my civic manual says every 30k to replace the fluid, is it really nessesary? I'm never had a vehicle very long to change it.
brake fluid really need to be changed?
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bleed and ounce or so from each wheel with every pad change and replace with fresh is all I've EVER done. If the car is pretty old you can remove a bit more and faster by draining the reservoir with a turkey-baster and refilling with fresh. Brake fluid does absorb water from the air and degrades over a long period of time.
I'm sure there are some of the, uhm, more "intense" who swear you should change it 100%every week and add some magic elixer and have it anal-yzed every year, however......
I'm sure there are some of the, uhm, more "intense" who swear you should change it 100%every week and add some magic elixer and have it anal-yzed every year, however......
If you do a search here, you will find extensive posts on the subject. In the past, nobody changed brake fluid. Now some manufacturers do recommend it. Ford and GM still insist it isn't needed. It may be necessary to keep Bosch ABS working. I tend towards ''If it ain't broke, don't fix it.'' Unnecessary messing around with the brake system can cause more problems that it solves. On the other hand, the rubber parts of the brake system do not last forever. The outer part of caliper pistons extends beyond the seals and is not wetted by the brake fluid. Changing the fluid does nothing to protect this vulnerable, failure prone component.
Most of the brake system is sealed with no way for moisture and dirt to enter. The weak points are the master cylinder and the calipers and wheel cylinders. Even with no maintenance, master cylinders last almost forever. I have never touched the one in my truck. It only has about 125K, but it is a 77. Most of the original brake fluid has been lost by preventive rebuilding of the calipers and wheel cylinders. I have also replaced all the brake hoses and the main line back to the rear brakes.
If you rebuild/replace the calipers or wheel cylinders at least every few lining changes and maybe replace the fluid in the master cylinder reservoir, I do not think additional changes of brake fluid are necessary. Still, I am not one to skip maintenance listed in my owners manual.
Most of the brake system is sealed with no way for moisture and dirt to enter. The weak points are the master cylinder and the calipers and wheel cylinders. Even with no maintenance, master cylinders last almost forever. I have never touched the one in my truck. It only has about 125K, but it is a 77. Most of the original brake fluid has been lost by preventive rebuilding of the calipers and wheel cylinders. I have also replaced all the brake hoses and the main line back to the rear brakes.
If you rebuild/replace the calipers or wheel cylinders at least every few lining changes and maybe replace the fluid in the master cylinder reservoir, I do not think additional changes of brake fluid are necessary. Still, I am not one to skip maintenance listed in my owners manual.
^
The point of changing it is so you don't have to replace/rebuild the wheel Cyl and Calipers.
The biggest reason they fail is BECAUSE people do not chnage their fluid enough. Heck spend $10 on a 1 man bleed kit and a bottle of fluid from autozone and be done with it.
I am a mechanic and change mine about once a year, and still have my factory calipers. The Wheel Cyl and front hoses had to be changed when I got the car, as the fluid was never changed before and it slugged up and wore them out.
Brake fluid = cheap. Repairing or having brakes fail = $$$
The point of changing it is so you don't have to replace/rebuild the wheel Cyl and Calipers.
The biggest reason they fail is BECAUSE people do not chnage their fluid enough. Heck spend $10 on a 1 man bleed kit and a bottle of fluid from autozone and be done with it.
I am a mechanic and change mine about once a year, and still have my factory calipers. The Wheel Cyl and front hoses had to be changed when I got the car, as the fluid was never changed before and it slugged up and wore them out.
Brake fluid = cheap. Repairing or having brakes fail = $$$
There is no such thing as a perfectly sealed system. On the brake system as the seals flex during normal operation a minute amount of atmosphere enters the hydraulic system and with the atmosphere a tiny amount of moisture from normal humidity. Heat from the brakes also degrades brake fluid, especially if it is already "wet".
Changing brake fluid ocassionally is good maintenance. I have seen my share of brake (and clutch) hydraulic systems that have failed from oid contaminated fluid.
How often to change? It helps to test the fluid if in doubt. There are test strips available that show how much moisture content there is in the fluid. From my experience, the longest I would want brake fluid in my car is three years.
Changing brake fluid ocassionally is good maintenance. I have seen my share of brake (and clutch) hydraulic systems that have failed from oid contaminated fluid.
How often to change? It helps to test the fluid if in doubt. There are test strips available that show how much moisture content there is in the fluid. From my experience, the longest I would want brake fluid in my car is three years.
--quote--
DOT 3 and DOT 4 brake fluids are ether based and, as such they are hygroscopic in nature - i.e. they adsorb water at every opportunity. Since water boils at 212 degrees Fahrenheit (100 degrees Celsius) the adsorbed water dramatically lowers the boiling point of the brake fluid. A minute amount of water suspended in the fluid decreases the boiling point as much as 1/3. **** ! The fluid in the system absorbs water through the breathers, through the caliper piston seals and by magic. Not only does this reduce the boiling point, the entrained water leads to corrosion of both ferrous and Aluminum internal parts. Double **** !! So buy your brake fluid in small containers and don’t save the leftovers.
--end quote--
http://www.stoptech.com/whitepapers/brakefluid1a.htm
(Pure water boils at 212°F only at atmospheric pressure. Under the pressure in a braking system the boiling point is higher. Moisture in a brake system absolutely does lower the point at which the brake fluid will flash to vapor under the heat of heavy braking.)
A friend was towing his horse trailer down Mt. Adams. Lots of downhill curves, and suddenly his brake pedal went to the floor. He got stopped with his parking brake and trailer brake, changed his shorts, looked for a problem and found nothing. A short time later, his brakes were OK. Old brake fluid which contained moisture had flashed to vapor from the heat of heavy braking. His mechanic checked the system, found nothing wrong except dark brake fluid, flushed and renewed the fluid, and everything is now OK.
Ken
DOT 3 and DOT 4 brake fluids are ether based and, as such they are hygroscopic in nature - i.e. they adsorb water at every opportunity. Since water boils at 212 degrees Fahrenheit (100 degrees Celsius) the adsorbed water dramatically lowers the boiling point of the brake fluid. A minute amount of water suspended in the fluid decreases the boiling point as much as 1/3. **** ! The fluid in the system absorbs water through the breathers, through the caliper piston seals and by magic. Not only does this reduce the boiling point, the entrained water leads to corrosion of both ferrous and Aluminum internal parts. Double **** !! So buy your brake fluid in small containers and don’t save the leftovers.
--end quote--
http://www.stoptech.com/whitepapers/brakefluid1a.htm
(Pure water boils at 212°F only at atmospheric pressure. Under the pressure in a braking system the boiling point is higher. Moisture in a brake system absolutely does lower the point at which the brake fluid will flash to vapor under the heat of heavy braking.)
A friend was towing his horse trailer down Mt. Adams. Lots of downhill curves, and suddenly his brake pedal went to the floor. He got stopped with his parking brake and trailer brake, changed his shorts, looked for a problem and found nothing. A short time later, his brakes were OK. Old brake fluid which contained moisture had flashed to vapor from the heat of heavy braking. His mechanic checked the system, found nothing wrong except dark brake fluid, flushed and renewed the fluid, and everything is now OK.
Ken
Not to mention that overtime as the fluid absorbs water, the braking efficiency is reduced. Your brakes could get spongier. Every two years is what I try to do. However, I've let cars go for 8 to 10 years with not much problem. But when you do flush and see the old brown stuff that comes out, then you'll have a different attitude toward changing it more often. I have replaced/refurbished wheel cylinders on my '55 Healey that were pretty well pitted, most likely from brake fluid that was left in way too long.
JHZR2
Staff member
My BMW says to do it every year, my MB every other year. Now some will say thats to get you into the service department. However, judging by how it looks in my chevy and my mother's plymouth after a couple years, I think theyre on the right tract to at least do it every other year. Its the most important safety item that you have after all!
Remember that having a car is a priveledge, not a right, and if you dont want to take care of it 100%, youre putting others in danger.
JMH
Remember that having a car is a priveledge, not a right, and if you dont want to take care of it 100%, youre putting others in danger.
JMH
A) Yes change it.
B) If any questions please refer to statement "A."
Actually I am sure you request a more thorogh answer than this
Brake Fluid is EXTREMELY hygroscopic, that is it has an affinity for picking up atmospheric H20!!
This contamination is inevitable!!!
Two serious outcomes, the safety is compromised as the brake fluid wet boiling point lowers out of specification.
Second, the presence of water in the brake components can cause accelerated corrosion.
A routine ABS Vacuum bleed can add life to pricey master cylinders, wheel cylinders, caliper seals, and reduce sludge build up.
BMW did a study a few years ago and they found within 2 years ABS fluid had a 3% H20 content.
That is clearly unacceptable to any self respecting car owner.
Best way is that have the system bled each time you get new pads etc, or every 2 years whichever comes 1st.
Just because other ignorant slackers ignore brake fluid does not mean you should.
If your brakes are being done INSIST they also flush the system.
Do not let them give you some old school "it is unnecessary" myth.
Think about how hostile an environment ABS lives in...absorbing H20, absorbing the unbelievable brake caliper temperatures etc.
Bearing this small sample of arguments, my only question to you in why not
B) If any questions please refer to statement "A."
Actually I am sure you request a more thorogh answer than this
Brake Fluid is EXTREMELY hygroscopic, that is it has an affinity for picking up atmospheric H20!!
This contamination is inevitable!!!
Two serious outcomes, the safety is compromised as the brake fluid wet boiling point lowers out of specification.
Second, the presence of water in the brake components can cause accelerated corrosion.
A routine ABS Vacuum bleed can add life to pricey master cylinders, wheel cylinders, caliper seals, and reduce sludge build up.
BMW did a study a few years ago and they found within 2 years ABS fluid had a 3% H20 content.
That is clearly unacceptable to any self respecting car owner.
Best way is that have the system bled each time you get new pads etc, or every 2 years whichever comes 1st.
Just because other ignorant slackers ignore brake fluid does not mean you should.
If your brakes are being done INSIST they also flush the system.
Do not let them give you some old school "it is unnecessary" myth.
Think about how hostile an environment ABS lives in...absorbing H20, absorbing the unbelievable brake caliper temperatures etc.
Bearing this small sample of arguments, my only question to you in why not
Nonsense! Calipers fail because the boots fail. Will somebody please explain to me how having new fluid inside the caliper, protects the boot on the outside? The real slackers are those that think changing the brake fluid will keep the the boots from getting old and fail to replace them and the seals in a timely manner.
The (maybe) original fluid in my Taurus didn't look so great compraed to the new stuff.
Change it.
Brakes are the most important part of your car.
Change it.
Brakes are the most important part of your car.
I knew as soon as i posted my response that they would be a plethora of fearmonger posts afterwards. I was not disappointed.
Boot seals can be cleaned and inspected externally quite easily and if so should last for a VERY long time. I don't think the original poster was quite there yet with only 30k miles.....
absorbed water in the brake fluid will NOT reduce braking capability in normal use (towing a loaded horse trailer thru the mountains is not normal use, especially for a CIVIC!). Water is a liquid and as such in incompressible, JUST LIKE BRAKE FLUID. The damage it causes will be corrosion of ferrous parts (which are actually fewer in newer designs) and that is the bulk of the issue with water in brake fluid. The resulting rust fleks can lodge in unfortunate places and cause some problems over time. Flushing typically gets rid of the oldest (and most used) fluid.
Yes, in extreme conditions it can cause other problems. However I doubt towing loaded horse trailers in in the offing for a Honda Civic....
Bleed them properly and don't lose sleep over it.
I wish people could just answer the question as asked and not get so anal about things.
Boot seals can be cleaned and inspected externally quite easily and if so should last for a VERY long time. I don't think the original poster was quite there yet with only 30k miles.....
absorbed water in the brake fluid will NOT reduce braking capability in normal use (towing a loaded horse trailer thru the mountains is not normal use, especially for a CIVIC!). Water is a liquid and as such in incompressible, JUST LIKE BRAKE FLUID. The damage it causes will be corrosion of ferrous parts (which are actually fewer in newer designs) and that is the bulk of the issue with water in brake fluid. The resulting rust fleks can lodge in unfortunate places and cause some problems over time. Flushing typically gets rid of the oldest (and most used) fluid.
Yes, in extreme conditions it can cause other problems. However I doubt towing loaded horse trailers in in the offing for a Honda Civic....
Bleed them properly and don't lose sleep over it.
I wish people could just answer the question as asked and not get so anal about things.
Kestas
Staff member
I'd say yes. And kudos for Chevrolet for having the guts to specify a fluid change interval for the brakes, unlike other manufacturers who don't care how the car fares after warranty. A dry climate certainly helps to reduce water levels in the fluid.
All discussion so far has been about water in brake fluid. Another issue to be worried about is dissolved copper in brake fluid. I posted a link to such an article in an earlier thread:
http://www.babcox.com/editorial/bf/bf50412.htm
I assume your Corvettes have ABS. It'd be a shame to skimp on a cheap maintenence procedure and have old brake fluid ruin your expensive ABS unit.
All discussion so far has been about water in brake fluid. Another issue to be worried about is dissolved copper in brake fluid. I posted a link to such an article in an earlier thread:
http://www.babcox.com/editorial/bf/bf50412.htm
I assume your Corvettes have ABS. It'd be a shame to skimp on a cheap maintenence procedure and have old brake fluid ruin your expensive ABS unit.
Labman,
I've had cast iron caliper piston bores honed because of the rust in them. No moisture, no rust, longer caliper life.
kenw,
Anybody can get their brakes really hot in emergency braking or steep, long downgrades (some have no idea about downshifting). Very hot brakes heat the brake fluid. Brake fluid containing moisture will flash to a vapor when very hot, even in a Civic, and your brake pedal goes to the floor.
A couple of years back a Dodge minivan was driving slowly down a very steep road in a nearby state park. He didn't know to downshift, his brakes got hot, the fluid vaporized, the minivan ran away, hit a kid, and the kid died. This analysis was well documented in the local newspapers during the trial.
Ken
I've had cast iron caliper piston bores honed because of the rust in them. No moisture, no rust, longer caliper life.
kenw,
Anybody can get their brakes really hot in emergency braking or steep, long downgrades (some have no idea about downshifting). Very hot brakes heat the brake fluid. Brake fluid containing moisture will flash to a vapor when very hot, even in a Civic, and your brake pedal goes to the floor.
A couple of years back a Dodge minivan was driving slowly down a very steep road in a nearby state park. He didn't know to downshift, his brakes got hot, the fluid vaporized, the minivan ran away, hit a kid, and the kid died. This analysis was well documented in the local newspapers during the trial.
Ken
The fluid must have been extremely high water content (ie, not properly bled, perhaps never?) to have enough % volume of water to cause the pedal to totally fail. Based on the limited info I have, I would call that an extreme case and not really valid for this discussion (nothing personal of course).
The fact is that proper bleeding will replace a large % of the old fluid, diluting any effect of moisture in the system. Eliminate it it? No, but it will reduce it below the point of reasonable concern.
Taking to to extremes we could demand that the brake fluid be changed under vaccuum to totally eliminate any moisture entrapment. And that seals be hermetic to prevent leakage.
Now, if we chose to live our lives based on extreme examples:
An off-course aircraft hit a light post in the fog near work today. Debris landed on several cars on the highway nearby. Therefore, I will never drive on any highway again.
My experience is, if you experience a mushy pedal under hard braking before you experience pad fade, then you need to flush your brake fluid. It's as simple as that.
When I was a kid, back in the mid 70's (The "good 'ole days!"), my Uncle taught me the importance of brake maintenance, including yearly fluid changes and flushing. He had an old Pontiac Wildcat with the original master cylinder, and that thing would stop on a dime. I like to change and flush/bleed my brakes once a year. It takes 30 minutes of my precious time (Horror! =8-0) and costs me around $6 in fluid (==8-0). I really like a solid brake pedal and reliable brakes. The only problem is I just took delivery of a new Toyota Prius and have no idea how I can flush/bleed the brakes, as they have Electric Assist.
These threads always attract a lot of nonsense. In years past very few people ever changed their brake fluid or had problems with brake fluid vaporizing. It does happen occasionally, but if it was due to merely the brake fluid getting old, it would be much more common. Old brake fluid is common, vaporizing isn't. Misused brakes usually fail by fading.
Calipers usually fail because the boots got old and failed, letting dirt and moisture in to degrade the piston and seal. Unless damaged, the boots should last 5-10 years or more. I have never had a caliper fail although I have never changed brake fluid and have let them go as long as 10 years before preventive rebuilding. In the real world, the boots pass some moisture and start to age the day they are installed. The older they get, the more of their elasticity they lose and the more they leak. They may eventually crack, and can be damaged any time. Nothing lasts forever. The boots are hard to inspect without taking the calipers off. Even if they still look good, you may not want to trust them until the new pads wear out. The piston seal keeps most of the dirt and moisture out of the caliper and the fluid. It is free to attack the outer part of the piston and what works in between the piston and seal, wears the seal. These areas are not wetted by the current brake fluid, and depend on the lube the caliper was originally assembled with. The piston moves very little, and mostly outward as the pads wear.
Depending on your driving, most people do not need to rebuild the calipers every pad change. I like to pull mine off every few changes and tear them apart and clean everything good. Fortunately I have always done so before the pistons were damaged. I slather everything down good with Sil Glyde before putting back together again with fresh rubber parts. That way I know the outer parts of the pistons don't have brake fluid or some equally hygroscopic brake grease on them to hold moisture and corrode them. Of course, rebuild/replacing the calipers loses a lot of brake fluid. Doing so every 5-10 years insures it is eventually replaced long before it goes bad. I am still waiting for an explanation of how changing the fluid inside the caliper can protect parts it doesn't even touch.
Calipers usually fail because the boots got old and failed, letting dirt and moisture in to degrade the piston and seal. Unless damaged, the boots should last 5-10 years or more. I have never had a caliper fail although I have never changed brake fluid and have let them go as long as 10 years before preventive rebuilding. In the real world, the boots pass some moisture and start to age the day they are installed. The older they get, the more of their elasticity they lose and the more they leak. They may eventually crack, and can be damaged any time. Nothing lasts forever. The boots are hard to inspect without taking the calipers off. Even if they still look good, you may not want to trust them until the new pads wear out. The piston seal keeps most of the dirt and moisture out of the caliper and the fluid. It is free to attack the outer part of the piston and what works in between the piston and seal, wears the seal. These areas are not wetted by the current brake fluid, and depend on the lube the caliper was originally assembled with. The piston moves very little, and mostly outward as the pads wear.
Depending on your driving, most people do not need to rebuild the calipers every pad change. I like to pull mine off every few changes and tear them apart and clean everything good. Fortunately I have always done so before the pistons were damaged. I slather everything down good with Sil Glyde before putting back together again with fresh rubber parts. That way I know the outer parts of the pistons don't have brake fluid or some equally hygroscopic brake grease on them to hold moisture and corrode them. Of course, rebuild/replacing the calipers loses a lot of brake fluid. Doing so every 5-10 years insures it is eventually replaced long before it goes bad. I am still waiting for an explanation of how changing the fluid inside the caliper can protect parts it doesn't even touch.
Kestas
Staff member
FYI, I have just learned on tonight's news that this plane was to carry former Pres. Bush Sr. on a trip today. All three crewmen died. Bush Sr. cancelled his trip.
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