civic_driver

Hey all,

I'd like to know how to properly flush the brake fluid from the braking system. I know how to bleed the brakes to remove air bubbles from the system, I just want to know how to flush the old brake fluid and put new one in there. Do I need to bench bleed the master cylinder (the manual doesn't say anything about bench bleeding; it just says fill it with fluid and bleed it normally)? Also, if you have the chance, please provide a link to an article on how to do it properly.

The relevant info is in my siggy.

Thanks!

g230sport

at work when we do a brake flush, we either use the pressure bleeder which hooks up to the reservoir and pushes brake fluid through the lines. or we suck the old fluid out of the reservoir, fill with new, and bleed each wheel until the fluid is clean.

simple as that...

civic_driver

How do you suck the old fluid out? Do you use any special equipment?

The service manual says to use a syringe to remove the old fluid out of the master cylinder but I don't think that will work for removing the brake fluid from the brake lines.

If I pump the pedal and open the bleed screw at the calipers will I be able to take the old fluid out this way?

slvrlude

yes...what you can do is fill up a clear bottle/cup with new brake fluid about 1/4 of the way, hook up a line from your bleeder screw and put the other end of the line in the cup that you filled.....make sure to always keep the brake reservoir filled to at least the minimun level....have somebody pump the brake pedal and flush it that way.....always start with the farthest caliper though--rear passenger--and work your way closer in the to the reservoir. repeat as necessary...but the other methods work fine, and they are designed pretty much so one person alone can work on it

civic_driver

That's pretty much how you bleed them. I know this much. And in the service manual, for a 96-00 civics, the bleeding order is RR, FL, RL, FR.

I wouldn't want to mix old fluid with new if possible. I would like to remove the old fluid and put new in.

shogee

the cheapest and easiest way to flush your brakes at home is to crack all your bleeder screws until fluid drips out, then fill your master cylinder up with fresh fluid until clean fluid drips out. *remember to close the cover of the master cylinder after you fill it, brake fluid will absorb moisture and if left uncovered it will get ruined and defeat the purpose flushing the brakes. also i would do a bleed afterwards just to make sure no air is trapped. the whole process is called gravity bleeding

shogee

oh you dont need to bench bleed that's only if you take out the master cylinder to clean and rebuild or if you're replacing it

Jackal6042

Just bleed the brakes until new fluid is running to all four corners. I don't know why people are over complicating this. Bleed them RR, FL, RL, FR and you will be all good.

civic_driver

When I looked at the service manual for removing/installing the master cylinder it says it fill it with fluid and bleed it. It doesn't say anything about bench bleeding the master cylinder first and then installing it.

civic_driver

I'd like to hear more on this procedure.

I read that you can harm the master cylinder on older cars if you push the brake pedal all the way down while bleeding and the bleeder screw is unscrewed, on older cars; is this true for a 99 Honda? Can you really damage the master cylinder if you push the pedal all the way down while bleeding?

Marauder

Yes, you can damage the master cylinder by pushing the pedal all the way down.
Just think, when you normally use the brakes, you only push the pedal a small distance, cause of the pressure build up. They creates wear and can make a little step inside the cylinder. Then, if you push the pedal to the floor while bleeding, you will push the diaphragm over the edge that was created from daily wear and that can cut the seal on the diaphragm and cause you to need to replace the master cylinder.

A simple way to change the fluid, crack the RR bleed valve and pump out fluid until the reservoir is almost empty. Fill with new fluid, it helps if you use one of a different color. Then bleed each corner until the new color fluid comes out.

civic_driver

So how do you suggest I bleed it without damaging the master cylinder? I heard something about placing a wooden block below the brake pedal to keep the pushrod from going where it hasn't gone before.

The current fluid is pretty dirty so I can use regular fluid and still know when the old fluid is out. Thanks for the recommendation though.

thesmogman

Here is how I have done my cars.

Get rid of all the fluid in the master cyl.

Take a gatorade bottle or equivalent and put one hole in the top just big enough to get a vacuum hose in it. I use plastic airline tubing from a fish aquarium air pump.
Squeeze the bottle and put the hose into the master cyl's resevour and let go of the bottle. It will suck out the old fluid.

Fill the MC up with fresh fluid and bleed normally. Just bleed for a longer time. Bleed them til you see clear fluid coming out. Make sure you keep filling the MC.

You can use that bottle for when you bleed too, just put the hose on the nipple and put another hole in the bottle. This way you recover the old fluid rather than get it all over.

As for the sequence for your car I am not sure. Some Honda's are different.

civic_driver

Yeah, after doing some research that's basically what I was planning on doing. And I know the sequence from the service manual.

My only question left is, do you put anything underneath the brake pedal to keep it from going all the way in and if so what?

shogee

there is an installed brake pedal height adjustment even if you push the pedal all the way down and open a bleeder screw you won't knock the cup seal out of the master cylinder. that is if you haven't messed with it. it should be like an adjustable rod and it only lets the pedal travel so far so no you should need anything to block the pedal but if you're worried i guess dont press all the way down

g230sport

pretty much general rule ive been tought is to never go to the floor with the pedal. i always let it sink a little bit just to get a good stream out of the bleeder, but thats me.

ive done probably 300 cars like this in the last 6 months, not one come back.

csc67

Can I get to the bleeder screw by just jacking the car up or do I need to remove the entire wheel?

gwl

I usually remove the wheel and use a vacuum pump to bleed the brakes.

Virtualwebman

I guess after 213,000 mi its about time to flush out the old brake fluid.