Clogged brake lines?

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jcmeyer5

jcmeyer5

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Overview of the system. 4 wheel drum brakes, manual, with a new (rebuilt) master cylinder and new front lines. Rear lines look good, as does the rear feed line.

The boy and I went to bleed the brakes last night. Bench bled the master cylinder, then we started with the rear because that's how I was taught (furthest to closest), passenger side. I tried vacuum bleeding, but as much as I tried, I couldnt get anything out of the bleeder. Switched to driver rear, same story. Had the boy jump in and pedal it... nothing. Fluid level in the reservoir is not going down. Fronts bled out perfectly.

As a diagnostic move, I opened up the passenger side rear bleeder and put the vacuum pump on the driver side rear. The lines on the differential (after the split) cleared out with a problem. So I think I have the problem isolated to the feed lines between the prop valve and the junction. Problem is, I have never heard of a CLOGGED brake line before. Certainly not to the extent where NOTHING gets through. FYI the parking brake is not hooked up if it matters... dont think it should.

Anyone else experience this?
 
Maybe leave Master cover off and try vacuum bleed from rear bleeder valve. Or disconnect brake line in rear and jack front up a little so gravity may let it run down with cover off. No pumping. If you get fluid snap on cover and try pumping again.
 
Disconnect the rear flex line from the hard line going forward and check for fluid there.
No fluid? move up to the next line fitting and repeat.
Could be the distribution block as already mentioned.
 
start at the rear end, disconnect the hose that feeds the brake dist block on the rear housing. remove the lines from both wheel cylinders. blow out with air. then open line at prop valve and do the same from there to the rear end. resemble and try bleeding
 
bad brake hose to the rear is usually the culprit .

Although I replaced all my brakes on my truck the other night and we tried vacuum bleeding the rear brakes and got nothing. Manual bleed nothing. My son saw a drip from the front. I had a small pin hole from rust in the line for rear brakes coming from the master. When we started this job the brakes worked good just a bumping rotor. Thought I was doing the truck some good. All of a sudden no brakes. Could have happened towing some weight though. Just had a heavy road trip.

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Oldmanmopar said:
bad brake hose to the rear is usually the culprit .
Click to expand...
I agree. Brake hoses go bad from the inside out. This is where I'd start. Disconnect the hose from the hard line and see if you have pressure there when you step on the brakes.
 
jcmeyer5 said:
Overview of the system. 4 wheel drum brakes, manual, with a new (rebuilt) master cylinder and new front lines. Rear lines look good, as does the rear feed line.

The boy and I went to bleed the brakes last night. Bench bled the master cylinder, then we started with the rear because that's how I was taught (furthest to closest), passenger side. I tried vacuum bleeding, but as much as I tried, I couldnt get anything out of the bleeder. Switched to driver rear, same story. Had the boy jump in and pedal it... nothing. Fluid level in the reservoir is not going down. Fronts bled out perfectly.

As a diagnostic move, I opened up the passenger side rear bleeder and put the vacuum pump on the driver side rear. The lines on the differential (after the split) cleared out with a problem. So I think I have the problem isolated to the feed lines between the prop valve and the junction. Problem is, I have never heard of a CLOGGED brake line before. Certainly not to the extent where NOTHING gets through. FYI the parking brake is not hooked up if it matters... dont think it should.

Anyone else experience this?
Click to expand...
Fought mine for couple weeks till I found bad prop valve
 
Well I took the cap off the distribution block. The rod is free and centered. I also had a trickle of brake fluid come out.

I’m soaking the rear fitting right now. It’s either the soft line or the hard line.
 
I've seen flex hoses do that. I've also seen lines get pinched from floor Jack's. But are you sure you have pressure coming out of the master? I only ask because it is possible for a piston to "overextend" inside and block the passages. I had one do that to me and ended up cracking all 4 bleeders loose and stabbing the pedal one time real hard then closed off the bleeders, It worked! Something inside jostled back into place and all was good after that.
 
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Soft line and hard line were rusted together. Had to cut the hard line to get the soft line out. Ran the pedal down once the soft line was out, and got fluid. So it appears to be the soft line, which I have on order. There’s enough hardline to reflare it and reuse it.
 
I had a blocked hard line on my 64 between the distribution valve and the rear hose. I know for a fact that it can happen although un likely as noted. I also bought some new 3/16 steel line from the parts store, bent up a new line, and no fluid. Yup crud in a new line.
 
Rubber hose.
I had a rubber fuel line do the same. I put air thru it until I got to 80 psi and still blocked. Easy fix.
 
Not uncommon for an old soft line to fail on the inside . I had a front (non-mopar) car soft line act like a check valve up front. Thought I had a sticky caliper.
 
Soft lines with brackets wrapped around the hose,very common to create a pinch point. Hoses that act like a check valve are more common than you think.
 
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