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#1 |
Registered User
Join Date: May 2013
Location: Central NC
Posts: 830
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Had to replace a brake line that I tried to move away from the exhaust. Tried to bleed brakes after line put in, unable to do it using the pump the pedal method.
Went and bought a vacum brake bleeder, did front in just a couple minutes, sucked out all the old stuff until nice new clean fluid came through. Tried to do the back, vacum pumps up to 25 inches on gauge, no fluid flows. Took rubber hose off thinking it could be clogged, fine. Hooked vacum to line, pulled new fluid from res. Put vacum back on bleeder valve on rear brake, same thing...25 inches of vacum, no fluid flow. Undid line into rear brake, old fluid drips out, vacum still wont pull through the brake even with line loose from back. Tried other side thinking cylinder went bad on this side, same thing. What am I doing wrong? Posted via Mobile Device
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1972 Cheyene C-10 "Ole Green" My Grandfathers truck (early 70's to 1983) My first vehicle (1983) Original 350 (3 rebuilds) 700R4 from Bowtie Overdrives ![]() |
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#2 |
Registered User
Join Date: Dec 1999
Location: Mid NE USA
Posts: 2,212
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Re: Why cant I bleed my rear brakes?
Are the shoes adjusted to the drum?
Ron
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#3 |
Active Member
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Location: Centrally located between Houston, Austin and Waco. BCS area.
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Re: Why cant I bleed my rear brakes?
Many years I had a similar problem.
With assistant's stepping on the brake I loosened the line at the master cylinder going to rear brakes to make sure fluid was coming out of there. I followed the brake line all the way back and any where there was a fitting I would loosen it up and again check to make sure fluid came out. When I loosened the rubber line above the rear axle, it oozed out. It was swollen inside. In your case, since you know that one is okay it may be the master cylinder piston or clogged somewhere else along the brake lines.
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68 GMC 250/3 speed Saginaw p/b p/s 69 Chevy 350/350 currently in pieces still lookin for a cab 06 Trailblazer I just want a vehicle that I can work on, that won't talk to me, leave error msgs or keep track of how I drive... |
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#4 | |
just can't cover up my redneck
Join Date: May 2004
Location: Columbus OH
Posts: 11,414
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Re: Why cant I bleed my rear brakes?
Disc front, drum rear?
Sounds like the proportioning valve is popped. It is a safety system that "cuts off" one end or the other if a leak develops. It "balances" between the front and rear until one end loses pressure. Bleeding the front first, especially with the problem in the rear, made it worse. You need to get it re-centered first, then the rear will bleed.
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#5 |
Registered User
Join Date: Feb 2006
Location: henderson ky
Posts: 196
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Re: Why cant I bleed my rear brakes?
assuming every thing was working fine before you replaced the line, here's what i would do.
always start at the wheel farthest from the master cylinder and work your way to it, in the order, right (passenger side) rear, left rear, right front, left front. tighten all bleeders and make sure the master cylinder is full. have some one push the brake pedal, don't pump it up and down, just push it to the floor, open bleeder, close bleeder. do that several times until all fluid and no air bubble come out. do this at each wheel. make sure you don't run out of fluid in the master cylinder or you'll have to start over. another thing you can do to get it started is gravity bleeding. take the cap off of the master cylinder and open all bleeders at once. watch until fluid starts coming out of each bleeder and then close them. this method can take a long time. |
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#6 |
Registered User
Join Date: Feb 2006
Location: henderson ky
Posts: 196
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Re: Why cant I bleed my rear brakes?
also, when using the vacume bleeder, take the cap off of the master cylinder. it'll never pull any fluid if the system is closed.
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#7 |
Registered User
Join Date: May 2013
Location: Central NC
Posts: 830
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Re: Why cant I bleed my rear brakes?
Thanks for the replies.
It is disc/drum. I can pull fluid to the line that goes to the backing plate with the vacum. Fluid nor air will move through the brake itself...did both wheel cylinders freeze up? Shouldn't I be able to at least pull air through them? I am at a loss...I am no mechanic, but a pretty good parts changer and this I have never run in to. Keep the ideas coming!!!!!!!
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1972 Cheyene C-10 "Ole Green" My Grandfathers truck (early 70's to 1983) My first vehicle (1983) Original 350 (3 rebuilds) 700R4 from Bowtie Overdrives ![]() Last edited by slow-1; 07-14-2013 at 09:05 PM. |
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#8 |
Registered User
Join Date: Dec 2012
Location: Providence, RI
Posts: 211
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Re: Why cant I bleed my rear brakes?
I had the same issue with my 71. The problem was the bleeder was clogged. Take the bleeder out and stick a small piece of wire into the hole the bleeder came out of, do the same to the bleeder itself. Once I did that, my vacuum pump pulled fluid quick
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#9 |
Registered User
Join Date: May 2013
Location: Central NC
Posts: 830
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Re: Why cant I bleed my rear brakes?
I assume they are...I drove the truck to where it sits, only change is the brake line.
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1972 Cheyene C-10 "Ole Green" My Grandfathers truck (early 70's to 1983) My first vehicle (1983) Original 350 (3 rebuilds) 700R4 from Bowtie Overdrives ![]() |
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#10 |
Registered User
Join Date: Jul 2010
Location: Willingboro, NJ
Posts: 489
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Re: Why cant I bleed my rear brakes?
If its both left and right wheel cylinders I would start cracking lines at the proportioning valve out put to rear brakes and then work backwards. Where ever fluid flow stops is your problem. A frozen wheel cylinder will only stop working, the little cylinders have nothing to do with flow thru the body of cylinder for bleeding purposes.
88Ironduke |
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#11 |
Registered User
Join Date: May 2013
Location: Central NC
Posts: 830
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Re: Why cant I bleed my rear brakes?
I took the bleeders out and they were open, but I did not probe the hole with a wire, I will try that next.
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1972 Cheyene C-10 "Ole Green" My Grandfathers truck (early 70's to 1983) My first vehicle (1983) Original 350 (3 rebuilds) 700R4 from Bowtie Overdrives ![]() |
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#12 | |
Registered User
Join Date: May 2013
Location: Central NC
Posts: 830
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Re: Why cant I bleed my rear brakes?
Quote:
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1972 Cheyene C-10 "Ole Green" My Grandfathers truck (early 70's to 1983) My first vehicle (1983) Original 350 (3 rebuilds) 700R4 from Bowtie Overdrives ![]() |
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#13 |
Special Order
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Location: Mt Airy, MD
Posts: 85,859
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Re: Why cant I bleed my rear brakes?
Sounds like proportioning valve issues,as others have said.
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#14 |
Registered User
Join Date: May 2010
Location: Hillsboro, Oregon 97123
Posts: 1,300
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Re: Why cant I bleed my rear brakes?
Replace the rubber hose in your brake line at the rear end..........it will look perfectly fine but it can be collapsed inside and you wont know it. I have had it happen many times.
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#15 |
Senior Member
Join Date: Nov 2003
Location: Brookings, SD
Posts: 10,497
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Re: Why cant I bleed my rear brakes?
I agree with the others check the proportioning valve.
Posted via Mobile Device Posted via Mobile Device
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#16 | |
"Ochre Ogre"
Join Date: Apr 2000
Location: Springfield, MN
Posts: 3,558
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Re: Why cant I bleed my rear brakes?
Quote:
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#17 |
Registered User
Join Date: May 2013
Location: Central NC
Posts: 830
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Re: Why cant I bleed my rear brakes?
Thanks for the continued replies!
I took the hose off, it is not clogged (gonna replace anyway while its off since its 40 years old). I can pull fluid with vacum easily up to the backing plate so I dont think its the prop valve. I'm hoping its the bleeding passage clogged, will check tonight. Posted via Mobile Device
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1972 Cheyene C-10 "Ole Green" My Grandfathers truck (early 70's to 1983) My first vehicle (1983) Original 350 (3 rebuilds) 700R4 from Bowtie Overdrives ![]() |
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#18 |
Registered User
Join Date: Sep 2011
Location: Wildrose, North Dakota
Posts: 300
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Re: Why cant I bleed my rear brakes?
I would rebuild the wheel cylinders while you have that stuff tore apart. If there is enough stuff in there to clog the bleeder I don't think it would hurt anything.
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#19 |
Proud owner of a 55.1 AD
![]() Join Date: Oct 2006
Location: Desert Hills, AZ
Posts: 460
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Re: Why cant I bleed my rear brakes?
Sounds like rebuilt/new wheel cylinders are in your future.
Rebuild them yourself for about $4 each or new for about $10 each. Posted via Mobile Device |
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#20 |
Senior Member
Join Date: Jan 2003
Location: daytonabeach
Posts: 22,956
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Re: Why cant I bleed my rear brakes?
sooo many threads about this.. doesnt anybody read a service manual ever?? the CORRECT procedure is in there in detail
clamp the pin on the combination valve
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#21 | |
Proud owner of a 55.1 AD
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Location: Desert Hills, AZ
Posts: 460
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Re: Why cant I bleed my rear brakes?
Quote:
Keep us posted on the resolution. I am interested. Posted via Mobile Device |
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#22 |
Registered User
Join Date: Feb 2012
Location: Mission Viejo, CA
Posts: 1,856
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Re: Why cant I bleed my rear brakes?
wheel cylinders are what $40? get new ones and be done with it.
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#23 | |
just can't cover up my redneck
Join Date: May 2004
Location: Columbus OH
Posts: 11,414
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Re: Why cant I bleed my rear brakes?
40 bucks? Heck no, calipers don't even cost that much. Wheel cylinders are less than 10$.
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You can review the site's rules here. Quote:
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#24 | |
Registered User
Join Date: May 2013
Location: Central NC
Posts: 830
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Re: Why cant I bleed my rear brakes?
Quote:
Took out the bleeders, poked a small zip tie into the hole it came out of, old fluid started dripping out. There was a gel like substance on the ziptie when I removed it, I guess it is congealed brake fluid. Put it all back together and was able to pull nice clean fluid from the MC through the bleeder with the vacuum. I haven't finished re-bleeding everything so not done yet, but on the right track. Thanks for all the help.
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1972 Cheyene C-10 "Ole Green" My Grandfathers truck (early 70's to 1983) My first vehicle (1983) Original 350 (3 rebuilds) 700R4 from Bowtie Overdrives ![]() |
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#25 | |
Registered User
Join Date: May 2013
Location: Central NC
Posts: 830
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Re: Why cant I bleed my rear brakes?
Quote:
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1972 Cheyene C-10 "Ole Green" My Grandfathers truck (early 70's to 1983) My first vehicle (1983) Original 350 (3 rebuilds) 700R4 from Bowtie Overdrives ![]() |
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