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2005 gmc envoy_slt_xuv
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34 Posts
Discussion Starter #1
I have a motive power bleeder. I pump it up to 20 psi and open the bleeder. Fluid doesn't seem to come out any faster then a gravity bleed. Pressure in bleeder barely drops after 30 seconds of bleeding. I was expecting it to shoot out a lot faster

Do I need to do anything with the pedal to open the gates inside master cylinder? I was under the impression when brakes are not pressed fluid can flow from reservoir freely(otherwise gravity bleed wouldn't work.)

I was thinking about paying someone to do a flush.. Do they do anything special - ie high speed pump it around to get all the air out.
 

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2002 gmc envoy_sle
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12 Posts
Bleeder

The brakes lines are long and very small diameter so don't expect a high flow rate of fluid with 20 psi. Try bumping (open/close) the bleeder if you are trying to get air out of the system. Always bleed the longest brake line first, passenger rear. Getting the old brown fluid out is the main point of bleeding. Yes gas can accumulate if the fluid gets hot, but if you get the old discolored fluid out, you will most likely also get out any gas.
 

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2004 chevy trailblazer_ls
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77 Posts
I recently pressured bled my friend's jeep. Same slow drip happened. Took the bleeders all the way out and same thing. After a minute or so the flood gates opened up. Turned out the fluid was super old and dirty. And the fact it sat a few years didn't help.
 

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2003 chevy trailblazer_ltz
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105 Posts
Yup. Take the bleeder screws OUT and clean them. They plug with dirt (very common.)

The hole in the caliper that fluid flows out of may also be plugged with crap. Any restriction anywhere in the system will reduce fluid flow.

I cheat: AFTER cleaning the bleeder screw with a small drill bit turned by hand, I put the screw in the caliper, put a hose on the screw to direct the fluid...then with the pressure bleeder connected to the master cylinder, and the other bleeder screws closed, STOMP on the brake pedal to force the "clots" out. Repeat as needed for any wheel cylinder/caliper that won't flow properly.

If the hose pops off the bleeder screw, you'll have fluid squirting all over.

I tend to use ~15 psi on my pressure bleeder, fluid shoots out the bleeder screw when everything is working properly.
 
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