well what this caused this and how can i fix it.. lata Dave

 

I don't have a good explanation for what causes it besides age, but all my RX's have had the same situation. Easy fix, just bleed all of the fluid out starting with the rear passenger side. Good time to replace the old DOT 3 with DOT 4.
just my opinion,
hanman

 

Water.. Brake fluid (which is what you use in the clutch as well) is hydroscopic, meaning that it absorbs water out of the air. This isn't as bad as it is in the brakes (since water dramatically lowers the brake fluid's boiling point, and your slave cylinder never gets that hot) but it can rust out the line over time. Good idea to flush that thing out soon... Follow shop manual instructions to do so.

PaulC

 

Not trying to flame silkworm but I believe the correct term is hyGroscopic instead of hydroscopic. My dictionary doesn't even show hydroscopic as a word. The other posts are correct though. DOT 3 fluid is the *****. It will absorb moisture out of the air even through the rubber hoses.

Check out the owner's manual on any vehicle that uses DOT 3. It will tell you to change the brake fluid every year ot two. The cars that use DOT 5 do not say this. The water and DOT 3 fluid interact to create a sludge and the two are extremely corrosive to metal parts in your brake or clutch system. Look at an old cylinder to see what I mean. It will be full of pits. DOT 5 is silicone based and does not absorb moisture.

Unfortunately I think DOT 5 fluid is not usually compatible with DOT 3 system seals. I don't believe you can simply put DOT 5 in a DOT 3 system. Besides, DOT 5 is asskicking expensive, running about 50 bucks a quart around here. Some Japanese cars and most all German cars use DOT 5 now. Most motorcycles use it as well.

The black color may be from the deteriorating seals too. You might consider a rebuild soon to avoid complete failure of your system. With age these seals will turn to jelly.

Try some Valvoline synthetic brake fluid. It is compatible with all other fluids and is not hygroscopic. It is available around here from Auto Zone and runs about seven bucks a quart. Do not simply replace the fluid in the reservoir. Bleed the entire system while you are at it until you get fresh fluid out of the bleed valve. A 25 dollar vacuum bleed kit is a good tool to have. It makes short work of this. The kit consists of a hand operated vacuum pump, a special jar to catch the fluid, and various adapters to fit on the bleed screws. The clutch system is very simple to do since it has only one bleed valve. Auto Zone will probably have this tool in stock. On the brakes, start at the bleed valve on the brake system that is the greatest distance from the master cylinder, (usually the right rear wheel) and progress to the next closest. etc. Simple with a vacuum bleed kit. Make sure the reservoir is full, crack open the bleed screw, and suck fluid out until it is clear. Make sure you keep the fluid level in the reservoir high enough at all times to prevent sucking air into the system.

Be sure to discard the fluid sucked into the jar even if it appears clean. Do not try to reuse it.

 

Picky picky

 

Watch out - there's some terms used very loosely in here on brake fluid specs...

http://fc3s-pro.com/TECH/MODS/BRAKES/bfluid.htm




-Ted

 

check ur clutch slave cylinder,mine fluid was the same color,when my slave popped the rubber internaly.the slave is on the back of the engine,if u d/c the hard line to it and pull it out,then take the slave off.the slave is held on by 2 10 or 12 mm bolts,when u have it off,pop off the rubber on top and check the rubber inside.Make sure it moves freely and isnt deteriorated.This MAY be ur problem,but I would check it anyway it only take 10-15 mins and can save a LOT of problems later on. good luck.

JUSTIN

 

mines is black already and i just changed the clutch master cylinder like a month ago.. but it turned black like in 4 or 5 days

 

somethings JUST do NOT mix with water

 

The problem with DOT 5 is just that, it does not mix with water. Instead, it has been proven that it form pockets of water in the brake (or whatever) system, and these pockets of water form rust VERY quickly. For a street car, it will be fine to use DOT 4 if you keep the cap on the system as much as possible, and ffush it every year. DOT five in a street car requires flushing just as regularly, if not more, and is much, much more expensive.
Try using Ford's heavy duty brake fluid. little more expensive, but good stuff.
For the black systems, try flushing the system with brake cleaner, and take a look at your seals, and then put in brand new fluid.
Sean Cathcart