Does brake fluid go bad?

Lightman

Veteran Member
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Mar 10, 2002
Location
Sunny Florida
I just wondered if brake fluid must be disposed of after opening the can and doing a flush/fluid change? I know once it's exposed to air it can absorb moisture etc. I just bled the brakes with my new motive brake bleeder, and was wondering what I should do with the rest of the can of ATE blue? Thanks.
 

mrGutWrench

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Aug 29, 2002
Location
Wallace, NC
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'03 Jetta Wagon
LanduytG said: Well if you have away to draw a vacuum and seal it it would be fine.
Greg
__. What Greg is leaving (explicitly) unsaid is that brake fluid has a VERY strong chemical attraction for water from vapor in the air. It will extract the water molecules from the air and latch onto them and will not let them go until you pour the fluid into your brake system. Then, when the fluid gets hot, the water molecules are released - or actually transferred onto the metal components in your brake system. These molecules of water love to make little pitted corrosion spots and these spots seem to be heaviest where there's rubbing -- that's where the seals (rubber and similar materials) move on the metal parts. Quick end of story - rough metal wears out the seals, your brakes fail then (if you didn't total the car in an accident) your friendly local shop will charge you a couple C$$$ to replace the worn seals. Those 200$$ seals will last you about three weeks, then you get the pleasure of spending close to a thousand for new master cylinder or calipers ... assuming that you didn't total the car when the brakes went soft the second time.

__. You really don't want brake fluid in your car that's been exposed to air.
 

rotarykid

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1997 Passat TDI White,99.5 Blue Jetta TDI
Brake fluid = sponge . Water is easilly absorbed in the fluid . this is why it must be replaced every 2 years or so if you want a long brake life . The water will cause rust in metal parts throughout the brake system if not replaced regularly . Also the water in the system could make the system malfunction under heavy use if the water level is high enough .
 

Lightman

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Location
Sunny Florida
Ok thanks, so I'll toss it. How crazy do you have to be about closing the cap etc? I mean how long is too much air exposure? I tried to keep the cap open time to a minimum.
 

mrGutWrench

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Wallace, NC
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'03 Jetta Wagon
Lightman said:
Ok thanks, so I'll toss it. How crazy do you have to be about closing the cap etc? I mean how long is too much air exposure? I tried to keep the cap open time to a minimum.
__. Like most things in life, the real answer is "it depends". In a humid environment, pouring half the container out (and thus drawing in half a container's worth of wet air) is enough to put in a lot of water. And that stuff WILL pull every molecule of water out of the air -- even if you've sealed the cap. So, in some cases, the answer may be "just long enough to pour some out is too long". If you live in Phoenix, you may be OK - in Houston, you're gambling. So, whuddayathink -- ya feelin' lucky? For the price of a container of fluid versus how seldom we need fluid versus the damage that can be called, it's an easy decision for me.
 

tjl

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Mar 19, 2001
Location
California, USA
TDI
2001 Golf GLS
Lightman said:
I just wondered if brake fluid must be disposed of after opening the can and doing a flush/fluid change? I know once it's exposed to air it can absorb moisture etc.
Would it be safe to assume that an opened and then recapped container of brake fluid will absorb moisture at about the same rate as the brake fluid that is in the car's reservoir?

If so, then wouldn't it make sense to use the previously opened container of brake fluid only for topping off cars whose brake fluid was changed no more recently than the container of brake fluid was opened?
 

rwolff

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Mar 10, 2002
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Lesser continental mass, Tosev 3
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None yet
Another thing to watch out for: it's not just the brakes that need their fluid changed every 2 years. Some hydraulic clutches use brake fluid, and if it gets too old it damages the seals and starts leaking. Leak too much and there won't be enough left to disengage the clutch.

About a month ago, I had to get the clutch slave cylinder (10 year old gasser - still saving up for the TDI) replaced because of this.
 

mrGutWrench

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Joined
Aug 29, 2002
Location
Wallace, NC
TDI
'03 Jetta Wagon
[ QUOTE ]
tjl said: Would it be safe to assume that an opened and then recapped container of brake fluid will absorb moisture at about the same rate as the brake fluid that is in the car's reservoir?

[/ QUOTE ]

__. Well, no. The reservoir in your car is (supposed to be) sealed with a deformable gasket. As fluid is pumped to the wheel cylinders (calipers), the gasket should drop down with the fluid, thus keeping air away from the fluid. Of course, this will not be perfect but it's better than entire empty portion of a can. In real life, it works pretty well at keeping air/water vapor away from the fluid. It's also why your reservoir cap has all the warnings about cleaning the cap before you remove it, keeping the seal, and generally being careful with it.
 

Lightman

Veteran Member
Joined
Mar 10, 2002
Location
Sunny Florida
Well thats good. I ended up overfilling my reservoir the last time, so the fluid was up to the top, with NO air. When the level reduced if what you're saying is correct, must have had almost no air in there then.
 

ruking

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2003 VW Jetta, 5 M, Reflex Silver: 09 Jetta, 6 Sp DSG, Candy White: 12 VW Touareg, 8 Sp A/T, Flint Gray
[ QUOTE ]
DallasTDi said:
Please tell me you meant "dispose of correctly" instead of "toss it" in the trash....

[/ QUOTE ]

Here in Santa Clara County, As part of the water sewer refuse bill, non commerical disposal means making an appointment with the County Hazmat folks and bringing the marked container of brake fluid for disposal. The person who helps you is dressed in a full hazmat suit. Used motor oil is recycled curbside once a week, in approved one gal "milk type" plastic jugs. Mixing of different fluids is prohibited.
 
S

SkyPup

Guest
Yes, brake fluid does go bad real fast in contact with water.

You should dispose of your contaminated brake fluid by pouring it into your radiator fluid to increase the boil over point of your coolant and recycle the polyglycol..
 

rwolff

Veteran Member
Joined
Mar 10, 2002
Location
Lesser continental mass, Tosev 3
TDI
None yet
[ QUOTE ]

Hey Rob, are you coming to the 'gtg' next week?


[/ QUOTE ]

Didn't get a chance to log in until now (gotta stop buying books), and the "GTG" is probably well under way. I think I'll hold off until I'm out of the "future TDI owners" category.

BTW, want a good laugh? Check out www.trader.ca and do a search for Golfs with the keyword TDI (can't get a "portable" URL out of the search results). The oldest one listed is a 1993, and it's at a VW dealer. /images/graemlins/eek.gif You'd think they'd know that '93 Golf TDIs in Canada are about as common as '98 Passat TDIs.
 

sassyrel

Veteran Member
Joined
Mar 22, 2003
Location
aplington,iowa
TDI
passat,96,black-metalic
got some paint on the floor of garage from previous job--put used brake fluid on it--near instant lift off!! when mixed with used oil--recycler will refine it out--or is used in waste oil heater---burns great!!!
 

rotarykid

Top Post Dawg
Joined
Apr 27, 2003
Location
Piedmont of N.C. & the plains of Colorado
TDI
1997 Passat TDI White,99.5 Blue Jetta TDI
No TDI's in North America until the 1996 Passat & 1997 Jetta or Golf ???? /images/graemlins/grin.gif /images/graemlins/grin.gif /images/graemlins/grin.gif /images/graemlins/grin.gif /images/graemlins/grin.gif

On the other hand , January , February , March 1998 Passat TDI's were sold in the US .

Although I think that was the point of your post ??!/,.,.
 
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