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-   -   Problem with flushing the brake system 03 Focus ZX5 (http://www.focusfanatics.com/forum/showthread.php?t=305306)

marsdog 12-30-2012 12:28 PM

Problem with flushing the brake system 03 Focus ZX5
 
Sorry, wrong place. Moved to general tech discussion

marsdog 12-30-2012 12:43 PM

Problem with flushing the brake system 03 Focus ZX5
 
I tried to flush the brake system of my 03 Focus ZX5. It has 80k miles and the mechanics warned me to change the brake fluid several times already.

I did the 'press pedal - open bleed screw - close bleed screw - release pedal' approach with a friend helping me and ran almost 1 qt new fluid through to get clear fluid come out of all four wheels.

Then the problem came -- I almost lost the brake force. I figured it must be some air went into the system during the process so I did the bleeding one more time. I didn't see much bubble (if any) come out during the bleeding. The brake pedal is quite firm with engine off but becomes very soft as soon as I turned the engine. Now I have some brake force but it is still softer than before.

Shall I bleed the system one more time? Does driving some miles help move air down the pipe? Is it possible I broke something else?

BTW: with the two-men approach, I don't have to leave some fluid in the waste fluid bottle, put the other end of bleed tube under the fluid and hold the bottle higher than bleed nipple, do I?

elsolo 12-30-2012 02:13 PM

How likely is it that you sucked a little air into the system by letting the fluid level in the master cylinder reservoir get too low?

If you have anti-lock brakes, you are supposed to disconnect the battery first. Not sure why or if it matters at all, I have never disconnected the battery to bleed the brakes on anything.

misfire 12-30-2012 02:49 PM

Quote:

Originally Posted by marsdog (Post 4518104)
Sorry, wrong place. Moved to general tech discussion

you didn't move it, you opened a new thread.

MERGED TO: Technical Chat thread already in existence.

whynotthinkwhynot 12-30-2012 03:31 PM

Eh, you don't need buddies. That process is slower, and more prone to issues afterwards. Get you a Miti-Vac brake bleeder kit for about $25. Some stores might let you rent it. This is a vacuum bleeder. Read the directions. Go bleed your brakes. You'll be done in less than an hour by yourself. Most of that time will be getting proper access to the bleeder nipple.

Now you did have the cap off the master cylinder when you were bleeding- right? If not, you will need a new master cylinder.

coldbear 12-30-2012 03:32 PM

Need a power bleed.
 
If you were bleeding brakes and now you have a soft pedal, you need to POWER BLEED that system. Since the introduction of ABS brakes, this system requires another bleeding process.( Power). You've probably got a small air pocket in your lines causing problems. Good luck, keep us informed how it came out.?

marsdog 12-30-2012 05:05 PM

There was once the fluid level in master cylinder reservoir lower than MIN. s
Maybe this caused the problem?

I don't have ABS so the old school way should work fine.


Quote:

Originally Posted by ello (Post 4518206)
How likely is it that you sucked a little air into the system by letting the fluid level in the master cylinder reservoir get too low?

If you have anti-lock brakes, you are supposed to disconnect the battery first. Not sure why or if it matters at all, I have never disconnected the battery to bleed the brakes on anything.


marsdog 12-30-2012 05:14 PM

Quote:

Originally Posted by whynotthinkwhynot (Post 4518293)
Eh, you don't need buddies. That process is slower, and more prone to issues afterwards. Get you a Miti-Vac brake bleeder kit for about $25. Some stores might let you rent it. This is a vacuum bleeder. Read the directions. Go bleed your brakes. You'll be done in less than an hour by yourself. Most of that time will be getting proper access to the bleeder nipple.

Now you did have the cap off the master cylinder when you were bleeding- right? If not, you will need a new master cylinder.

You mean leave the master cylinder reservoir open during bleeding? No, I did put the cap back (to avoid squirting fluid, I read somewhere) but disconnected the cable goes into the cap (not sure what that is for). How did this hurt the master cylinder?

whynotthinkwhynot 12-30-2012 05:24 PM

Quote:

Originally Posted by marsdog (Post 4518410)
You mean leave the master cylinder reservoir open during bleeding? No, I did put the cap back (to avoid squirting fluid, I read somewhere) but disconnected the cable goes into the cap (not sure what that is for). How did this hurt the master cylinder?

Brake fluid does not compress. So if you put the cap back on, then you have someone open up a bleeder, push fluid out, tighten the bleeder, and then let up on the pedal, things can break. AFAIK, there is not a design that overcomes this basic principle, but you might get lucky and it's just air in the system. A vacuum bleeder will set you straight. If you can get a hard pedal again- then you're ok. If not then you need to replace the master cylinder and be sure to follow the bench bleeding process, then vacuum bleed again.

marsdog 12-30-2012 05:31 PM

Quote:

Originally Posted by whynotthinkwhynot (Post 4518425)
Brake fluid does not compress. So if you put the cap back on, then you have someone open up a bleeder, push fluid out, tighten the bleeder, and then let up on the pedal, things can break. AFAIK, there is not a design that overcomes this basic principle, but you might get lucky and it's just air in the system. A vacuum bleeder will set you straight. If you can get a hard pedal again- then you're ok. If not then you need to replace the master cylinder and be sure to follow the bench bleeding process, then vacuum bleed again.

Thanks. Will try the vacuum bleeder. "Mity Vac MV8020 Brake Bleeding Kit" is what you referred to, right?

I drove 30+ miles with the soft pedal this afternoon and it was not that bad. Any other sign I can tell if the master cylinder is broken, e.g. fluid leak after driving?


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