Mike, thanks for all the help ! Let me clarify my many issues. Break fluid is pushing out from under the lid, while its on! The rear reservoir empties into the front, thus making it overflow. The vacum is so great that the rubber gasket on the rear reservoir sucks our (the circular piece in the center of the gasket. I will attempt to bleed again as I think I might have only had one strap on the lid to the m/c. Thanks for helping me in my desperation...reno has nobody that can come close to helping me.this proportioning valve is driving me nuts too, cant tell if I need to push the "bleeder button" in while bleeding or just not let the bleed button push out while manual pumping the brakes. ? any ideas?
brake bleeding round 3
- Thread starter elyNV
- Start date
I feel like I am coming in during the intermission so forgive me if I state the obvious.
I have done many brake jobs over the years and the best tool I ever purchased to make the job easier was a pressure bleeder. Not only did it bleed the brakes quicker but it made it possible for me to do the job by myself.
You have changed so many different parts of the system it is going to be hard to discover which part is causing you problems.
At this point I would suggest you start at the beginning--the brake system on your rig is still pretty basic and there can only be a couple of things that could be causing you grief. And remember, just because you put a new/reman part on doesn't mean the new/reman part is a good part. I have taken back more than a couple of reman mc's that were no good out of the box.
Good luck and keep us posted as to your progress.
I have done many brake jobs over the years and the best tool I ever purchased to make the job easier was a pressure bleeder. Not only did it bleed the brakes quicker but it made it possible for me to do the job by myself.
You have changed so many different parts of the system it is going to be hard to discover which part is causing you problems.
At this point I would suggest you start at the beginning--the brake system on your rig is still pretty basic and there can only be a couple of things that could be causing you grief. And remember, just because you put a new/reman part on doesn't mean the new/reman part is a good part. I have taken back more than a couple of reman mc's that were no good out of the box.
Good luck and keep us posted as to your progress.
Re: brake bleeding round 3 !!
Did as instructed, system has been bled with new calipers. Break pads rub enough on the disk to make the calipers hot (very hot) which in turn seems to make the piston on the caliper close, thus making the problem worse(guessing the fluid us getting so hot it is expanding, causing the piston on the caliper to close). By the time I return home the truck is stopping by itself. Strange thing is, the breaks work great. Just appears that the pads are dragging to much or the piston is not releasing enough......??? I have dot 3 break fluid in it. Thanks
Did as instructed, system has been bled with new calipers. Break pads rub enough on the disk to make the calipers hot (very hot) which in turn seems to make the piston on the caliper close, thus making the problem worse(guessing the fluid us getting so hot it is expanding, causing the piston on the caliper to close). By the time I return home the truck is stopping by itself. Strange thing is, the breaks work great. Just appears that the pads are dragging to much or the piston is not releasing enough......??? I have dot 3 break fluid in it. Thanks
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
Pull the master cylinder away from the booster (hydraulic lines should have enough slack to allow this without disconnecting). "shorten" the push rod between the mc and the booster by two revolutions only and then re-test.
Mike, thanks for the quick response. I have done as you instructed. So here is what I have observed. Fluid is leaving the m/c and I can see fluid returning (movment in the reserviour when the peddle is released. I am officially defeated!! The rear works fine, the driverside works fine, the passenger side does not release enough creating too much drag (I am able to spin it with force) I have tried two different set of pads, two different calipers, width of rotors is the same on both sides. I even took the line off at the caliper to see if I could blow fluid back up the line, it did. Fluid dribbled out a little when I seperated it from the caliper, I dont think it was enough to be considered line pressure. I am out of guesses. Maybe the brand new Skyjacker braided line is funky? I am going to research brake shops in reno I guess.....unless you got something up your sleave ???thanks a ton for all your help..
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
Ok, more new information!
If, it is only the passenger-side caliper that is not releasing, then something is causing the caliper piston to not be "retracted" by the wiping action of the piston seal when mc pressure is released.
If both front calipers were not releasing fully, I'd say the residual pressure valve in the outlet port of the master cylinder is bogus. The rpv for the disc brake system is a nominal 2psi, much lower than for the drum brake system (a nominal 8>10psi.
So something in the passenger side circuit (between the proportioning valve and the caliper piston is not allowing pressure to release fully. I'd look for something acting as a check valve in that circuit only. As it gets hotter and hotter from "pad drag", then the fluid expands resulting in increasing brake "apply" pressure only on the passenger caliper. Once it cools down, it probably works "normally" (but no doubt it pulls to one side when brakes are applied) until it starts dragging again and the cycle repeats.
Remove the line from the front junction block to the passenger side caliper and verify complete fluid flow both directions. That is from the caliper directly to the junction block, that is one part of the circuit, that only has to do with the passenger side.
If the flex hose was oem, I'd say it's definitely rotted internally and the inner ply acts like a one-way valve, real common failure issue on any brake system. But if the hose itself is a new replacement item, then that would be a remote possibility, but check it anyway, it could be defective, don't rule that out!
By verifying flow both directions in only the plumbing portion of the passenger side, you are trying to rule out anything acting as a check valve. But in the past, I have seen deteriorated oem hose material sluff off inside the hose and then start moving through the plumbing where it then acts as an intermittent restriction!
If, it is only the passenger-side caliper that is not releasing, then something is causing the caliper piston to not be "retracted" by the wiping action of the piston seal when mc pressure is released.
If both front calipers were not releasing fully, I'd say the residual pressure valve in the outlet port of the master cylinder is bogus. The rpv for the disc brake system is a nominal 2psi, much lower than for the drum brake system (a nominal 8>10psi.
So something in the passenger side circuit (between the proportioning valve and the caliper piston is not allowing pressure to release fully. I'd look for something acting as a check valve in that circuit only. As it gets hotter and hotter from "pad drag", then the fluid expands resulting in increasing brake "apply" pressure only on the passenger caliper. Once it cools down, it probably works "normally" (but no doubt it pulls to one side when brakes are applied) until it starts dragging again and the cycle repeats.
Remove the line from the front junction block to the passenger side caliper and verify complete fluid flow both directions. That is from the caliper directly to the junction block, that is one part of the circuit, that only has to do with the passenger side.
If the flex hose was oem, I'd say it's definitely rotted internally and the inner ply acts like a one-way valve, real common failure issue on any brake system. But if the hose itself is a new replacement item, then that would be a remote possibility, but check it anyway, it could be defective, don't rule that out!
By verifying flow both directions in only the plumbing portion of the passenger side, you are trying to rule out anything acting as a check valve. But in the past, I have seen deteriorated oem hose material sluff off inside the hose and then start moving through the plumbing where it then acts as an intermittent restriction!
Mike you were dead on with bringing the push rod back. I moved it back two full turns as instructed rebled the system and to date pads are not heating up!!! Yeaaaaa. I do still have a pulling to to passenger side when braking issue and now the peddle enages the brakes further into the peddle, but beggars can't be choosers! Thanks for all the help, I would be unable to stop or unable to go if you were'nt around, thanks !!!! I might try turning the rod back out 1 turn and see what happens as well as changing out the pads.....
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
Wonderful! Persistence pays in the end!
I've experienced this same thing many times, not just with IH schnizz!
If ya wanna keep playing, I'd now increase the pushrod length by only 1/2 turn! There is a very fine line between perfect and scruud! Your pedal will then come back once you hit the sweet spot! Even though the pedal has mucho travel, the actual booster piston and the mc piston hardly travel/move at all.
All that verbage in the IH service manual regarding setting the pushrod length on a vacuum brake booster is only for the oem parts or actual IH-boxed parts obtained from a dealer back ion the day. While the process is the same for using over-the-parts-counter aftermarket stuff, the dimensions are not. Every manufacturer/supplier of those parts will have a slightly different "stack" to the dimensions since their parts are not identical in the depth of the mc piston hole, the contact point in the vac booster, etc.
When you buy a "reman" combination booster/master cylinder that is already assembled, the length of the pushrod was set before the assembly was put together by the remanner, ya rarely have to go in and do surgery on those. But when ya buy the parts separately, who knows what dimensions you will end up with?
I still think that the problematic caliper is "hanging" the piston in it's bore due to the boot not "flexing" as it should. But...as you accumulate some miles, it May very well start working normally since the calipers are "self-adjusting". Just be careful when stopping and anticipate a pull! The same thing will occur on drum front brakes if the self adjusters are not operating properly or the adjustments are badly out of sync side-to-side.
I've experienced this same thing many times, not just with IH schnizz!
If ya wanna keep playing, I'd now increase the pushrod length by only 1/2 turn! There is a very fine line between perfect and scruud! Your pedal will then come back once you hit the sweet spot! Even though the pedal has mucho travel, the actual booster piston and the mc piston hardly travel/move at all.
All that verbage in the IH service manual regarding setting the pushrod length on a vacuum brake booster is only for the oem parts or actual IH-boxed parts obtained from a dealer back ion the day. While the process is the same for using over-the-parts-counter aftermarket stuff, the dimensions are not. Every manufacturer/supplier of those parts will have a slightly different "stack" to the dimensions since their parts are not identical in the depth of the mc piston hole, the contact point in the vac booster, etc.
When you buy a "reman" combination booster/master cylinder that is already assembled, the length of the pushrod was set before the assembly was put together by the remanner, ya rarely have to go in and do surgery on those. But when ya buy the parts separately, who knows what dimensions you will end up with?
I still think that the problematic caliper is "hanging" the piston in it's bore due to the boot not "flexing" as it should. But...as you accumulate some miles, it May very well start working normally since the calipers are "self-adjusting". Just be careful when stopping and anticipate a pull! The same thing will occur on drum front brakes if the self adjusters are not operating properly or the adjustments are badly out of sync side-to-side.