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Truck has 75K miles and I just replaced my brake fluid from all you guy's urging. So now I feel like I am in bizarro world because I am replacing the brake fluid, which I never heard of, BEFORE I am replacing the brake pads. Weird... By the way it didn't seem to make any difference in brake feel at all. |
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Your brake system will thank you for it many miles down the road. Glycol based brake fluid absorbs moisture, even humidity from the air. Over time the moisture build up can lead to corrosion in the bores of the calipers causing the brake pistons to hang up. |
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i do this procedure routinely on my fleet annually and almost never have a brake problem. i flushed mine saturday and the stuff that came out was just about emerald green in color. maybe smokey or larry m can give more info on why it changes. you can bet on one thing though, brake fluid is waaayyy cheaper that abs pumps and calipers. 
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Another reason you chould change BF periodically is to keep boiling point high. IF the boiling point falls below the temp that the fluid reaches in the calipers, you can lose your brakes. The boiled fluid may create a gas/steam pocket in caliper that may be of 2 or more ounces in volume. This gas pocket will push the brake fluid back through the master cylinder into reservoir. One stroke of master cylinder is 1/2 to 3/4 ounce typically, so the gas pocket can't be re-compressed by pushing brake pedal. Repeated pumping may allow you to build presure once again but by the time you accomplish pumping it up again you are off the road or into whatever was in front of you. The boiling temp drops proportional to the absorption of moisture. |
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The darker the fluid is, the more moisture it has absorbed. "Emerald Green" though, that I've never seen before. BTW - anyone who regularly bleeds brakes, invest in one of these gizmos: http://www.motiveproducts.com/ Greatest thing ever. Fill with fluid, attach it to the master cylinder, and pressureize. All you have to do is go around to each bleed screw and crack it open until the fluid runs clean and free of bubbles. I did the brake fluid on the Honda in like 10 minutes with this thing. |
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i checked out those bleeders and they loook like they would work fine. i used my 10yr old daughter!  she did just fine too!  as to the color, i see a lot of used brake fluid that's greenish when it comes out and all we use here is the motorcraft fluid, part# PM-1. that's what went in my truck saturday. i wonder who makes it for ford? 
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Quote: Your truck is a 2000 model, you should have changed it approx 4 times already, I think you should change yearly, not by how many miles are on the clock. |
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Quote: Would somebody like to explain to me why this is such a hot maintenance item now but just a few years ago was unheard of? I have never changed BF on a vehicle before and never had a brake failure. I understand moisture collects in BF, but the heat generated by usage dissipates said moisture. This is why a vehicle that is parked will get rust in the wheel cylinders in a matter of months, but my last truck that was a daily driver went 225K miles over 11 years on the original fluid. Why are you all so sold on changing the fluid now? Why was this not an issue 5-10 years ago?  BTW my old fluid also had a green hue to it. |
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Quote: I suspect it's just an increase in general awareness. For me, it was my involvement in road racing that brought it to my attention. |
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Quote: Like an earlier post said, wait till you get enough water in the fluid that it steams in a panic stop. Then your pedal goes to the floor. Manufactures have done many years of research, the European company's have been recommending brake flushes for close to 20 years. So it's not new. Toyota last year released data that indicated the fluid should be replaced every year. Quote: Parts are being made out of different metals than 15-20 years ago. Wayne B |
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In europe and asia, the changing out of brake fluid has always been promoted. In the US, the manufacturers got away from this philosophy in conjunction with SAE for a number of reasons and beliefs. One issue was there were a number of incidences where people put the wrong fluid in the brake fluid reservoir with disastrous results. Brake fluid drops it's boiling point with water absorption as we all know, but it tends to level off, usually at the 3-4 years point, unless overly exposed. And manufacturers generally design and modify their brake systems to accommodate that level of contamination, or boiling point. So for many people life is good. Didn't hurt that when that philosophy took hold that the national speed limit was 55. The newer active ABS controllers tend to be made of corrosion resistant materials, so those parts are not effected. But it's still not a perfect world. For one, the lines and master cylinders still are iron or steel based, and have the ability to contaminate ABS and other moving parts with rust particles. The OE friction materials as part of the "system" go through the brake fluid boil acceptance testing. And some of those pads use an underlayer between the steelbacks and friction materials to prevent heat transfer back to the caliper piston and brake fluid residing the calipers. Some of the OE shims or insulators also assist with this, including protecting the caliper piston rubber boots. Now when people change out to another brake pad, their is no assurance that the pads have the same thermal conductivity resistance. So their may be more of an issue. Aftermarket rotors also may not have the same vane design, which in the OE arena, is altered to assist in the heat rejection of the rotors. (See Album). Note- machining a rotor down to minimum thickness does not affect this in any practical terms. And the other is the owner operating the vehicle at higher then spec'd GVW or higher speeds then "normal", which can under perfect storm situations get to higher then 4 year old fluid boiling point levels. So far there are no tests that I am aware of that currently take into account a situation of trailer brake failure in this soup. May be soon by NHTSA. So back to the beginning. Many people can go many years (more then 4) without ever having any issues. But a screwed ABS controller after the warranty period is pretty expensive. And if you are an aggressive driver, run the vehicle with some overload conditions, tow a weighty trailer, or are a person who uses best oil, filters or other products for your car, having good fluid in a brake system should be a natural. |
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I must say it really depends on the vehicle how often the fluid needs to be changed. My Honda Accord had the same fluid in it for a long time and when I changed it it was still perfectly clear. When I changed the fluid on my truck it was disgusting. Which reminds me, I should change it again. |
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I don't disagree with that. Catch me in another forum as my alter ego and my message would be different. Here, Ford SD's, 2 years. |
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Ok then...can somebody point me in the direction of some DIY instructions on how to accomplish this. Dave |
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i know u have to start with the farthest point away from the resivoire (dunno how to spell) |
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Quote: That's a "little secret"  , but as a hint can you say Brakes. Larry, keeper of the "little secrets" CLICK HERE
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larry, do you know why the fluid turns greenish over time? moisture getting in cause it?
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(From various web sites...) DOT 3 and DOT 4 have an affinity for moisture causing both the reduction of the boiling point and also rust and corrosion problems in the brake system. Dot 5 fluid can withstand very high temperatures and has no affinity to moisture. However, it is higher in price and it's air retention properties make it difficult to bleed air from the brake system. It cannot be used in cars equiped with ABS because of this. HSMO has the highest boiling point, and it does not contribute to rust or corrosion. HSMO can be idenified by it's green color. No other fluid can be used in cars equiped with this fluid. Brake fluid is hydroscopic (absorbs water). When fresh from the can, it can be considered "dry" with the higher boiling point. That's why racers and people doing driver's schools change the brake fluid just before events. Over time, brake fluid absorbs water lowering its boiling point to the "wet" level. For street cars, wet boiling point numbers are more important than dry because the fluid stays in for quite a while (one to two years). After a few months, with exposure to humid air, the brake fluid performance is probably closer to the wet than dry point. Here's some other brake fluid info I posted a while back... Brake Fluid Recommendations -------------------------------------------------------------------------------- Normal Driving - Castrol LMA (Low Moisture Absorption), DOT 4, 446F dry and 311F wet boiling points, about $5 per quart, changed every year or two. Driver's schools (brakes at very high temp) - ATE Super Blue, DOT 4 spec, 536F dry and 392F wet boiling points, about $11 per quart, changed before every driver's school if it's more than a month old. In my case, about three changes a year for five or six schools. Brake fluid needs to be changed for two reasons, maintenance and performance (it takes about a quart to flush the system). Maintenance - changing old brake fluid removes water from the brake system. Brake fluid is hydroscopic, it absorbs water. Old brake fluid must be flushed out or water absorbed by the fluid eventually causes internal rust on the disk calipers and pistons. Performance - changing old brake fluid helps high temperature operation because fresh (dry) brake fluid has a higher boiling point than older (wet) brake fluid. If brake fluid boils, compressible gas bubbles form, resulting in a very spongy brake pedal. DOT Brake Fluid Specs -------------------------------------------------------------------------------- DOT 3 DOT 4 DOT 5 ----- ----- ----- Dry Boiling Point 401F 446F 500F Wet Boiling Point 284F 311F 356F The DOT 3 and DOT 4 specifications are for glycol based (regular) brake fluid, while DOT 5 is for silicone. Silicone DOT 5 is not compatible with the ABS hydraulic control unit because it doesn't lubricate the ABS pump like glycol based fluid. Silicone is slightly more compressible than glycol fluid. It has a higher wet boiling point because it doesn't absorb moisture like glycol fluid. This lack of moisture absorption causes problems when water gets in the brake system. Instead of mixing with the brake fluid (so it can be flushed out easily), the moisture gets trapped at low points in the system and causes rust. Edited by Flywheel (11/04/04 03:30 PM) |
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i guess it turning green is just a reaction to the moisture content as motorcraft brake fliud is almost clear when new and it has a very light amber color that is easy to see as it has been coming in a white plastic bottle for a few years now. thanks for the info. good stuff...
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Did mine after 65K and three years...Should have done it sooner. I started with "Coke" color fluid and ended up with nice crystal clear fluid. Not much change in the brake pedal, but I feel better about the having a clean system. tginz |
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Replaced my brake fluid - feel like I'm in bizarro world
