Discussion:
How to garages change car brake fluid?
(too old to reply)
Michael Chare
2021-09-15 23:41:59 UTC
Permalink
What tools would a garage (main dealer) use to change the brake fluid in
a car? Do they have something that attaches to the resevoir and
supplies the new fluid at pressure so that the operator can let the old
fluid out of each caliper in turn?
Jim GM4DHJ ...
2021-09-16 05:56:54 UTC
Permalink
Post by Michael Chare
What tools would a garage (main dealer) use to change the brake fluid in
a car?  Do they have something that attaches to the resevoir and
supplies the new fluid at pressure so that the operator can let the old
fluid out of each caliper in turn?
never change brake fluid on any car over 50 years....a myth
SH
2021-09-16 06:56:49 UTC
Permalink
Post by Jim GM4DHJ ...
Post by Michael Chare
What tools would a garage (main dealer) use to change the brake fluid
in a car?  Do they have something that attaches to the resevoir and
supplies the new fluid at pressure so that the operator can let the
old fluid out of each caliper in turn?
never change brake fluid on any car over 50 years....a myth
Brake fluid is hygroscopic.... over time it abosrbs water from the air.
Thus the absorbed water diffuses through the hydraulic pipework right
down to the caliper pistons.

This leads to a few issues.

1. It can cause aqueous corrosion of metal parts within.

2. If any metal parts that are corroding happen to form a surface
against a rubber o ring, the sealing surface is no longer smooth, and
thus the corroded metal surface literally abrdaes the rubebr seal liek
sandpaper, causing a fluid leak.

3. Under heavy braking, the brakes and caliper can get hot. if the brake
fluid itself beomces hotter than 100 deg C, that entrained water then
boils off forming gas molecules. This affects the braking system
performance just when you need it most if you are trying to brake heavily.
Harry Bloomfield, Esq.
2021-09-16 09:16:51 UTC
Permalink
Brake fluid is hygroscopic.... over time it abosrbs water from the air. Thus
the absorbed water diffuses through the hydraulic pipework right down to the
caliper pistons.
This leads to a few issues.
1. It can cause aqueous corrosion of metal parts within.
2. If any metal parts that are corroding happen to form a surface against a
rubber o ring, the sealing surface is no longer smooth, and thus the corroded
metal surface literally abrdaes the rubebr seal liek sandpaper, causing a
fluid leak.
3. Under heavy braking, the brakes and caliper can get hot. if the brake
fluid itself beomces hotter than 100 deg C, that entrained water then boils
off forming gas molecules. This affects the braking system performance just
when you need it most if you are trying to brake heavily.
+1
bert
2021-09-16 19:58:52 UTC
Permalink
In article <shuprh$1ir9$***@gioia.aioe.org>, SH <***@spam.com>
writes
Post by SH
Post by Jim GM4DHJ ...
Post by Michael Chare
What tools would a garage (main dealer) use to change the brake
fluid in a car?  Do they have something that attaches to the
resevoir and supplies the new fluid at pressure so that the operator
can let the old fluid out of each caliper in turn?
never change brake fluid on any car over 50 years....a myth
Brake fluid is hygroscopic.... over time it abosrbs water from the air.
Thus the absorbed water diffuses through the hydraulic pipework right
down to the caliper pistons.
Not any more.
Post by SH
This leads to a few issues.
1. It can cause aqueous corrosion of metal parts within.
2. If any metal parts that are corroding happen to form a surface
against a rubber o ring, the sealing surface is no longer smooth, and
thus the corroded metal surface literally abrdaes the rubebr seal liek
sandpaper, causing a fluid leak.
3. Under heavy braking, the brakes and caliper can get hot. if the
brake fluid itself beomces hotter than 100 deg C, that entrained water
then boils off forming gas molecules. This affects the braking system
performance just when you need it most if you are trying to brake heavily.
--
bert
alan_m
2021-09-16 10:21:44 UTC
Permalink
Post by Jim GM4DHJ ...
Post by Michael Chare
What tools would a garage (main dealer) use to change the brake fluid
in a car?  Do they have something that attaches to the resevoir and
supplies the new fluid at pressure so that the operator can let the
old fluid out of each caliper in turn?
never change brake fluid on any car over 50 years....a myth
A lot of people don't change the fluid but the manufactures recommend it.
--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk
SH
2021-09-16 11:02:16 UTC
Permalink
Post by alan_m
Post by Jim GM4DHJ ...
Post by Michael Chare
What tools would a garage (main dealer) use to change the brake fluid
in a car?  Do they have something that attaches to the resevoir and
supplies the new fluid at pressure so that the operator can let the
old fluid out of each caliper in turn?
never change brake fluid on any car over 50 years....a myth
A lot of people don't change the fluid but the manufactures recommend it.
its usually every two years....
Andrew
2021-09-16 15:40:20 UTC
Permalink
Post by alan_m
Post by Jim GM4DHJ ...
Post by Michael Chare
What tools would a garage (main dealer) use to change the brake fluid
in a car?  Do they have something that attaches to the resevoir and
supplies the new fluid at pressure so that the operator can let the
old fluid out of each caliper in turn?
never change brake fluid on any car over 50 years....a myth
A lot of people don't change the fluid but the manufactures recommend it.
I personally think that it should be changed when you have new pads
because winding the caliper pistons back forces old fluid back
through the ABS unit into the master cylinder.
newshound
2021-09-16 07:41:13 UTC
Permalink
Post by Michael Chare
What tools would a garage (main dealer) use to change the brake fluid in
a car?  Do they have something that attaches to the resevoir and
supplies the new fluid at pressure so that the operator can let the old
fluid out of each caliper in turn?
I am only guessing, but I have always assumed they used the professional
equivalent of the old "DIY" Eezibleed which is just as you described. A
bottle for new fluid, connected to a replacement filler cap of the
reservoir, and pressurised with air to 5 or 10 psi. Then each brake
nipple opened in turn until the fluid runs "clear". Usually starting
with the brake furthest from the master cylinder.
SH
2021-09-16 08:15:01 UTC
Permalink
Post by newshound
Post by Michael Chare
What tools would a garage (main dealer) use to change the brake fluid
in a car?  Do they have something that attaches to the resevoir and
supplies the new fluid at pressure so that the operator can let the
old fluid out of each caliper in turn?
I am only guessing, but I have always assumed they used the professional
equivalent of the old "DIY" Eezibleed which is just as you described. A
bottle for new fluid, connected to a replacement filler cap of the
reservoir, and pressurised with air to 5 or 10 psi. Then each brake
nipple opened in turn until the fluid runs "clear". Usually starting
with the brake furthest from the master cylinder.
I have seen vacuum versions where the fluid is sucked out under a vacuum
from an opened bleed nipple on the calliper/psiton.

The brake fluid reservoir screw cap is replaced with one with a tube
connected to it which then goes into a container of fresh brake fluid.

Vacuum is preferred over pressure as the effects of a leak is less....
i.e. the system would suck in air via a leak whereas in a pressurised
system, hydraulic fluid would be sprayed everywhere!

S
newshound
2021-09-16 11:16:53 UTC
Permalink
Post by SH
Post by newshound
Post by Michael Chare
What tools would a garage (main dealer) use to change the brake fluid
in a car?  Do they have something that attaches to the resevoir and
supplies the new fluid at pressure so that the operator can let the
old fluid out of each caliper in turn?
I am only guessing, but I have always assumed they used the
professional equivalent of the old "DIY" Eezibleed which is just as
you described. A bottle for new fluid, connected to a replacement
filler cap of the reservoir, and pressurised with air to 5 or 10 psi.
Then each brake nipple opened in turn until the fluid runs "clear".
Usually starting with the brake furthest from the master cylinder.
I have seen vacuum versions where the fluid is sucked out under a vacuum
from an opened bleed nipple on the calliper/psiton.
The brake fluid reservoir screw cap is replaced with one with a tube
connected to it which then goes into a container of fresh brake fluid.
Vacuum is preferred over pressure as the effects of a leak is less....
i.e. the system would suck in air via a leak whereas in a pressurised
system, hydraulic fluid would be sprayed everywhere!
S
Well not really sprayed everywhere, if (as was common) you connected
your easybleed to a tyre to provide the pressure, it was recommended
that you dropped the pressure to 1 bar or so, because plastic master
cylinder reservoirs are not designed to take pressure! Yes, it would be
messy if you "blew up" a master cylinder, but the flow rate at the
nipple or any other normal leak site is not very large.

I've never seen a vacuum system, but no reason why it should not work.
Except of course that every seal in the system is designed for positive
pressure, so negative pressure has the potential to draw air in at each
seal, possibly with dust contamination. With "healthy" seals there
should be enough pressure from the elasticity to make sure this does not
happen.
Harry Bloomfield, Esq.
2021-09-16 09:15:38 UTC
Permalink
What tools would a garage (main dealer) use to change the brake fluid in a
car? Do they have something that attaches to the resevoir and supplies the
new fluid at pressure so that the operator can let the old fluid out of each
caliper in turn?
Some reverse flush - pump it in at the bleed nipple, a turkey baster to
suck it out of the master reservoir.

Others might use a pressurised 'easybleed' attached to the master
reservoir, bleeding at the nipples.
www.GymRatZ.co.uk
2021-09-16 09:16:25 UTC
Permalink
Post by Michael Chare
What tools would a garage (main dealer) use to change the brake fluid in
a car?  Do they have something that attaches to the resevoir and
supplies the new fluid at pressure so that the operator can let the old
fluid out of each caliper in turn?
When I was an apprentice some... nearly 40 years ago we had a device
called an "EZ-Bleed" which you'd fill up the bottle with fresh fluid,
attach one pipe to the fluid reservoir via one of the selection of
included (piped) caps and the other end connected to a wheelbarrow tyre
via regular foot-pump type valve.

Operation was as you describe, clear plastic tube on the bleed nipple
going into a jar to catch the dirty stuff.

Worked really well and didn't require any mower supplies, vacuum pumps etc.
jkn
2021-09-16 09:34:07 UTC
Permalink
Post by www.GymRatZ.co.uk
Post by Michael Chare
What tools would a garage (main dealer) use to change the brake fluid in
a car? Do they have something that attaches to the resevoir and
supplies the new fluid at pressure so that the operator can let the old
fluid out of each caliper in turn?
When I was an apprentice some... nearly 40 years ago we had a device
called an "EZ-Bleed" which you'd fill up the bottle with fresh fluid,
attach one pipe to the fluid reservoir via one of the selection of
included (piped) caps and the other end connected to a wheelbarrow tyre
via regular foot-pump type valve.
Operation was as you describe, clear plastic tube on the bleed nipple
going into a jar to catch the dirty stuff.
Worked really well and didn't require any mower supplies, vacuum pumps etc.
I think I remember doing that as a lad, as an occasional 'chore' with my Dad
on our old Cortina. I inherited the kit, can't remember if I still have it...
Steve Walker
2021-09-16 15:25:10 UTC
Permalink
Post by jkn
Post by www.GymRatZ.co.uk
Post by Michael Chare
What tools would a garage (main dealer) use to change the brake fluid in
a car? Do they have something that attaches to the resevoir and
supplies the new fluid at pressure so that the operator can let the old
fluid out of each caliper in turn?
When I was an apprentice some... nearly 40 years ago we had a device
called an "EZ-Bleed" which you'd fill up the bottle with fresh fluid,
attach one pipe to the fluid reservoir via one of the selection of
included (piped) caps and the other end connected to a wheelbarrow tyre
via regular foot-pump type valve.
Operation was as you describe, clear plastic tube on the bleed nipple
going into a jar to catch the dirty stuff.
Worked really well and didn't require any mower supplies, vacuum pumps etc.
I think I remember doing that as a lad, as an occasional 'chore' with my Dad
on our old Cortina. I inherited the kit, can't remember if I still have it...
I certainly have one in the garage, but if you have a second person
available to press and release the pedal on demand, that is often
quicker and easier.

The Easibleed has the advantage of one person operation and continuous
flow that can make particularly hard to bleed systems clear more easily.

Vacuum systems (which I have never tried) are supposedly better and
getting the bubbles out of the most difficult systems.
ARW
2021-09-18 04:06:51 UTC
Permalink
Post by Steve Walker
I certainly have one in the garage, but if you have a second person
available to press and release the pedal on demand, that is often
quicker and easier.
As long as you keep enough fluid in the tank:-)

BTDTGTTS



--

Adam
Dave Plowman (News)
2021-09-18 11:44:17 UTC
Permalink
Post by ARW
Post by Steve Walker
I certainly have one in the garage, but if you have a second person
available to press and release the pedal on demand, that is often
quicker and easier.
As long as you keep enough fluid in the tank:-)
BTDTGTTS
The EaziBleed has an additional reservoir. Which automatically tops up the
main one. But you don't have to use it.
--
*What was the best thing before sliced bread? *

Dave Plowman ***@davenoise.co.uk London SW
To e-mail, change noise into sound.
soup
2021-09-16 09:42:42 UTC
Permalink
Post by Michael Chare
What tools would a garage (main dealer) use to change the brake fluid in
a car?  Do they have something that attaches to the resevoir and
supplies the new fluid at pressure so that the operator can let the old
fluid out of each caliper in turn?

Tim+
2021-09-16 17:51:19 UTC
Permalink
Post by Michael Chare
What tools would a garage (main dealer) use to change the brake fluid in
a car? Do they have something that attaches to the resevoir and
supplies the new fluid at pressure so that the operator can let the old
fluid out of each caliper in turn?
Professionally I think it is usually done with a positive pressure system
(like this
https://www.amazon.co.uk/dp/B095LFTG9T/ref=cm_sw_em_r_mt_dp_A3JJBM24BDA0P8A6KMMR
)

Negative pressure systems risk sucking air past seals not designed to
resist negative pressures.

The old fashioned way involves two people, one pumping the pedal and one
monitoring the flow from the bleed nipple. The big downside of this method
is that it’s too easy to floor the brake pedal and push the piston past
it’s normal range of travel where there may be ring of corrosion or debris
resulting in seal damage.

I was most unhappy with my VW dealer when they fecked my master cylinder
after a fluid change.

Tim
--
Please don't feed the trolls
Dave Plowman (News)
2021-09-17 15:03:37 UTC
Permalink
Post by Michael Chare
What tools would a garage (main dealer) use to change the brake fluid in
a car? Do they have something that attaches to the resevoir and
supplies the new fluid at pressure so that the operator can let the old
fluid out of each caliper in turn?
There are two ways. A vacuum pump used at each bleed nipple. Or you
pressurize the fluid reservoir.

I have both here (DIY versions) Eazibleed, which uses pressure from a tyre
(reduced to about 20psi) is the best. But do make sure you connect it
properly, as a leak can result in fluid squirting everywhere.
--
*A computer once beat me at chess, but it was no match for me at kickboxing.

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