Brake fluid flush

dennisdrive · Post by **dennisdrive** » Wed Jan 16, 2008 11:19 pm

Hello members,I had recently got the front brake serviced at the dealership and was advised to get the brake fluid flushed and replaced . The reason given was that during braking debris get collected in the fluid since it is being cycled and it needs to be changed.I wanted to know if that is necessary or one of the usual dealer tactics to fleece more money out of the owner.It is a 04 vibe with 46,000 km on it and has been on the road for 3 years to date .Thanks a bunch guys.

Sublimewind · Post by **Sublimewind** » Thu Jan 17, 2008 1:58 am

Not likely... I've seen debris in brake fluid, but nothing "I" would concern myself over... I'm not saying it shouldn't be flushed/changed, but i wouldn't pay the dealer to do it, but, I also do most of my service...

lovemyraffe · Post by **lovemyraffe** » Thu Jan 17, 2008 4:02 am

I've never heard of flushing brake fluid. I think it is a bunch of b.s. To me it just sounds like the $tealer trying to get more money. Flushing your tranny is just a ploy to get more money.

Sublimewind · Post by **Sublimewind** » Thu Jan 17, 2008 4:34 am

Quote, originally posted by lovemyraffe Â»I've never heard of flushing brake fluid. I think it is a bunch of b.s. To me it just sounds like the $tealer trying to get more money. Flushing your tranny is just a ploy to get more money. How long have you been alive mang??? Flushing brake fluid is a common practice, but not because of "debris" mainly due to breakdown caused by overheating and/or moisture infiltration (causing boiling) For 99% of the normal population, flushing isn't needed because most people don't flog the crap out of their brakes... but for people who do, or race/autocross, it's a COMMON thing..

NibCrom · Post by **NibCrom** » Thu Jan 17, 2008 4:52 am

It depends on how much he wants for it. Changing brake fluid is one of the easiest things you can do, all you probably need is a wrench, some tubing and new brake fluid. And doing it at all four corners would EASILY take less than an hour, including taking a break. If he wants to charge you any significant amount of money for it, just walk away, it's not worth it. I think I only change my brake fluid when I change brake pads, rotors or tires. Like Sublimewind said, most people don't have to worry about it, but if you autocross you will probably have to do it quite often.

Raven · Post by **Raven** » Thu Jan 17, 2008 5:16 am

Brake fluid is hygroscopic meaning it absorbs water from the humidity in the air. This water builds up gradually and eventually starts to cause corrosion in the braking system. If you're planning on keeping your car for a while, the fluid should be flushed every 2-3 years. It's a cheap preventitive measure which could save you hundreds of dollars in repairs later on.

Sublimewind · Post by **Sublimewind** » Thu Jan 17, 2008 5:25 am

Quote, originally posted by Raven Â»Brake fluid is hygroscopic meaning it absorbs water from the humidity in the air. This water builds up gradually and eventually starts to cause corrosion in the braking system. If you're planning on keeping your car for a while, the fluid should be flushed every 2-3 years. It's a cheap preventitive measure which could save you hundreds of dollars in repairs later on.Yep, it's hydroscopic IF it is an OPEN system or container, which the brake system is NOT... lol... If it were we'd be crashing into all sorts of stuff... the only portion that comes even close to being open is the reservoir. Being that the brake system is not a circulating system, only what is in the rez EVER comes close to being able to absorb water.... in a brake system when you push the pedal, you "might" get 25-30ml of fluid to move.... which gets pushed out and then, moves back into it's origional place when you release the pedal.

Raven · Post by **Raven** » Thu Jan 17, 2008 5:33 am

Then how does it get "moisture infiltration" as you stated above. Brake fluid will overheat and boil even without any moisture present under extreme conditions.

lovemyraffe · Post by **lovemyraffe** » Thu Jan 17, 2008 5:48 am

Quote, originally posted by Sublimewind Â» Flushing brake fluid is a common practice, but not because of "debris" mainly due to breakdown caused by overheating and/or moisture infiltration (causing boiling) For 99% of the normal population, flushing isn't needed because most people don't flog the crap out of their brakes... but for people who do, or race/autocross, it's a COMMON thing.. Ok so I might have been exaggerating a little when I said I've never heard of it. It can do some good. But like you said, 99% of the population will never need to "flush" their brakes. Living in a tranny shop, when the term "flush" comes up, I interpret it as pushing fluid through the tranny (or in this case the brake lines) and somehow that is supposed to magically fix everything. Flushing is pointless in most cases. To drain the system and refill it might be worth it though.

kevera · Post by **kevera** » Thu Jan 17, 2008 6:15 am

Glycols based fluid is hygroscopic and will absorb water from the atmosphere, reducing the boiling point of the fluid and degrading hydraulic efficiency. Changing fluid on a regular basis will greatly increase the performance of the brake system.DOT 4, DOT 3 and DOT 5.1, are a polyethylene glycol-based fluid (contrasted with DOT 5 which is silicone-based). Fluids such as DOT 4 are hygroscopic and will absorb water from the atmosphere. This degrades the fluid's performance by drastically reducing its boiling point. In a passenger car this is not much of an issue, but can be of serious concerns in racecars or motorcycles.

NibCrom · Post by **NibCrom** » Thu Jan 17, 2008 6:17 am

Yeah, you don't need too "flush" the system. Just get rid of the old fluid and replace it with new fluid. Some call it "bleeding brakes".

lovemyraffe · Post by **lovemyraffe** » Thu Jan 17, 2008 6:19 am

Bleeding makes more sense.

kevera · Post by **kevera** » Thu Jan 17, 2008 6:21 am

Actually "bleeding the brakes" is mostly used for removing air from the system.It can be used to remove most of the fluid though.

engineertwin2 · Post by **engineertwin2** » Thu Jan 17, 2008 6:44 am

Brake fluid is hygroscopic and one of the reasons you always replace the fluid instead of topping off. Sublimewind is right - it's a closed system. It's not perfect, but it minimizes the possibilities of absorbing water from the atmosphere later. That's also why you always crack open a new bottle and don't keep the last of a bottle for next time.Raven is right that brake fluid will boil even without any moisture present. Most of the overheating is heat bleed from the brake pads/drums themselves. Because the fluid is kept in a closed system, it is subject to "boiling" under vacuum pressure (also called cavitation). Most brake systems are designed to combat cavitation, but inevitably it will cavitate.As for flushing the brakes, well it should never cost more than an extra bottle or two of fluid, but they always seem to want more. The goal of flushing is to dilute any remaining contaminants as it's virtually impossible to remove all of them. If you left the cap off the brake fluid resevoir for a couple days it might be wise to flush, but it's never necessary.To me, some flushes do more harm than good (such as coolant flushes).

lovemyraffe · Post by **lovemyraffe** » Thu Jan 17, 2008 6:47 am

Quote, originally posted by engineertwin2 Â»To me, some flushes do more harm than good (such as coolant flushes).+1

dennisdrive · Post by **dennisdrive** » Thu Jan 17, 2008 6:58 am

Thanks a bunch guys , seems like i started a whole debate.Anyways , the dealer wants $110 for the job. I guess i will not get it done at the moment. However the brake fluid level in the reservoir is between Max. and Min. , should i top it up ? What is the recommended specification for Vibe? Is it Dot 3?

lovemyraffe · Post by **lovemyraffe** » Thu Jan 17, 2008 7:01 am

$110? That's insane!

kevera · Post by **kevera** » Thu Jan 17, 2008 7:17 am

Dot 3

dennisdrive · Post by **dennisdrive** » Thu Jan 17, 2008 7:21 am

I went thru the manula and it advises not to top up the fluid level , what do you think i should do ; leave it at the present level ( it is between Max. and Min. ) or TOP it ?

engineertwin2 · Post by **engineertwin2** » Thu Jan 17, 2008 7:29 am

Leave it at the level it's at now. It will expand a little when it's warm and be closer to the max line. So long as you are in between, it will be fine. OCD won't help out here.

joatmon · Post by **joatmon** » Thu Jan 17, 2008 8:42 am

Quote, originally posted by dennisdrive Â» it is between Max. and Min. I believe that the correct level is "between Min and Max", so yours sounds perfect.I have never flushed a brake system, and I wouldn't bother with the few kms your car has on it.If I ever did go to flush a brake system, I would do it by extensive bleeding of the brakes, using nice new clean brake fluid to push out the old, instead of emptying the brake system and then refilling and bleeding it.

Mavrik · Post by **Mavrik** » Thu Jan 17, 2008 8:48 am

I flush my brake system every 15,000 miles.

djb383 · Post by **djb383** » Thu Jan 17, 2008 10:41 am

....................and I've flushed the Dex-Cool out of both my GM vehicles. When just a little air mixes with Dex it turns into some nasty crud. A brake fluid flush/bleed is always a good idea and remember you start with the right rear, then left rear, then right front and last, driver front.

MadBill · Post by **MadBill** » Thu Jan 17, 2008 11:40 am

Years back, brake systems were not well sealed against moisture (and the drum brakes were great for boiling the fluid) and changing fluid regularly was an important safety consideration. Now we have rubber diaphragms isolating the fluid from humidity in the air , so corrosion and lowered boiling points due to moisture absorption are much less of an issue. (although water vapor can permeate through hoses, etc. in small quantities.)It's certainly cheap insurance to bleed the old fluid at the least when changing pads etc., and it also reduces the chances of having a seized bleed screw when/if you really need to bleed, but I find no reference in the owner's manual to doing so.BTW, as per the manual, the fluid should not normally be topped up in the absence of leakage as the level goes down as it flows into the brake piston cavities as pad wear occurs, and if topped up will overflow when the pistons are retracted to fit new pads.

Sublimewind · Post by **Sublimewind** » Thu Jan 17, 2008 10:42 pm

Quote, originally posted by NibCrom Â»Yeah, you don't need too "flush" the system. Just get rid of the old fluid and replace it with new fluid. Some call it "bleeding brakes".The terms are interchangable to a point... Bleeding is basically what Kavera said, mostly used to remove air, and a small quanity of fluid, THEN if you keep going with the proceedure and remove a LARGE quanity of fluid, you are flushing.... I know i've flushed my brakes and gotten well over a pint (~500ml) of BLACK fluid from the calipers, lines and rez.... It's cheap and easy to do... A good "better than stock" fluid is valvoline SynPower (IIRC) and it's in a Gold bottle... It still meets manufacture specs, it's compadible (many of the Silicone based ones ARE NOT) and it's synthetic and offers a higher boiling point and overall better performance..

Sublimewind · Post by **Sublimewind** » Thu Jan 17, 2008 10:45 pm

Quote, originally posted by dennisdrive Â»Thanks a bunch guys , seems like i started a whole debate.Anyways , the dealer wants $110 for the job. I guess i will not get it done at the moment. However the brake fluid level in the reservoir is between Max. and Min. , should i top it up ? What is the recommended specification for Vibe? Is it Dot 3?You've started a Mass-debation....!!!!!Not a bad thing man, it gets a lot of different minds and opinions to come out, which is a wonderfull learning tool... Some, may have knowledge that could possibly be incorrect, so if they post, and others see this, the knowledge base cn be corrected. I personaly LOVE this, because I don't claim to know everything and if someone can correct me, i'm VERY greatfull in being able to fix what I thought to have been correct...

Mavrik · Post by **Mavrik** » Fri Jan 18, 2008 1:17 am

you also have to keep in mind your climate. For example here in Alaska and this is from personal experience... I can get the brake fluid flushed out on someone's vehicle and its just black. Has 30,000 miles on it lets say. By the time it reaches 45k service, its black again. Because of the extreme cold here in alaska and I don't care how "sealed" the new brake systems are. The fluid breaks down rather quickly.Now in warmer states, probably not an issue. $110 is not a bad price. An hour of labor plus the brake fluid.You can never do to much preventative maintenance.

Sublimewind · Post by **Sublimewind** » Fri Jan 18, 2008 1:41 am

Quote, originally posted by Mavrik Â»you also have to keep in mind your climate. For example here in Alaska and this is from personal experience... I can get the brake fluid flushed out on someone's vehicle and its just black. Has 30,000 miles on it lets say. By the time it reaches 45k service, its black again. Because of the extreme cold here in alaska and I don't care how "sealed" the new brake systems are. The fluid breaks down rather quickly.Now in warmer states, probably not an issue. $110 is not a bad price. An hour of labor plus the brake fluid.You can never do to much preventative maintenance. Very well stated, and quoted for posterity

Brake fluid flush

Brake fluid flush

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