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Brakes won't bleed completely

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Mar 30, 2009, 7:53 AM

Post #1 of 3 (2218 views)
Brakes won't bleed completely Sign In

I have a 1998 3/4 ton dodge ram 4x4. The left caliper piston would not back out after applying brakes, i changed the caliper and put new pads on the front. Everything went back on easily but now i cant get all the air out. I have bled the brakes for 3 days, going through 2 large bottles of fluid. Started at the right rear, then left rear, then right front, then left front. Turn the truck off and back on and the pedal goes to the floor, pump it twice and its good, turn the truck off and back on and then it goes to the floor again. No fluid leakes anywhere.

Loren Champlain Sr
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Loren Champlain Sr profile image

Mar 30, 2009, 5:27 PM

Post #2 of 3 (2215 views)
Re: Brakes won't bleed completely Sign In

If you get a 'good' pedal after pumping a couple of times, there are two possibilities: 1) The rear brakes are out of adjustment, or 2) The primary cup of the master cylinder has taken a leave of absence. If it turns out to be the master cylinder, I'd recommend a new one vs. a reman. If you bench bleed the master well enough, you shouldn't have to go through the whole bleeding process again. But, check those rear brakes, first.
SW Washington

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DanD profile image

Apr 3, 2009, 10:17 AM

Post #3 of 3 (2193 views)
Re: Brakes won't bleed completely Sign In

Just a guess here but it might be an ABS issue?
Not to common but you may have inadvertently flushed some dirt into the ABS module (4 wheel anti lock) or into the hydraulic control unit, if this is a rear wheel only anti lock system. Both systems use one form or another of accumulator to store the released brake fluid pressure during an ABS event.
If something did get into either one of these unit’s “dump” valves the fluid might be leaking into the accumulator(s). After a couple of pumps of the peddle the accumulator fills and you get a normal feeling peddle. Release the peddle and the accumulator’s piston spring pushes the fluid back into the system; feels just like a bad master cylinder.
I’ve had it happen on a couple of rear wheel anti lock systems; One I was lucky and whatever was causing the internal leak flushed it self out. The other I had to replace the control unit; actually I by-passed it hydraulically; no more RWAL.


Canadian "EH"

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