Why flush brake system?

[nrs2001]

They tell me that I need to flush my brake system and coolant system.
Both of these systems are closed! Why would you need to flush a closed
system. They are not under the same pressure and abuse as oil, I change
my oil every 3000 miles. Those other "flushes" sound like a way for
Subaru to get more money?

Any advice. Is Subaru different from ALL the other different cars in
the world.

Nick

 

[Clive - Selectron]

They tell me that I need to flush my brake system and coolant system.
Both of these systems are closed! Why would you need to flush a closed
system. They are not under the same pressure and abuse as oil, I change
my oil every 3000 miles. Those other "flushes" sound like a way for
Subaru to get more money?

Any advice. Is Subaru different from ALL the other different cars in
the world.

Nick

Brake fluid is hygroscopic...it absorbs water
and must be changed at the recommended intervals.
Sludge builds up in cooling systems and must be flushed
as per the book.
Neither system is 'closed'
All cars are the same....and if you disregard the book
you'll learn the hard way when you run out of brakes
and the cooling system blows up.
C

 

[G.J.H. Jørgensen]

It's necessary for ALL cars!
Brake fluid attracts water - and the system is NOT closed - there is a
necessary little hole in the cap of the brake fluid beholder.
Water vaporises when heated - but the vapor is strongly pressable - with too
much water in your brake fluid braking is even impoosible.
And then there is the question of corrosion - and I have had a brake piston
corroded in its cylinder - I was driving at 130 km/hr on a German motorway
when the rear brake of my car (a Renault) slammed shut .... not nice!

Your coolant liquid deteriorates because of the combustion system and
aging - there's no need for a head gasket to blow up to get your coolant
liquid contaminated with oil and smear over a number of years.
My advice: Renew braking fluid and coolant every two years on ANY car make,
or every 60,000 miles.

George

 

[Rick Courtright]

Any advice. Is Subaru different from ALL the other different cars in
the world.

Hi,

At the risk of offending someone, Subaru is just like all the cars on
the market in the "flush brake fluid" and "flush coolant" departments.
The other guys already explained why.

Rick

 

[Jim Stewart]

:




Hi,

At the risk of offending someone, Subaru is just like all the cars on
the market in the "flush brake fluid" and "flush coolant" departments.
The other guys already explained why.

All you have to do is watch someone flush your brake
fluid to be a believer. It starts coming out of the
system the color of dark pancake syrup and ends up
clear as the new fluid gets to the calipers.

One of the few maintenance procedures that I actually
find rewarding at the time.

 

[Kurt Krueger]

Brake fluid is hygroscopic...it absorbs water
and must be changed at the recommended intervals.
Sludge builds up in cooling systems and must be flushed
as per the book.
Neither system is 'closed'
All cars are the same....and if you disregard the book
you'll learn the hard way when you run out of brakes
and the cooling system blows up.
C

Flushing of brakes was not common in the old days, but flushing of
radiators was. Much greater chance of rust/gunk causing trouble in
the radiator. On thing that I take exception to is the interval.
There are 5 year antifreeze products out there. Radiators have more
non rustable plastic parts. Antifreeze has better rust inhibitors.
A flush when the coolent is replaced should be sufficient.

If your Subaru book has a recommended flush interval, I'd go with
that. Note that your dealer is likely to have a much shorter
recommended interval.

And ... I used to never flush brake fluid. That concept didn't exist
in the 1970 when I started driving. Never ran out of brakes. But
I paid attention ... small leaks would appear and that was the old way
to know that something needed replacement. Usually at the same time
the shoes/pads were replaced.

My personal opinion ... flushing brake fluid isn't a bad idea. But it's
also a good profit center for the dealer. And they like to use
scare tactics. Use your good judgement as to how often.

 

[Jim Stewart]

And ... I used to never flush brake fluid. That concept didn't exist
in the 1970 when I started driving. Never ran out of brakes. But
I paid attention ... small leaks would appear and that was the old way
to know that something needed replacement. Usually at the same time
the shoes/pads were replaced.

My personal opinion ... flushing brake fluid isn't a bad idea. But it's
also a good profit center for the dealer. And they like to use
scare tactics. Use your good judgement as to how often.

Yes, and I remember fighting leaky slave
cylinders in the 70's and leaky calipers
in the 80's. Haven't had any problems
with them since I started bleeding the
brakes after each pad change.

 

[Clive]

Was your 1970's car a high performance model
with discs with suberb (think 'heat') brakes?
1970 and 2006 cars are different in every technical respect
and what was OK then sure ain't now and clearly the poster
does not possess good judgement in this area.
Any other approach except by the book is dangerous penny-pinching.
-C-

 

[Rick Courtright]

And ... I used to never flush brake fluid. That concept didn't exist
in the 1970 when I started driving. Never ran out of brakes. But

Hi,

Don't forget back in the '60s amd '70s how much more frequently we
rebuilt or replaced cylinders, both master and slave. You didn't think
about "flushing" the brakes as a separate drill cuz there was usually
enough frequency of "other" brake service to keep things cleaned out and
"fresh" reasonably well.

Rick

 

[mike]

I agree. I flushed the brakes on my legacy the other month, and the first
bit of fluid out of each caliper was darker and heavier,. you could see a
distinct layer of caliper fuid in bottom of the container. All fluids
degrade over time and at a cost of $50 it worth doing.

Cheers
Mike

 

[Edward Hayes]

I think intelligent people would read their owner mantancence manual.
Most manufactures recommend 3years/36,000 miles for most brake &
cooling system service.

 

[AS]

I agree:

Newer systems are almost closed. Cylinder tanks now have rubber bellows
under the caps that allow for expansion or brake pad/shoes wear
compensation of the brake fluid level, keeping the air on the outer side
of the bellows. The thing is that there is always wear due to the
rubbing parts inside the cylinders. That wear results in microscopic
particles being in the brake fluid and it does not get any better with
time. Flushing guarantees that the system will last as long as possible.

For the cooling system I recommend replacing the coolant with water and
Zerex antifreeze (the green one that comes in a white container). I did
that when my 94 maxima had 10k miles on it. Recently at 114k miles, i
replaced the water pump because it began dripping. The coolant that
came out when draining the system was perfect in color, smell and
consistency. When I removed the pump, there were no rust traces
anywhere in the system, not even slight deposits in the radiator. I
never flushed the system since the initial change.

 

[Rick Courtright]

For the cooling system I recommend replacing the coolant with water and
Zerex antifreeze (the green one that comes in a white container). I

Hi,

No recommendation for antifreeze brand here (I don't buy into the "Brand
A is so much better than Brand B" arguments since I'd not be surprised
to find all of 'em come from the same vat!), but I DO recommend (as do
many) that you use DISTILLED water (some sources recommend "de-ionized"
which I believe is what they claim to use in the "pre-mix" stuff you can
buy at the auto parts store for way too much money!)

Rick

 

[mulder]

For the cooling system I recommend replacing the coolant with water and
Zerex antifreeze (the green one that comes in a white container). I did
that when my 94 maxima had 10k miles on it. Recently at 114k miles, i
replaced the water pump because it began dripping. The coolant that
came out when draining the system was perfect in color, smell and
consistency. When I removed the pump, there were no rust traces
anywhere in the system, not even slight deposits in the radiator. I
never flushed the system since the initial change.

What applies to Nissan does not apply to Subaru. Standard antifreeze
should not be used, and you can't go by color. The correct coolant for
Subarus is silicate and phospate free, many generic coolants do not
meet this requirement. Safe to use are the OEM stuff from the dealer,
Peak Global, and Prestone "All Makes All Models" (not their regular
stuff). The Peak and Prestone are both available in 50-50 premix form
so you don't have to worry about sourcing or adding water.

 

[nrs2001]

So they are out to get money, and most of the people on here work for
Subaru!

 

[Dmitriy]

If you don't believe us, do it yourself and compare the two fluids. You
will see how brown the brake fluid coming out of the calipers is
compared to the new stuff... and old coolant can be plain nasty
looking.

As for coolant, if you have a 1998-02 Subaru with a 2.5 liter engine,
you might have to put in the Subaru coolant conditioner to help prevent
head gasket problems and get a free repair if they do happen.

You will find people on here recommending OEM stuff a lot because, with
a few exceptions, Subaru OEM is just better quality and performance
than the stuff you can get at Autozone or Walmart.

And no, I don't work for Subaru.

 

[mulder]

Please note that I am not specifically recommending the OEM coolant,
and no I do not work for Subaru either. I was just indicating that
only a specific type of coolant should be used, and the OEM was one of
the options. Personally I have not used OEM but I have used both the
Peak Global and Prestone universal coolants.
The conditioner was introduced by Subaru to address head gasket issues
in some of the older 2.5 engines, they now recommend it across the
board but I've never used it in my WRX.

 

[QX]

While you are at it, to do a complete job, don't forget the
power steering fluid. Although I wasn't prepared to flush the entire
system (not prepared technically), I did use a turkey baster to remove
all the old fluid from the reservoir, and refilled it with new.
The old stuff was really nasty looking. It probably would have been
better to drain the PS Cylinder, but I had no idea how to do so, and
didn't want to mess around with a high pressure side.

Does anyone know if using a silicon based brake fluid would be a
better idea if you plan to keep the car for years and years? Silicon
fluids are not hydroscopic. They cost more, but are they worth it?

 

[mulder]

While you are at it, to do a complete job, don't forget the
power steering fluid. Although I wasn't prepared to flush the entire
system (not prepared technically), I did use a turkey baster to remove
all the old fluid from the reservoir, and refilled it with new.
The old stuff was really nasty looking. It probably would have been
better to drain the PS Cylinder, but I had no idea how to do so, and
didn't want to mess around with a high pressure side.

Does anyone know if using a silicon based brake fluid would be a
better idea if you plan to keep the car for years and years? Silicon
fluids are not hydroscopic. They cost more, but are they worth it?

Silicone fluid (DOT 5) is not compatible with systems that have
already had glycol based fluid in them. The two do not mix and all the
seals in the system will be ruined if DOT 5 is used to replace DOT 3
or 4. In addition, DOT 5 cannot be used in systems with ABS due to
foaming.

 

[Dmitriy]

Silicone fluid (DOT 5) is not compatible with systems that have
already had glycol based fluid in them. The two do not mix and all the
seals in the system will be ruined if DOT 5 is used to replace DOT 3
or 4. In addition, DOT 5 cannot be used in systems with ABS due to
foaming.

The ONLY real advantage of DOT5 fluid over the previous DOT's is that
it does not dissolve paint. I believe that the fact that they are no
hydroscopic (don't absorb water) makes them even worse, because instead
of having the moisture evenly spread out, you have pockets form in the
brake system - not good.

Go with DOT3... you can get it for like $1.50 at Walmart for some good
synthetic stuff... you'll probably need 3 of the little bottles or so
for a complete bleed.