Brake Fluid Flush.

[Alexlind123]

My brake pedal went to the floor today, on the last stop before my house. A pump of the pedal firmed it up on the driveway. After i parked, i opened the reservoir and looked at the fluid...i would post a picture but i wouldnt want to traumatize any small children or otherwise (think tomato soup with a little squirt of chocolate syrup). Needless to say, the system will be completely flushed before i drive the car again.

Is there anything i should look out for? Are the symptoms indicative of more serious underlying problems? Can i perform inspections to rule out what might have caused the brake fluid to become so bad?

[rob101]

if your able to pump it up it just sounds like you have a CRAPLOAD of air in the system, hopefully and by the sounds of the dirty fluid it just needs to be flushed. just make sure you get all of the dirty fluid out of there. got sticky brakes on my e28 and My father and I have to pull pistons out and do some cleaning, hopefully the crap in the brake system hasn't affected the pistons too much. but unfortunately all you can do is suck it and see. just try the least expensive fix first and work your way to the solution. i'd say you just need to change the brake fluid and bleed it good by the sounds of it;)

[joshua43214]

You need a master cylinder. This is the first warning that a failing master cylinder gives before total failure.

Ok, that being said, verify the proper operation of the calipers, sometimes a claiper will stick from not properly lubing the slides. when the pad wears down enough, the caliper will slide abrubtly into a new position, causing the brake pedal to fall to the floor.

But back to my first point, You description is indicates a bad master cylinder. Your car has given you fair warning, ignore it at your own risk.

[Alexlind123]

You need a master cylinder. This is the first warning that a failing master cylinder gives before total failure.

Ok, that being said, verify the proper operation of the calipers, sometimes a claiper will stick from not properly lubing the slides. when the pad wears down enough, the caliper will slide abrubtly into a new position, causing the brake pedal to fall to the floor.

But back to my first point, You description is indicates a bad master cylinder. Your car has given you fair warning, ignore it at your own risk.

The fluid is so bad tho...does a bad master cylinder cause the fluid to go bad?

[Blitzkrieg Bob]

bad fluid can lead to premature failure of the brake system.

Bad/failing parts can show up in the fluid as the debrie is suspended in the fluid.

If the pedal went to the floor you have more then a fluid issue, sounds more like master, leak, air, caliper or combo.

[Alexlind123]

yes, there is alot of air in the system. There must be water as well, because of the rust color. While those are problems in themselves, they had to have been caused by something.

[E34 530]

yes, there is alot of air in the system. There must be water as well, because of the rust color. While those are problems in themselves, they had to have been caused by something.

What type of fluid was in the tank originally?? Maybe you just had regular brake fluid which is a maroonish/red color 95% of the time and that's why the color looks so off.

[bfd]

If you need a new master cylinder, Ultimate Garage is closing out on all hydraulics:

http://www.ultimategarage.com/bmwhydraulicsale-1105.html

[Nick.Hay]

Whilst on this topic...

How exactly is a brake system flush performed??

A mate wants it done on his R32 GTR Skyline... Can you buy a special cleaning fluid to run thru the system to flush out crap, or is it just "Feed new fluid in, and bleed the calipers til it runs clean??

[joshua43214]

the master cylinder has 2 pistons in it, with a primary seal at the forward each. at rest, just forward of each seal is a hole that allows fluid to enter the chamber.This hole is called a compensating port. if the seal is bad, fluid will leak past it and be forced up the compensting port. this spray of fluid agitates the fluid and allows air bubble to form in the resavoir. continued aggitation will cause the fluid to take on a milky or sickly appearance. when the pedal is released, the pistons move back via spring pressure and the bubbly air is drawn into the chamber.

This is how air enters a brake system at the master cylinder. it is the only common cause of outside air entering the system. There are other causes, but they are uncommon.

Brake fluid absorbs moisture from the air. when you overheat the brakes, the water will boil inside the system causing it to cavitate. these air pockets then compress when you aply the brakes. this compression and loss of braking power is called fade. After the fluid cools down, the steam then condenses back into liquid and the brakes function normaly.

Moisture in the system will corrode the ferrouse parts of the system, the corrosion will then accelerate wear on the seals. The seals in the master cylinder are loaded against the cylinder, they will wear over time regardless of the care taken. Replacing the fluid will prolong the life of the hydrolics many times over.

[SRR2]

You have a worse problem than just the master cylinder. You have a situation with the ABS unit. They're notoriously difficult to flush, and now it's contaminated with old rotten brake fluid.

I think you're going to have to take this to the dealer, and yes, they're probably going to charge you a bundle for it. They use the MODIC to cycle the ABS while pumping new brake fluid through it. You can't do this yourself.

I think it would be very dangerous to cheap out on this. You don't know the condition of the ABS, except that it's been compromised. And I don't think it's worth taking the risk with a half-assed 'repair' with something as critical as brakes. I can tell you that I wouldn't want to ride in this car until the brake system is back to factory standards. It's not worth putting yourself, your family, your friends, and a lot of innocent bystanders at risk to use this without a proper repair.

[Blitzkrieg Bob]

grab the turkey baster and suck out what evers in the reservoir, so you start out nice and clean.

bleed the longest line first. right rear (US lefty drive) then work your way back to the master, check your level often so you don't run dry and wind up with air in the ABS.

[Blitzkrieg Bob]

technical writer in our presence

[Nick.Hay]

Thanks Bob... :)

[rob101]

bleed the longest line first. right rear (US lefty drive) then work your way back to the master, check your level often so you don't run dry and wind up with air in the ABS.
same for us RHD people, the master is in the same place (yay we get an linkage to go from right to left!)

[Alexlind123]

I bled with new Dot4 fluid untill they ran clean and clear and bubble free. I will post an update after i test drive it.

[Alexlind123]

I test drove it around the driveway. The pedal is far firmer than it has ever been. Less pedal travel, less effort required to brake, an overall far better feel. I think its fixed :)

Edit: I even tested the ABS...it works perfectly, as usual.

[joshua43214]

I test drove it around the driveway. The pedal is far firmer than it has ever been. Less pedal travel, less effort required to brake, an overall far better feel. I think its fixed :)

Edit: I even tested the ABS...it works perfectly, as usual.

As I said earlier, your car gave you fair warning, ignore it at your own peril.

[BillionPa]

check the fluid in a week. it will probably look a bit dirty.

do a full flush again then.

[rob101]

As I said earlier, your car gave you fair warning, ignore it at your own peril.
cue scary music.

[Alexlind123]

bump

[joshua43214]

bump

Why?

[Alexlind123]

Should i replace all the brake lines? What does this involve? Where do i get brake lines? Is the thing about the ABS really true?

[joshua43214]

Should i replace all the brake lines? What does this involve? Where do i get brake lines? Is the thing about the ABS really true?

I don't know why you would be thinking of brakelines. re-read the posts. you have suffered a mechanical failure of some kind. brake fluid does not magicaly change into a gas for no reason. No amount of bleeding and flushing will change that. You need to find out what that problem is. Eliminate sticky calipers, leaks, etc, if nothing is found bad, replace the master cylinder.

And yes, the thing about the ABS is true, you need the dealer tool to flush it. If the brakes are flushed on their proper schedule, you can get away with not flushing it at the service. But if it has been neglected, as in your case, it needs to be flushed.

[SRR2]

Naaaaaaah, I was just makin' it up about all those tiny pump parts, valves, springs, passages in the ABS unit. By ALL MEANS, just drive around with contamination and crud in it.

Just do it in Washington where no one in my family lives.

[Alexlind123]

I certainly hope that you dont take offense to someone trying to get a second or third opinion on something online. I would expect you to do the same with me.

[Javier]

lights up to remind you that two years went by and you need to replace the Break fluid and the cooling fluid.

If you fail to do so, being the brake fluid a water sucker, you will end up with corroded parts and gases inside the brake lines. It is impossible to know how severe the damage is now, but I wouldn't expect surprises if you dedicate your next two months to closely monitor and flush your break system.

Remember that opened break fluid cans should be discarded as they tend to caught water.

Javier