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Discussion Starter · #1 · (Edited)
Someone I know was changing the brake pads on the rear, or front, I can't remember.

The brake pads were first replaced without bleeding anything, but the brakes felt spongy afterwards according to this person.
Looking back this may have been because of new pads on old rotors - because nothing had been bled at that point.

The bleeder valve on one or both of the calipers were then opened, and then the person went to the front of the car to press the brake pedal repeatedtly.
He went back after collecting a good amount of fluid and then closed the bleeder valve. But that's not the big issue here.

While doing this, the fluid reservoir went dry. How dry is hard to say, but it was empty.
After that, fluid bled from the bleeder valves was dumped back into the reservoir to fill it up.

Now the brakes are even more spongy than before - it takes three pumps of the brakes to feel somewhat firm while driving,
but then they go back to being really spongy after not using them again, and it takes 3 pumps to get them somewhat firm again, etc.




So the question now is what to do because there could be air that entered in the reservoir end of the system!

---Is it ok two get a two person system (one on the pedals, one near the bleeder valves) and bleed the system via
brake pumping and using bleeder valves the correct way (not allowing air into the system, while opening and closing the valves)?

---Would doing this drag the existing air that is in the reservoir side further into the system
to cause a huge problem with the innards of the brake system? (ABS, brake booster, other things)?

---What should be done? If there's air in the system on the reservoir end is it best to just have a mechanic bleed the system
using a pump, if that's even possible? Or is it worse than this - would the brake innards (ABS, brake booster, other things) have to be removed/replaced/repaired?




We don't know how bad this is and how to repair it - I've never dealt with air in from the fluid reservoir side and
I don't want any further damage to happen by trying to bleed air out through the bleeder valves using the brake pedal method.

Thanks for the help
 

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You could have damaged things, but before you panic, you need to do it right.

You might get answers that suggest bench bleeding the master... but I would start by trying to bleed it properly again. If you can't get it right, then you can move on to advanced topics like bench bleeding.

First, never put the fluid you bleed out back in the reservoir. It's got small air bubbles in it. In addition, it's most likely dirty because it's been in there a while. If also contains moisture since it's old - brake fluid absorbs moisture.

You need a proper flush and bleed. Here's what I'd do old school, but wait for more comments from others:

1. Fill the res
2. Get a short rubber hose (a foot or so) that will fit tightly on the bleeder valve. Put it on a bleeder. Put the hose in a glass jar with some brake fluid in the bottom so that the hose can't suck in air.
3. Put a 2x4 under the brake pedal so that it won't go to the floor.
4. Open the bleeder with the hose on it.
5. Have an assistant step on the pedal smoothly and so that fluid flows out. Watch the fluid flow into the jar. It will likely be full of air and look dirty.
6. You close the bleeder screw. Have the assistant slowly let up on the pedal.
7. Check the fluid level in the res. Repeat the steps 5 & 6 . Watch the fluid. You want it to come out clean and with no air bubbles.
8. Do step 7 again until it's clean and air-free.
9. Move to the other wheels and repeat the process.
10. After they are all done, go back and do each wheel one more time and make sure it's still clean and air-free.

Test and see how it feels. The brake pedal should not pump up at all. If it does, you still have air in there.

Note that you can short cut the process by using a pressure bleeder or a vacuum bleeder tool.
 

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You may want to suck some of the old fluid out of the reservoir first so it doesn't take as long for the new fluid to flush through.

In the future if you arent touching anything at the top of the system (master cylinder, ABS controller, etc) then you can just gravity bleed the calipers with no assistant necessary.
 

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Discussion Starter · #4 ·
Thanks for the info. It may be worth it to try another flush of the whole system to see what happens. Need to figure out from the other person just how much fluid was purged out, maybe he got lucky and it didn't bring air past the reservoir too far.

If air did get into the master cylinder, or ABS module, I'm wondering if a mechanic could do some kind of bleed/flush to get air out, but without removing any of these parts and doing a bench bleed. Or is a bench bleed completely necessary if this happens? Just trying to figure out what happens in this situation so a mechanic doesn't take advantage of the situation without us knowing what's going on.
 

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Two person works great, gravity works as well but a little slow, Motive is awesome, speed bleeders rock. Do a full bleed, drive car, let sit over night, if it's still funky when get into it in the am, re-bleed once again.
 

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Discussion Starter · #6 ·
Ok, also wondering - is there a certain order of calipers to bleed when doing a flush in a case like this?

Also, how much fluid capacity does the brake system need? Haven't done this stuff in a while and can't find it online..of course, my car over here has no manual either =P
 

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Discussion Starter · #7 ·
Flushed today by a mechanic, turns out the mechanic spotted the master cylinder leaking. So that may be the majority of the problem. Although it's possible air could have entered through the reservoir too. Master cylinder is being replaced and we'll see from there. Thanks again for the help
 

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Discussion Starter · #8 ·
Brakes are squishy still..But the word from the driver is no leak from the master cylinder after it was dried up, driven around, and then checked. So we're hesitant to hand the car over to have the master cylinder replaced just yet...

Could it be that the master cylinder needs to be bled, even after a flush by the mechanic was performed? Could there be air in it still?
Could it be that some other component needs air removed from it (but then again, if the mechanic flushed already, same question - would air in there even be possible...)?
Could it be that an inner component of the brake system actually just broke and is causing the squish?

So many unknowns..Will have to keep checking for leaks in the upcoming days and go from there before jumping to conclusions and replacing the master cylinder..would be terrible to do that and still have the same problem
 

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Discussion Starter · #9 ·
Turns out it was a caliper spring installed incorrectly. Now the brakes are fine. The leak in the master cyl isn't happening anymore, or never was. could have been just spilled fluid.
 
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