Brake fluid change (flush) - write-up

[kocho]

This has come-up a few times I'm sure, but here is my version... I decided to finally change the brake fluid on my 2000 Toyota Camry LE i4. It is at almost 120K/8 years so, according to some, it is six years overdue for this service

Next - power steering fluid and engine coolant, and I should be good for the next 120K miles

Well, to be honest, there is barely a perceptible difference in color b/w the used fluid and the new one. And really there is no difference in stopping ability before and after the service. So, IMO this was not really a necessary service but more a peace of mind type of thing... I would not recommend changing the fluid every 2 years at all - as I said, mine seemed perfect at 8 years! The old fluid had light amber color like light corn oil. The new is almost clear but still not fully transparent like water - it has a slight "warm" color cast. So much so that it was hard to tell when the clear fluid begins to come out the nipples. But I'm getting ahead of myself...

I followed someone's advice to just use a plain piece of clear tubbing, long enough to route up the wheel well (about 20" vertical up-direction, hang thru a coil on the spring and down to a large jar slightly above the nipple level. Used masking tape to hold the tube in place to the jar. The vertical up-part of the tube ensures that at no time there is any air near the brake bleed nipple.

Before losening any nipples, I first sucked out as much fluid as I could from the reservoir with a common kitchen thingy that is used to take sauce out - a plastic tube with a rubber baloon at the end. Then fill-up with new fluid (cover everything around with two layers of thick paper towel and be ready to remove it if you spill fluid on it).

Then, (with the car raised on stands front and ramps rear, wheels *not* removed as it was not needed), I attached the tube on the first nipple in the back. Losen the nipple 8mm bolt by 1/2 turn or so (do not do more than that or it may leak!). Indeed, as soon as I losened the nipple, about 1-2 inches of fluid squirts out into the tube and from there it only builds-up as I sit in the driver's seat and pump the pedal a dozen times in a row or more, till I begin to see the fluid coming up the tube out the wheel well and down into the jar. There is no chance of air being sucked back in as far as I can tell. To even further avoid this chance, one can use a "one man" bleed kit - it is a $10 device which is essentially a tube with a valve on one end - I had one but could not find it so I did not use it this time...

I followed the Rear-Right, Rear-Left, Front-Right, Front-Left sequence. Used almost two bottles for the two rear wheels (more than 50% of it for the first one) just to make sure it flows out clear - as I said, the color of the 8 year/120K miles old fluid was barely darker than the new one so it was not easy to tell when to stop... I used another bottle and then some for the two front wheels - they took less to start coming out clear.

I found that for my car I can pump the pedal probably two dozen times before the level in the reservoir drops too much, but to be safe I kept refilling every one dozen pumps or so. The engine was *not* running in this procedure for me if it were running the brake assist may have changed the amount of pumping needed so be careful how you do it.

Took a total of about 3 bottles of Toyota DOT 3 fluid which I had bought some time ago for this purpose but never really got to do this until yesterday. I think two bottles might have been enough but I wanted to make sure it all came out clear, so I used a little more. Took me alone about 1 hour or so to finish (and a few dozen paper towels - becareful as the fluid is supposed to be damaging to paint!).

[Unco]

stop the misinformation. brake fluid goes off.

please don't go recomending people to avoid changing their brake fluid at the recommended intervals.

brake fluid absorbs moisture. and depending on the conditions, after a few years, some cars' brake fluid just about turns into water.

water + heat = bubbles (it's what happens when fluids reach their boiling point) --> spongey pedal --> brake fade --> no brakes when you need them most.

you may not drive your vehicle hard, which is why you probably didn't notice any difference. but i would not be caught driving a car that hasn't had its brake fluid changed in 8 years down a mountain road around tight bends. i know i wouldn't get to the bottom alive.

[kocho]

Originally Posted by Unco

stop the misinformation. brake fluid goes off.

please don't go recomending people to avoid changing their brake fluid at the recommended intervals.

brake fluid absorbs moisture. and depending on the conditions, after a few years, some cars' brake fluid just about turns into water.

water + heat = bubbles (it's what happens when fluids reach their boiling point) --> spongey pedal --> brake fade --> no brakes when you need them most.

you may not drive your vehicle hard, which is why you probably didn't notice any difference. but i would not be caught driving a car that hasn't had its brake fluid changed in 8 years down a mountain road around tight bends. i know i wouldn't get to the bottom alive.

Well, can you quote the recommended interval for '00 Toyota Camry 4 cylinder? Per the owner's service manual please? If my memory serves me right, the Toyota maintenance schedule that comes with the 2000 year car *does not* recommend this service at all for the life of the car. The respective service schedule for the Lexus ES 300 does recommend it however, but that's not a Camry. So, please, do not go recommend *optional* service under the cover of *recommended* service.

I do feel better after doing it but I want to stress that there is really no reason to change the fluid unless there are symptoms for fluid or brake operation degradation as you describe pretty well.

As to your other point on driving style. I do drive (on occasion) my car more aggressively than the average Camry owner. So much so that the rear drum brake vibrations under heavy load that were present in *all* four cilinder camrys that I tried (four of them that to date from friends etc., plus my current Prius '02 that also has drum brakes in the rear) bothered me during hard stops downhill with the car fully loaded. For this reason alone, I ended-up replacing the drums with disks (you can look-up my post on this from the past). The vibrations have been long gone since then. I want to point out that these vibrations used to only come-up when the drums heat-up and are under stress enough - they do not show in "normal" driving or you would see a flood of complaints about this from many more people. And you probably know that the rear brakes take a smaller fraction of the braking force compared to the front, so if the rear are heating-up you can only imagine how the fronts feel

Anyway, I certainly am not the authority on this, just sharing my experience, as you do yours - just let be objective and refer to our sources of information. Guidelines might as well have changed since the printed manual came out and I would be willing to know if they have, based on reliable source of information (not a *word of mouth* type of thing).

[bigbird]

even though it may not be required, id always say change it at 100K intervals, just to CYA. when i changed the fluid in my new car it had never been changed in 170K miles. didnt notice a huge differance but it did feel better, maby that was just perception though.

[JayMax03]

its a good write-up but some pics would've been better.

[wiccanferret]

Originally Posted by Unco

stop the misinformation. brake fluid goes off.

please don't go recomending people to avoid changing their brake fluid at the recommended intervals.

brake fluid absorbs moisture. and depending on the conditions, after a few years, some cars' brake fluid just about turns into water.

water + heat = bubbles (it's what happens when fluids reach their boiling point) --> spongey pedal --> brake fade --> no brakes when you need them most.

you may not drive your vehicle hard, which is why you probably didn't notice any difference. but i would not be caught driving a car that hasn't had its brake fluid changed in 8 years down a mountain road around tight bends. i know i wouldn't get to the bottom alive.

Maybe YOU should stop spreading misinformation. There is no "recommended interval" as per Toyota.

Not to say it shouldn't be done, but brake fluid is pretty easy to diagnose by looking at it.

[Unco]

Originally Posted by wiccanferret

Maybe YOU should stop spreading misinformation. There is no "recommended interval" as per Toyota.

Not to say it shouldn't be done, but brake fluid is pretty easy to diagnose by looking at it.

i have an issue with people doing 'write-ups' dismissing the importance of such a critical component of a motor vehicle.

i don't need to go doing any research on it as i have already done my technical training long time ago. but if you feel the need to verify what i'm writing, feel free to do a google search. there will be a lot of results from highly reliable and reputable sources that state the obvious:

FACT is, brake fluid's boiling point reduces with time. how the hell are you going to determine this by looking at it?

i have no idea why toyota don't recommend to change the brake fluid, it's stupid. i personally wouldn't care whether it's classified as optional or recommended and i never made a reference to such.

when i mentioned 'recommended intervals' i was referring to general knowledge on brake fluids: 1 to 2 years. i was not referring to a specific page on the service manual. i don't need to look for it to know it needs to be changed.

sorry if my post sounds arrogant, but brake fluid replacement is a touchy subject for me as i know the consequences of neglecting it. i didn't think you'd go looking up the service manual after i mentioned the word 'recommended', i was using it in a different context. i hope you all know how to use google and i urge you not to take my word for it and do some research of your own, or better still, ask your mechanic

[greggf]

Originally Posted by Unco

FACT is, brake fluid's boiling point reduces with time. how the hell are you going to determine this by looking at it?

Just to clarify... chemically speaking, the components of brake fluid themselves do not change over time to any significant degree. The problem is that the glycols used in brake fluid are hygroscopic. That is, this chemical component facilitates the absorption of moisture when given the chance. The water thus absorbed alters the compressibility of the mixture, particularly under conditions of very high heat. In principle, a completely sealed brake system should not need to have the fluid changed - ever. In reality, the system is protected only by a snap-on cap and some moisture will inevitably be absorbed over time. The good news is that brake fluid is inexpensive and the procedure for changing it is relatively easy (if not a bit messy).

[Unco]

Originally Posted by greggf

Just to clarify... chemically speaking, the components of brake fluid themselves do not change over time to any significant degree. The problem is that the glycols used in brake fluid are hygroscopic. That is, this chemical component facilitates the absorption of moisture when given the chance. The water thus absorbed alters the compressibility of the mixture, particularly under conditions of very high heat.

thanks greggf, i covered that in my first reply in layman's terms.

[Novice_cardude]

A bit off topic, but I assume that the absorption of moisture is what causes the brake fluid to turn green and smell nasty. I've worked on several cars with this green fluid, most of them using DOT 3 fluid, and most of them over 10 years old.

Any time I do brake work on those cars, I flush as much of the old fluid out, regardless if the customer pays for it or not. I do this simply because if I do a brake job, i'm responsible for how the car performs for the life of the brake linings.

We have test strips that we can dip into the fluid and find out how much water is in it, but I never use them. Something about dipping a strip into a fluid that's supposed to be sealed has always bothered me.

Good write-up, and good debate. Your fluid might not have strictly needed changing, but the flush service is recommended because not every car on the road still has relatively unspoiled brake fluid after 8 years.

[kocho]

Sorry to have stirred the debate! Google search indeed turned-up about tons of "evidence" that goes both ways - change it or not change it, depending on who's talking. I did not come across objective analysis of the amount of reduciton of the boiling point over time in Toyota vehicles. But I did see some specific publications that advised against changing the fluid in Toyota Camry too often and that referred to the service schedule for this vehicle.

So pick your bet - my own experience seems to confirm the latter, but if someone else has the opposite - please share: I'd like to know the latest factual information. But it's got to be based on significant facts, not on "potential" problems... Of course, anything will deteriorate over time - can I argue with that? No. But is a 0.05 % increase in moisture content significant? Or does it need to go up to 5%? Or may be 35%? Who can tell? The issue with me is whether 2 years or 1 year or 10 years are enough to let enough change happen to matter in practice. Same with oil changes - 3K or 10K miles? Only oil analysis can tell, although there might be some obvious visual signs like sludge or burnt smell (too late if you see/smell that!). People who have done critical oil analysis time over time in controlled conditions have concluded that good oils in "normal" conditions work well in to the 10K interval and therefore the 3K or 5K interval is an overkill. I'd like to see similar study for the brake fluid to be convinced one way or another.

In the Camry, there is a contact patch of about the size of one US half dollar coin with the air at the top of the fill reservoir, when it is full. And there is probably less than 0.5 cubic inch of air in contact with that small surface area. The outside environment is sealed by a pretty snug rubber cap and the rest of the system is fully closed - nothing of significance comes in or out. So, how much moisture would there be in 0.5 cubic inch of air and would this affect the performance of the fluid enough to matter? We are not talking an open system here at all, that is why I found my fluid in almost perfect condition visually and have not noticed performance issues with it after 8 years 120K miles ...

Anyway, my main goal for the write-up was to describe how this procedure can be done for pretty much just the cost of the fluid + 1 hour time, by a single person. Only 8mm wrench, clear tubbing, rags/paper towels and an empty jar was needed, which most folks probably have lying around in their basements... YMMV about the condition of your fluids

As for photos, just turn the steering wheel all the way to one side and look at the nipple on top of the caliper on the inside of the brakes - there should be a small rubber cap covering the nipple and the nipple itself has a 8mm head - that is the one that needs to be losened-up a 1/2 turn or so (losening it more created a slow leak for me during the flush). The back wheels should look the same - I have disk brakes, so not sure about drums but I think they are similar as far as the nipple goes. The key idea is to route the tubbing up then down so that there is a stack of fluid above the nipple at all times and no air comes in contact with the nipple at any point in time as you pump the brakes. If you are worried - prime the tubbing: fill it up with fluid before you losen the nipple or use the "one man" kits that I mentioned that should be available in auto parts stores and which does not allow the fluid or air to go back - it is a one-directional valve. And make sure you do not run out of fluid in the reservoir!

I think I saw some photos of this already on this board when I was searching...

[wahed3001]

Originally Posted by kocho

Sorry to have stirred the debate! Google search indeed turned-up about tons of "evidence" that goes both ways - change it or not change it, depending on who's talking. I did not come across objective analysis of the amount of reduciton of the boiling point over time in Toyota vehicles. But I did see some specific publications that advised against changing the fluid in Toyota Camry too often and that referred to the service schedule for this vehicle.

So pick your bet - my own experience seems to confirm the latter, but if someone else has the opposite - please share: I'd like to know the latest factual information. But it's got to be based on significant facts, not on "potential" problems... Of course, anything will deteriorate over time - can I argue with that? No. But is a 0.05 % increase in moisture content significant? Or does it need to go up to 5%? Or may be 35%? Who can tell? The issue with me is whether 2 years or 1 year or 10 years are enough to let enough change happen to matter in practice. Same with oil changes - 3K or 10K miles? Only oil analysis can tell, although there might be some obvious visual signs like sludge or burnt smell (too late if you see/smell that!). People who have done critical oil analysis time over time in controlled conditions have concluded that good oils in "normal" conditions work well in to the 10K interval and therefore the 3K or 5K interval is an overkill. I'd like to see similar study for the brake fluid to be convinced one way or another.

In the Camry, there is a contact patch of about the size of one US half dollar coin with the air at the top of the fill reservoir, when it is full. And there is probably less than 0.5 cubic inch of air in contact with that small surface area. The outside environment is sealed by a pretty snug rubber cap and the rest of the system is fully closed - nothing of significance comes in or out. So, how much moisture would there be in 0.5 cubic inch of air and would this affect the performance of the fluid enough to matter? We are not talking an open system here at all, that is why I found my fluid in almost perfect condition visually and have not noticed performance issues with it after 8 years 120K miles ...

Anyway, my main goal for the write-up was to describe how this procedure can be done for pretty much just the cost of the fluid + 1 hour time, by a single person. Only 8mm wrench, clear tubbing, rags/paper towels and an empty jar was needed, which most folks probably have lying around in their basements... YMMV about the condition of your fluids

As for photos, just turn the steering wheel all the way to one side and look at the nipple on top of the caliper on the inside of the brakes - there should be a small rubber cap covering the nipple and the nipple itself has a 8mm head - that is the one that needs to be losened-up a 1/2 turn or so (losening it more created a slow leak for me during the flush). The back wheels should look the same - I have disk brakes, so not sure about drums but I think they are similar as far as the nipple goes. The key idea is to route the tubbing up then down so that there is a stack of fluid above the nipple at all times and no air comes in contact with the nipple at any point in time as you pump the brakes. If you are worried - prime the tubbing: fill it up with fluid before you losen the nipple or use the "one man" kits that I mentioned that should be available in auto parts stores and which does not allow the fluid or air to go back - it is a one-directional valve. And make sure you do not run out of fluid in the reservoir!

I think I saw some photos of this already on this board when I was searching...

Seven 'nipple' in one post, YAY!

[wahed3001]

What if you just drain and refill the reservoir? How much of the total fluid does it replace?

[Unco]

Originally Posted by wahed3001

What if you just drain and refill the reservoir? How much of the total fluid does it replace?

not much at all. there is a lot more fluid contained within the brake lines and calipers than what's in the reservoir.

[Black95Cam]

i just bleed my brake.. never had i "flush" my brake system.. unless you would considering bleeding is flushing...