Impossible to bleed brakes

[smdk2500]

No problem. Im sure it will be something simple and when you find it you will kick your self in the ass for not finding it. It seems like that is the way it happens easy fix that takes forever to find and ****** the hell out of you. Im sure some one else will chime in with some other suggestions as well.

 

[454cid]

I wonder if it's all the teflon tape you're using. Those fittings don't seal on the threads they seal at the double flare. If that tape is preventing the fittings from threading on all the way because its feels tight earlier, you're going to get a leak.

Also, I didn't see you mention this.... you replaced the hard lines, but with what? Prebent lines, or are you working with a roll of bulk tubing and flaring yourself? If a roll, what is it? Are you using double flares?

 

[Coroner81]

The teflon was only used the past week or so after I was running out of ideas trying to track down the issue. I only used a thin layer to minimize the chance of air being pulled in. I know with a proper flare/fitting it isn't needed. I'm just trying to narrow things down, try things I haven't done yet, etc..

Hard lines were replaced with straight steel lines from Advance auto, bent by hand, and double flares were used on all connections. There were no kinks during the bending process.

 

[east302]

I completely blocked off the rear brakes, and just ran with the fronts, and the brakes are decent.

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Where did you block it off? If it improves the pedal by removing the rear circuit, then (to me) that means that the problem is in the back.

I don’t remember without looking, but doesn’t the hard line split into two rubber lines at the axle? Maybe try moving the isolation point down, closer to the cylinders and see how the pedal responds.




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[454cid]

I don’t remember without looking, but doesn’t the hard line split into two rubber lines at the axle? Maybe try moving the isolation point down, closer to the cylinders and see how the pedal responds.

Mine only has one rubber hose in the rear..... there is no movement at the wheels independent from the rest of the axle so hard lines are used right to the wheel cylinders. That reminds me.... I have never replaced that rubber hose.

 

[Coroner81]

Where did you block it off? If it improves the pedal by removing the rear circuit, then (to me) that means that the problem is in the back.

I don’t remember without looking, but doesn’t the hard line split into two rubber lines at the axle? Maybe try moving the isolation point down, closer to the cylinders and see how the pedal responds.

I blocked the line coming out of the PV to the rear. I agree, I think the problem is somewhere in the back as well. The problem I'm having is being unable to find it lol.

I'm going to be checking the fittings on the line going to the rear tomorrow, I'll block them off at each section to test out each section.

Like 454 said, the high pressure hose runs from the body- where the hard steel line terminates, and is bolted onto a bracket that's mounted on a bolt on the diff cover. From that point it runs a line to each wheel cylinder.

I usually don't have problems with the brake hoses, but in chasing this problem, I ended up replacing them just to rule something out. The fronts were pretty ugly inside, I'm glad I replaced them. For $10-15 a pop, it's a cheap piece of mind.

 

[Coroner81]

Morning everyone. I figured I'd post a quick picture of the setup under the hood. Pardon the rust, this is a DD, and I'm in the land of winter and salt.

Obviously the MC on the left, brass PV on the right.
On the PV:
Top left is the rear input from MC
Top right is the front input from MC
Left of PV runs to the rear
Right out from PV runs to LF
Bottom out from PV runs to RF

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I removed everything from the PV that runs to the back. The couplings and hose are looking pretty scabby. I'm going to clean everything up, clean up all the flares, and throw it all back together

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[454cid]

Nice microwave plate... have you found a use for it in the garage?

 

[Coroner81]

Lol yeah, I use it when I'm cleaning things up with various oils and solvents. It keeps most of it off the bench.

I have the couplings cleaned, one is being replaced since I can't clean the sludge out. 2 out of 3 lines have been cleaned up, and reflared one end. I have 1 more line to check over, which needs a new flare on one end, then it's all going back together.

But right now, it's time for a coffee break. I'll update this when I'm done with bleeding, or if I run into another problem. Whichever comes first.

 

[Coroner81]

2 quarts through each rear wheel, and not a goddamn thing changed.

Fronts bled fine. If I can find enough F's to give, Ill try replacing the rear hose this weekend. It looks like it should be a little longer. (That's what she said) After that I quit.

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