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Can't bleed brakes


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I put on new calipers, then attempted to bleed the brakes. After spending hours with my kid working the pedal, I still had spongy brakes. Starting at furthest brake and working forward.

 

Then I bought a Mityvac hand pump bleeder and tried with it. This time I started at the closest brake to the master cylinder and worked backwards. The instructions with the vacuum said to go this way, and I read somewhere that this is proper if your chasing an air bubble. I dunno.

 

Anyway, at the front left brake, I would create vacuum pressure, and open the bleed nipple. Some fluid would come out, but pressure drops immediately. I could get more fluid to come if I kept pumping the vacuum, but I don't think this is what you have to do.

 

Moving on to the front right, the pressure would hold, even with the nipple open, and fluid would flow continuously. This seems normal and good.

 

Back left I need a new nipple so I can't test it. Somehow I stripped it since yesterday.

 

Back right, same deal as front left, pressure would not hold.

 

The fluid reservoir stays full after a day of driving, and I don't see leaks anywhere. Could lines be bad? Master cylinder bad?

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It's common to put the calipers on the wrong wheels. There is no marking on which goes to which side. If they're on the wrong side (switched) the bleeders will be on the bottom of the caliper and will never bleed properly. Air bubbles go up and out, they won't go down.

 

I learned this the hard way so if that's the problem don't worry about it, just switch em'.

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It's common to put the calipers on the wrong wheels. There is no marking on which goes to which side. If they're on the wrong side (switched) the bleeders will be on the bottom of the caliper and will never bleed properly. Air bubbles go up and out, they won't go down.

I wondered the same thing. A Mighty-Vac will bleed even if the master cylinder is bad, because it doesn't rely on the master cylinder to move any fluid.

 

Hoses down, bleeders up.

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Anyway, at the front left brake, I would create vacuum pressure, and open the bleed nipple. Some fluid would come out, but pressure drops immediately. I could get more fluid to come if I kept pumping the vacuum, but I don't think this is what you have to do.

The pressure is supposed to drop immediately when you crack the bleed screw. Pump up, hold, crack the bleed screw while your helper is applying pressure to the brake pedal, brake pedal goes to the floor, tighten bleed screw before releasing the pedal. Repeat until all air is expelled. Put a clear hose on the bleed screw and immerse the other end in a clear jar so you can see the air coming out and the immersion will prevent air from being sucked back.

Moving on to the front right, the pressure would hold, even with the nipple open, and fluid would flow continuously. This seems normal and good.

If pressure holds with the bleed screw (nipple?) open, this is not good. It means the bleed screw is clogged. Clean it out or replace it.

 

Back left I need a new nipple so I can't test it. Somehow I stripped it since yesterday. Back right, same deal as front left, pressure would not hold.

Replace/unclog all the bleed screws, then start from scratch. Start with the RR wheel and work your way to the M/C.

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Thanks for the help. The bleed screws were up. I tried again, this time with teflon tape on each screw, and the pressure held well. Based on hornbrod's reply, I don't think he realized I was using a vacuum bleeder.

 

Its nice to have brakes again.

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Thanks for the help. The bleed screws were up. I tried again, this time with teflon tape on each screw, and the pressure held well. Based on hornbrod's reply, I don't think he realized I was using a vacuum bleeder.

 

Its nice to have brakes again.

 

Nope, I didn't. But happy you have brakes again. :clapping:

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