris Green
·

Tim Lamb wrote:
In message , The Natural Philosopher
writes
On 18/05/16 12:39, Tim Lamb wrote:
OK so it is overdue for an MOT. Probably done 1000 miles in the year,
barn stored.

Couple of advisories on last years.... brake pipes slightly corroded
near flex hose joint and inner side walls slightly deteriorated on rear
tyres.

Not much I can do about the tyres but wire brush off any brake pipe
rust
and coat with..?

No, get the bloody things replaced. I've had brake failure..

Regular event on early Minis. Usually snatchy brakes from corroded
cylinders though.

I think a limited mileage, stored under cover slightly corroded pipe
is not going fail totally in 12 months.

I'll report what they have to say.




Corroded pipes, stored in a damp environment will decay at quite a
fast rate. I've just had a case where the drum brakes seized due to
rust, where the car is stored in a heated garage. There is enough
moisture around to do damage.

On 18/05/16 21:25, Harry Bloomfield wrote:
jim a écrit :
Tim Lamb Wrote in message:
OK so it is overdue for an MOT. Probably done 1000 miles in the year,
barn stored.

Couple of advisories on last years.... brake pipes slightly corroded
near flex hose joint and inner side walls slightly deteriorated on
rear tyres.

Not much I can do about the tyres but wire brush off any brake pipe
rust and coat with..?

Grease?

I agree, the thickest most waterproof grease you can lay your hands on.


I talked to the MOT cahp at te grafe.

What they do, is wash off all te grease and even brush the pipes with a
wire brush to see if the corrosion is severe enough to warrant failure.

The ministry approved chap who retested my car after a garage tried to
use the MOT to scam me, said that they are within their rights to fail
anything they cant tell ought to pass as well.

(By the way, you are within your rights to remove a car from a garage
even if it has no MOT, and they have failed it, if the purpose of taking
it there was to get an MOT, and if it still *has* an MOT, then retaining
it on the grounds that it is 'unsafe' until said garage spends several
thousand on it (unnecessarily) is actually a criminal offence of
extortion).



Check it is ONLY surface rust, clean it off, paint it with oil, then
grease. This is as advised by my MOT inspector and it said it is no
reason for an inspector to be suspcious - they can feel the condition
easily through the grease.

Underseal will only seal in the moisure and rust - the rusting will
continue under the underseal, besides it is a reason for the MOT guy to
be suspcious.

Or fail it outright.

I think getting my rear brake pipes replaced last time was around £80.
I've done it myself when younger on a Saturday afternoon for about £20
including a brake flare tool.


A small price to pay - less than a tank of diesel then - for knowing
that they were sound, and that the brake fluid in the system had also
largely been flushed out.

--
The theory of Communism may be summed up in one sentence: Abolish all
private property.

Karl Marx

On 18/05/16 21:38, Tim Lamb wrote:
In message , Clive
George writes
On 18/05/2016 19:47, polygonum wrote:
On 18/05/2016 19:33, Adrian wrote:
Neglecting changing DOT fluid is the single biggest reason for
replacing
brake and clutch cylinders and calipers, not to mention the risk of the
fluid boiling.

Why does not changing the fluid make it more likely to boil? I'd
understand if you said that any water in the fluid could turn to
steam... Or if I were convinced that any water content would cause
depression of boiling point...

Not in the least arguing against changing the fluid.

DOT fluid is hygroscopic, ie absorbs water. The longer you leave it,
the more water there is in it. Changing it means you get back to fluid
with no water in it.

And yes, water in it will cause problems other than corrosion - get it
hot and you do inded lose your brakes as things boil.

OK, OK but. The water can only come from the air in contact with the
fluid. In most modern vehicles this is the space above the fluid in the
reservoir. If the vehicle is unused, that bit of air will have lost all
the moisture it contained. There is no mechanism other than atmospheric
pressure changes to cycle fresh moisture containing air to that space.

In my view the 2 year fluid change must be based on an assumption about
the number of pedal operations and hence air changes in the reservoir.

Most 'routine services' are based on some assumption or other.

Fuel filters, on account of fuel being more, or less, contaminated with
particles from more or less rusty tanks etc etc.

Air filters, on driving in more ore less dusty conditions..

Pollen filters, on actually using the internal ventilation system in the
spring and summer, rather than opening the windows.

Brake fluid and coolant changes are both based on the assumption that
the fluids will over time degrade and ultimately damage the systems they
are inside.

Whether the cost of replacing those system is less than thee
aaccumulated costs of changing the fluids, is a moot point.

I know at least one fleet car manager who would buy brand new Fords, run
them for around one year and about 80,000 miles without servicing them
AT ALL and then trade them.

Their value was not lessened by the fact the oil resembled tar, the
brakes were worn to a whisper, if they still worked, and the spark plugs
barely were able to generate a spark. All that counted was the body
looked good and the plate was a late one.









--
New Socialism consists essentially in being seen to have your heart in
the right place whilst your head is in the clouds and your hand is in
someone else's pocket.

On Thu, 19 May 2016 09:43:42 +0100, Harry Bloomfield wrote:

Clive George a écrit :
If you were able to ensure that the brake fluid was unable to absorb
any water then yes, you would not have to change it so often.

However since that's apparently rather hard, you do need to change it,
because it does absorb the water and boils at a lower temperature.

No, it is not that difficult...

A manufacturer would simply need to seal the reservoir breather with a
flexible diaphram. Most of the moisture ingress to the fluid enters the
fluid via the breather in the reservoir cap.

And that's exactly what often happens - especially on 4x4s and
motorbikes, where the master is more likely suffer direct water ingress.

It's still a good idea to change the fluid every two years.