brake fluid change

I have a 99 Civic with 230k miles and I've never changed the brake fluid.
But I just read an article about moisture content decreasing the boiling
point of the fluid over time. Now I'm concerned about the master cylinder
because I've never changed the fluid. Any thoughts?

Pete

 

Any damage to the master cylinder from lack of maintenance is already
done. That said, changing the fluid now will most likely result in the
master cylinder failing, either at the conclusion of the change, or shortly
thereafter.

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It's a good idea.

dan

 

Brake fluid change is ALWAYS a good idea, even on cars that have been badly
neglected, like this one.

Get the dealer or another garage to do it. They have equipment that does
not endanger the master cylinder during bleeding.

 

there's not much danger to seals from the process - it's almost always
chemical. fresh fluid causes slight sizing change, and on worn seals,
that can cause leakage. for this mileage, if you're not doing the work
yourself, it's probably cost effective to simply replace.

 

Honda says differently.
http://www.tegger.com/hondafaq/misc/A011000.pdf

 

written locally, not in japan. bottom line - the cylinder needs to be
effective through the full stroke, any time, any reason. period. if
it's not, it needs to be replaced. besides, as you yourself show with
the internal condition of your own master cylinder rebuild on your web
site, the corrosion inhibitors in modern fluids pretty much prove this
to be ancient history.

 

Sounds like both Jim Beam and Tegger are right -- under different
circumstances.

Well eqiupped shops use pressure/vacuum bleeders. So the brake pedal
isn't pumped during the process. However, the brake pedal should be
depressed a little (past the vent port) so the area behind the seal
can be flushed. I think Jim meant how new, drier brake fluid affects
the old, well-moisturized rubber seals (e.g., shrinkage issue).

However, for the smaller or less well equipped shops that do pump the
pedal as in the manual method, not depressing the pedal all the way to
the floor should save the rubber seals.

 

Sure, the cost of a flush ~$100 is probably better applied towards a
new master cylinder. IIRC the Honda OEM online dealer sells for about
$100.

 

how? if the new fluid shrinks the seals, then not pumping them isn't
going to save them.

besides, the master cylinder /should/ work, new fluid, all the way,
regardless. imagine you cut a brake line, debris or whatever, and now
you only have one circuit working. suddenly, you're going to want to
use the "unused" portion of the master cylinder real damned quick, and
having that suddenly fail because you've never checked that it worked
all the way last time you bled the brakes could suddenly be just a
teensy weensy little bit inconvenient.

bleeding kits are for speed, convenience and one-man operation, not seal
preservation.

 

I agree that a properly maintained master cylinder should work it's
full usable bore. However, I also agree that brake fluid is
hydroscopic and it contributes to the bore corrosion problems
mentioned.

So in a poorly maintained master cylinder even with a protective
coated bore, I personally wouldn't count too much on the full use of
the backup hydraulic circuit, at least for too long

As far as rubber swell -- I was reading Tegger's site on his MC
repalcement. So I'll leave that to him.


From Valvoline's site, on master cylinder water damage:
http://www.valvoline.com/carcare/articleviewer.asp?pg=ccr20020401mc

"Water Damage
Master cylinder leaks are normally caused by corrosion within the
horizontal cylinder. Brake fluid is hydrostatic [sic], which means it
attracts water. The water in the brake fluid can cause rust pitting
inside the fluid cylinder resulting in fluid leaking past the rubber
plunger. Once this happens the only cure is a rebuild or master
replacement."

 

nor would i - but the point is, you want it to work that /one/ time you
need it to!

yeah, good one. that should read: "hygroscopic".

another reason to use aluminum cylinders - like honda do!



to labor the point, i've done many a brake job over the years, and yes,
i've seen many a master cylinder go south just a few weeks after fluid
change or bleeding. but here's the thing - that same thing can happen
when you bleed the system with a pressure kit and don't even /touch/ the
master cylinder. it's all a function of age and condition. if the
fluid in the master cylinder looks cloudy and black, the seals are
degrading and will soon leak. if the fluid turns brown, it's simply
moisture and can be replaced with no further worries. if i see black, i
replace or re-seal - no point messing about.

 

wrote in @w1g2000prk.googlegroups.com:

/I'm/ not right, HONDA is right.

The area behind the rear seal is in the open air, so you can't flush that.
The area behind the front seal has the fluid for the rear chamber. You
flush this area automatically when that circuit is bled.

 

And our cars are driven locally, not in Japan, so the page is most
definitely relevant.

And I'm unable to find any HSN mentions of seal shrinkage due to new
fluid, so I'm guessing Honda has found friction damage to be far more
prevalent than seal shrinkage.

Yes, but if the brakes have failed to the point that you need to rely on
the "last resort" fallback of the one working circuit, the entire system
needs later to be looked at and repaired by a professional (provided the
car didn't get wrecked), so MC condition is not the most important issue
right then. Brakes in that bad shape will likely need a replacement MC
anyway.

My brake fluid is changed every single year, as I also say in that page.

 

wrote in

Depends on the car. For my Integra, an OEM MC is about $350. An aftermarket
reman is about $75.

And if you replace the MC, the system needs to be bled anyway, so I don't
see how you'd save the labor charge for that.

 

as shown by the corrosion here?
http://www.tegger.com/hondafaq/mastercylinderreplace/disassembly/inside-master-cylinder-bore.jpg

why guess? seal swelling and shrinkage is such a known issue, it's part
of the spec to which brake fluids are manufactured.

with respect dude, if it's the only thing you have left after one
circuit has failed, it most definitely /is/ important.

i've been saying that all along.

as you should.

 

you save by not having the job done twice. just changing the fluid,
then coming back a month later because the cylinder's gone is a waste of
money.

 

The fluid in that cylinder was changed EVERY YEAR. Corrosion happens when
you NEVER change it. That photo is a testament to the effects of frequent
fluid changes, not to the resistance of aluminum to corrosion.

But my point is that Honda went out of their way to explain the phenomenon
of friction damage, so that's a known issue as well.

 

dude, with respect, the aluminum cylinder is most definitely part of the
reason. oh, and efforts of the chemists for the fluid.

ok, serious question: for /your/ master cylinder, knowing what you do
about its internal condition, what makes you argue for an old wives tale?

 

you should also be concerned about the condition of the brakes at all
4 wheels if routine maintenance was neglected for 10 years. however,
it is unlikely that you've gone 230K miles on the original brakes pads/
shoes. and it is also unlikely that when someone installed a new set
of pads/shoes they did not also flush the brake fluid. check your
receipts for brake work. odds are your brake fluid has been flushed
several times.

now I return you to the tegger/jim beam show already in progress...