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Post by mongoose on Aug 15, 2011 7:26:35 GMT -5
The next logical think to check is loosen the steel line at the rear rubber hose to see if you have flow there. It will if nothing else eliminate the rear rubber hose. I was doing an 87 Monte SS Dana 60 conversion two weeks ago and a brand new out the box Wagner line was plugged solid. But the sympton was a super high pedal with no rear brakes. The fix was taking the line off and having a bud at the local hydraulic supply house build me one out of 6200 psi braided Russel line. That was one of the things I did yesterday, since some of the new stuff I had put on (that I thought could not be working correctly) was the rear brake hose, new stainless lines, and new wheel cylinders. The flow out of the hard line where it attaches to the rear brake hose was pitiful.
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Post by mongoose on Aug 15, 2011 7:27:48 GMT -5
Just another thing to check. If you are wondering if the valve is stuck open, check the pin that turns out. Grab an ohm meter and set it to 1000 ohms. If the pin is connected to ground, it is stuck wide open and generally wont allow fluid flow to the rear port. I thought I could check the sensor to see if that could tell me anything... but I didn't know how to test it. Thanks for the tip... I'll go check it out.
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Post by mongoose on Aug 15, 2011 9:38:23 GMT -5
Tested grounding of the sensor... looks like that's a "Yes". My ohm meter doesn't have a 1000 ohm setting, but I tested with both a 2000 and a 200 ohm setting, and both tested positive for the sensor grounding from both the frame and the negative battery post. BTW... don't really know what the different settings 200 v. 2000 ohm settings do... except I thought it just changed the scale of the reading. Maybe someday I read something about that.
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Post by stan65cutlass on Aug 15, 2011 9:41:39 GMT -5
have you cracked a line at both ends of the prop valve? some times they wont center if fluids holding it back. my dad showed me that once, couldnt get the brake lite to go out after doing a brake job, it whent out as soon as he cracked it
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Deleted
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Post by Deleted on Aug 15, 2011 10:30:54 GMT -5
My guess would be that at one time the donor car lost a line or a wheel cylinder setting the prop valve to full front brakes and got stuck. Alot of time you can just violently jab the pedal if there is pressure to be had and it might reset. Just a PIA part in a PIA spot to have to change out twice.
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Post by mongoose on Aug 15, 2011 12:11:13 GMT -5
have you cracked a line at both ends of the prop valve? some times they wont center if fluids holding it back. my dad showed me that once, couldnt get the brake lite to go out after doing a brake job, it whent out as soon as he cracked it Are you saying I should open up both a front and rear bleeder screw, and then pump the brakes?
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Post by mongoose on Aug 15, 2011 12:23:41 GMT -5
My guess would be that at one time the donor car lost a line or a wheel cylinder setting the prop valve to full front brakes and got stuck. Alot of time you can just violently jab the pedal if there is pressure to be had and it might reset. Just a PIA part in a PIA spot to have to change out twice. I've used this prop valve since 1986, but during this last rebuild, the valve was open (meaning no master cylinder to valve brake lines were attached) for maybe a year. Car hasn't been outside during that period, but I'm guessing that the internals have rusted up, and as we've worked to bleed the system after installing new components, the piston moved around and got stuck. I've tapped (with a bit of force) on the "reset button" on the front of the valve, and I get a slight bit of movement from the button. When the brake pedal is pressed, I feel the button move forward slightly as pressure is applied, and it goes back when pressure is released. Not sure how much it's supposed to move, but it's maybe 1/8". I also stomped the brake pedal a few times, didn't seem to change things. I presume that the valve is stuck back in the cylinder, which would prevent the fluid from travelling to the rear brakes, which is why I can only pump fluid out of the front bleeders. Looks like there is enough evidence that the valve is toast, and that I should seek a replacement. I see that inlinetube has them listed for $85. Apparently there are a couple different styles, depending on whether this was a disk brake conversion (which mine was obviously) or if the car came equipped with front disks. Not sure what the difference is, and I don't know if the 3/16" rear line that our cars came equipped with, verses the 1/4" line found in later models will affect which valve I should use. My thought there is since the job of the valve is to control pressures between the front and the back (disks require 3X the pressure of a drum brake) that different line sizes could affect that. Maybe I'm making it more complicated than it is.
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Post by stan65cutlass on Aug 15, 2011 15:19:43 GMT -5
[Are you saying I should open up both a front and rear bleeder screw, and then pump the brakes?[/quote]
no, just the fittings on the prop valve itself, crack one open then close it,then open the other,have had pressure on one side before and it wouldnt let the valve centre
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Post by mongoose on Aug 15, 2011 19:27:43 GMT -5
While trouble shooting, I have remove both the master cylinder to proportioning valve lines. Would that do what you suggest? Or does it need to be the output ports of the valve?
BTW... a new valve is on its way from inlinetube.
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