Quote:
Originally Posted by work&play
What is the best way to change the brake fluid ?
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Here's how I do it and it's pretty simple:
1) First, I use a large turkey baster to suck all of the fluid out of the reservoir and into a container held right next to it. You want to be careful not to get brake fluid on any painted parts, I do this part completely under the hood. If you do spill any drips, dump some clean water on inner fender or where ever it drips. Water dissipates brake fluid.
2) Open one bleeder valve after another and GENTLY pump the pedal a little to clear most of the line. You could also just open the bleeder, put a piece of small hose on it and let gravity run its course but my way is quicker. You don't want to pump the heck out of the pedal or make it travel further than it usually does, this can destroy the seal in the master cylinder, especially on an older MC. (Ask how I know...).
2A) You can also hook a small vacuum pump to each bleeder and suck fluid out if you have one but a couple gentle pedal pumps works great and is quicker, IMO.
Now the system is fairly empty. It does not have to be completely empty at all, new fluid will pump the dirty stuff out fast when you get to the refill/bleed part.
3) This step is optional but if the old fluid has been in for years, the reservoir is usually really dirty. On some vehicles, you can buy a new brake fluid reservoir by itself, (w/o purchasing a master cylinder), if the old one is horrible and a new one is cheap, this would be a no-brainer. Usually they are either unavailable separately or expensive, however. It's always a judgement call. Sometimes the res is fairly clean. You can bet your ass that the dealer won't clean it out, they either replace it or simply pour new fluid right back in a dirty one. I've seen many w/ a real nice layer of sludge on the bottom, I won't have that in my system.
Soooo..., I usually clean the reservoir. They are always removable, most just pull straight up w/ a little persuasion. Our trucks have what looks like a pin or two clearly visible that needs to be removed in order to lift it off. (Haven't done this truck yet but I can see the pins).
Lift the reservoir off. Always have a small plastic drain pan next to MC and lift it right into that, it will always still have a little dirty fluid in it which will now drain freely out holes.
I rinse the reservoir out w/ real hot water, (usually boil a pan-full and then let it cool slightly), I also use soap and a clean small toilet brush or similar to scrub it out. Many reservoirs have chambers that you cannot get to w/ brush or fingers, you just have to pour soapy, hot water in and shake it a few times. I always figure that if I get 90% of the crap out on those I'm doing well. Plus you will definitely get anything remotely loose that will go straight into the new fluid.
Once you get it as clean as you can, rinse w/ distilled H2o or at least really clean water. If you have a bottle of Evian laying around, that'll work. I clean the screw-on cap and rubber seal at the same time as the res and rinse as well.
4)
Very important step: You need to dry the reservoir 100% before re-installing. You can blow some compressed air through it if you want for starters but it's usually not that helpful. You need to let it sit upside down on a clean piece of paper in the Arizona sun or the like for an hour while you do the rest of your brake job or whatever you're doing. If you don't live in the desert, a warm oven works great. I turn my oven on low for a while, then turn it off and set the res inside upside down on a piece of newspaper. If the oven is too hot to stick your hand inside for a couple seconds, you over-did this part and you are probably going to burn your house down and melt your resevoir. If you're not long on common sense and mechanical ability, you should not be working on brake systems, period. Pay attention to the part about turning oven OFF before putting res inside.
I'm a painter so I have heat-guns, (like a hair blow-dryer but a lot hotter). They work great for drying out resevoirs as well. You need to make sure that there is zero moisture in the res before putting it back on. Can't stress this enough.
Once you have your cleaned reservoir, or bought a new one , simply re-install it. The MC, (which should have been covered with a clean, lint-free rag this whole time), will still have some wet fluid on the rubber grommets where the res attaches and they usually pop right back in easily. Fill it w/ clean fluid.
There are a couple of accepted ways to bleed brake systems, I'm going to assume that if you're messing with the hydraulic part of your brakes, you know how to do it. While bleeding, the new fluid will quickly push out the old and you will be able to clearly see the new fluid coming out the bleeders, assuming there are no blockages in the system. The bleeding procedure is where you discover whether your lines are clear by the pressure of fluid expelled from bleeders. If any of the four wheel positions does not bleed well, investigate at this time and remedy. This is when you discover that you need new rubber lines. They can look OK on the outside but be nearly swollen shut on the inside if they are old.
If the difference is not clear between brand new fluid and what was already in your system, you did not need to do this procedure in the first place.
It took me longer to type this than it takes me to clean a reservoir but as FMTRVT correctly pointed out, brakes are no joke. I wrote this like a lawyer, (which I'm not), so as to cross all "t"s and dot all "i"s. Hope it helps.
