k9sar Posted March 29, 2016 Share Posted March 29, 2016 (edited) 95 pathy SE. About a week ago, my brake indicator came on as my brake fluid was a little low. I went to leave work on Thursday, climbed in the pathy and stepped on the brake and the pedal went to the floor. No brakes except the little you get when stomping and hoping you don't tag the person who stopped in front of you. Investigation showed that I had a cracked rigid line that ran from the ABS unit midway back on the frame to the rear brakes, snaking across the rear axle. Unable to replace the entire line (not available anytime soon), I cut it in 2 places about a foot and a half apart, spanning the failure, and bypassed it with flexible brake hose and a couple clamps at each end. Wiped everything down, had my son stomp on the brake a few times and it was completely dry. Now, the pedal still went to the floor so I figured there was air in the lines. I used a 15ft piece of aquarium airline to run from the bleed valve to the master cylinder fill. At each wheel, I slipped the tubing on the nipple, loosened the bleed then got in and started stomping on the brake to pump fluid through the system and flush out any air. Worked great and no check-valve was needed since the system would rather draw from the master cylinder than back-draw through the tubing. I was getting good flow through the tubing and back into the master cylinder. About 50 cycles depressing the pedal quickly yielded a constant stream of fluid after the initial air flushed out. Closed the bleed and switched the tubing to the next wheel. One-man brake bleeding! BUT.. here is the issue. After bleeding the brakes and making sure everything was tight, I felt resistance in the brake pedal but it would still go to the floor. It seemed to firm if I pumped but putting constant pressure would hit the floor. I parked on a dry/clean location on the street and stomped the brakes 50 or more times to see if I had a leak. Completely dry and the master cylinder remained full. My question now is... Why the hell don't I have brakes? Edited March 29, 2016 by k9sar Link to comment Share on other sites More sharing options...
Kingman Posted March 29, 2016 Share Posted March 29, 2016 Probably still have air. Did you bleed the master cylinder and ABS valve first? Grab a helper and do a proper brake bleed. Link to comment Share on other sites More sharing options...
k9sar Posted March 29, 2016 Author Share Posted March 29, 2016 I figured all the components would bleed with the method I was using. Constant flow of fluid into the reservoir and pumping any air out through each line using the brake pedal. Just a simplified method of a normal bleed using opening/closing the bleed valves as someone else pumps the pedal. I have never had to do anything specific for the ABS unit or master cylinder. What would you do differently for them? Link to comment Share on other sites More sharing options...
adamzan Posted March 29, 2016 Share Posted March 29, 2016 Try gravity bleeding or the old fashioned way. Also you need to bleed it starting with the left rear tire. It is actually furthest from the master as the line run on the pass side frame rail. Also I'm not sure how well clamps and hose will hold up. Why not just get a roll of brake line from the parts store? Link to comment Share on other sites More sharing options...
k9sar Posted March 29, 2016 Author Share Posted March 29, 2016 The amount of fluid I pumped through the system should have been more than adequate to flush out any air (I even injected a bubble or two to monitor the flow) I started with the right rear since that one was staring me in the face after I did the repair. The bad line was the one that runs to the left rear. As for the clamps, I didn't take any chances. I overkilled it. For each end of the hose, I slid it onto the rigid line about 4 inches (what a pain in the ass) then put 3 clamps, a spring clamp in the middle, flanked by 2 mini perforated hose clamps that I tightened the hell out of. There is absolutely no leakage for this repair. As for just picking up a roll of rigid and making my own, there were so many bends that it would be a pain in the ass, then I'd have to put on flare nuts, and the main reason was that all the clamps that hold the brake lines were rusted badly and there would be no way to get into them without destroying the other 3 lines in the bundle. The way it feels is almost like there is a check-valve of sorts that is failing. I wonder if the plunger in my master cylinder is getting some flow-by. Maybe I'll replace or rebuild that next. Link to comment Share on other sites More sharing options...
hawairish Posted March 29, 2016 Share Posted March 29, 2016 Probably still have air. Did you bleed the master cylinder and ABS valve first? Grab a helper and do a proper brake bleed. Sorry to hijack a little here, but how do you bleed the master cylinder without removing the lines? I see the instructions in the FSM, but it's in the context of installation, before the lines are attached. Isn't this sort of automatic once everything is connected? Link to comment Share on other sites More sharing options...
k9sar Posted March 29, 2016 Author Share Posted March 29, 2016 Isn't this sort of automatic once everything is connected? Kinda what I thought. I've been working on cars for almost 40 years and have never done anything different than pedal-pumping and topping off the reservoir. I don't trust gravity-bleeding because it is possible that an air pocket can exist and never bleed out unless forced. Link to comment Share on other sites More sharing options...
hawairish Posted March 29, 2016 Share Posted March 29, 2016 Kinda what I thought. I've been working on cars for almost 40 years and have never done anything different than pedal-pumping and topping off the reservoir. I don't trust gravity-bleeding because it is possible that an air pocket can exist and never bleed out unless forced. Yeah, same here. I rigged up a length of vinyl tube to a water bottle and always just have someone pedal-press while I monkey the valve...just how I've always done it, has never let me down. Can't say I'm having the problem you're having, though. (In fact, I'm not having a problem...it's my buddy's R50 that seems to have a spongier pedal, but more importantly a violent shaking while hard braking, and we've ruled out a lot of things.) But, I think this might help you: http://www.agcoauto.com/content/news/p2_articleid/266 Synopsis: bad internal seal in the master cylinder is allowing fluid to "leak" back into the reservoir. Link to comment Share on other sites More sharing options...
Kingman Posted March 30, 2016 Share Posted March 30, 2016 Sorry to hijack a little here, but how do you bleed the master cylinder without removing the lines? I see the instructions in the FSM, but it's in the context of installation, before the lines are attached. Isn't this sort of automatic once everything is connected? Easy. Pump the pedal up while someone cracks the flare fittings loose on the master just like you would at a caliper or wheel cylinder. Air is easiest to bleed out at the highest point. Sure, you can pump like mad to push those air bubbles all the way down to the wheels or bleed at the master and be done with it. Up to you. Stands to reason that if the only variation here is whether or not air has entered the system, and there is a problem after air has entered the system, there is still air in the system. Pumping the pedal with the lines open isn't exactly building any pressure to push a stuck bubble out. Should what you've done work fine? Yes, not always. I'd double check like was mentioned grab a helper and do the bleed the old fashioned way. In fact do it a lot. If you have rear drums make sure they're adjusted up properly to bring back some pedal feel. Link to comment Share on other sites More sharing options...
k9sar Posted March 30, 2016 Author Share Posted March 30, 2016 Yeah, same here. I rigged up a length of vinyl tube to a water bottle and always just have someone pedal-press while I monkey the valve...just how I've always done it, has never let me down. Can't say I'm having the problem you're having, though. (In fact, I'm not having a problem...it's my buddy's R50 that seems to have a spongier pedal, but more importantly a violent shaking while hard braking, and we've ruled out a lot of things.) But, I think this might help you: http://www.agcoauto.com/content/news/p2_articleid/266 Synopsis: bad internal seal in the master cylinder is allowing fluid to "leak" back into the reservoir. Here's a small section that jumped out at me. Normal travel of the pistons and seals in the master cylinder are very limited. In a poorly maintained system, this allows corrosion to form in the area of the cylinder that is not used. When the brake lines are opened, the pistons travel much deeper into the cylinder. Corrosion can cut the seals and cause failure. Since it had basically drained of fluid in the parking lot and I drove it to dinner and then 20 miles home, hitting the floor with the pedal as I tried to milk whatever braking I could get, I wonder if I f'd up the seal(s). Might just replace the master cylinder anyway. Couldn't hurt and they aren't very expensive. 1 Link to comment Share on other sites More sharing options...
Kingman Posted March 30, 2016 Share Posted March 30, 2016 It's not unheard of. Do you own line clamps? If you can pinch off the 3 brake soft lines you'll be able to tell by whether or not the pedal still drops. Link to comment Share on other sites More sharing options...
hawairish Posted March 30, 2016 Share Posted March 30, 2016 Thanks Kingman, I'll give that a try. I don't think air has entered the system per se, but it's something we're hoping to rule out. Link to comment Share on other sites More sharing options...
k9sar Posted March 30, 2016 Author Share Posted March 30, 2016 It's not unheard of. Do you own line clamps? If you can pinch off the 3 brake soft lines you'll be able to tell by whether or not the pedal still drops. no specific line clamps but I figure a couple of popsicle sticks and a pair of vice-grips on each line should do the trick (enginerd it!) Will give isolating the wheels out of the system a try. If I still hit the floor, it's master cylinder time. Maybe I'll have my kid push the pedal while I use a stethoscope in the master cylinder. If there is flow-by, I should be able to hear it Link to comment Share on other sites More sharing options...
Slartibartfast Posted March 31, 2016 Share Posted March 31, 2016 Needle nosed vise grips with fuel hose on the tips are supposed to work pretty well. Link to comment Share on other sites More sharing options...
Kingman Posted March 31, 2016 Share Posted March 31, 2016 Anything to not cut the hose Link to comment Share on other sites More sharing options...
k9sar Posted April 1, 2016 Author Share Posted April 1, 2016 I guess I'm still not convinced it's the master cylinder and not perhaps the ABS module. Clamping the hoses going to the wheels will only take them out of the equation and if the pedal still goes to the floor, all I know is that the issue (possibly air) is in the wheel area. What I really need to do it isolate the master cylinder. Now, I can either remove the 3 brake lines from the master cylinder and plug those ports, then test the pressure or... maybe install a feature that will allow me to prevent bleedout if another line splits. If I put flex hose (about 6 inches to cover a 3-inch gap) in each of the rigid lines, just after they leave the master cylinder, I can isolate the master cylinder, any of the wheels, the entire rear system including ABD, or any combination thereof. Can also prevent losing fluid and drawing lots of air into each line if I have to replace the MC. Any bobbles at that point would be at the MC and can be reverse-bled quickly and easily without flushing air through the entire system. Hmmmm... still thinking about this. I talk my way through several variations, pros and cons, while I sit around in the evening. Drives my wife nuts. I occasionally get the "Quit re-engineering it" comment from her. I guess she's right. Changing things to make it easier for future work..... on a 20+ year old truck with over 240000 miles.... she has a point. Link to comment Share on other sites More sharing options...
Cuong Nguyen Posted April 1, 2016 Share Posted April 1, 2016 But did you bleed the abs module? I didn't think I saw you say so. Sent from my SAMSUNG-SM-N920A using Tapatalk Link to comment Share on other sites More sharing options...
k9sar Posted April 1, 2016 Author Share Posted April 1, 2016 yep. gonna rebleed everything after I install a pinch-point and check again... just in case... cause throwing money at a MC if not needed would suck Link to comment Share on other sites More sharing options...
Cuong Nguyen Posted April 2, 2016 Share Posted April 2, 2016 yep. gonna rebleed everything after I install a pinch-point and check again... just in case... cause throwing money at a MC if not needed would suckI have my old MC if you want. It was brand new 7 years ago after I swapped to a bigger mc. Now that was a waste lol. Sent from my SAMSUNG-SM-N920A using Tapatalk Link to comment Share on other sites More sharing options...
k9sar Posted April 2, 2016 Author Share Posted April 2, 2016 Well, I bled all my lines again. LR, RR, LF, RF and ABD unit. Still mushy brakes. Crap. Should be better weather tomorrow to isolate the MC and verify that is the problem... then to get one. What were you thinking for price shipped to 19468 Cuong? Link to comment Share on other sites More sharing options...
Kingman Posted April 3, 2016 Share Posted April 3, 2016 Blocking the lines off (line clamps) will entirely seal off air past that point. If you did that and the brake pedal was hard as a rock, the issue is not there or the ABS module. If it was still mushy, the issue is the master cylinder or ABS module. More likely the master cylinder. If the brake pedal was hard after pinching the lines off, but still mushy after bleeding again, I'd suggest adjusting the rear drums up if that's what your truck has for rear brakes. That's commonly mistaken for air in the lines. Link to comment Share on other sites More sharing options...
PathyAndTheJets Posted April 7, 2016 Share Posted April 7, 2016 The drums should be adjusted to drag slightly. You should feel some resistance, and hear the shoes making a shhhhft sound as you turn the wheel. The brakes auto adjust as you apply the parking brake as well. Link to comment Share on other sites More sharing options...
Cuong Nguyen Posted April 7, 2016 Share Posted April 7, 2016 Well, I bled all my lines again. LR, RR, LF, RF and ABD unit. Still mushy brakes. Crap. Should be better weather tomorrow to isolate the MC and verify that is the problem... then to get one. What were you thinking for price shipped to 19468 Cuong? The Mc I have is for disks all around but if you want it, I'll take 10 plus shipping. Sent from my SAMSUNG-SM-N920A using Tapatalk Link to comment Share on other sites More sharing options...
k9sar Posted April 8, 2016 Author Share Posted April 8, 2016 Found a guy local who will do a rebuild for fairly cheap so I think I'm covered if I need. I have disc all around and what I find interesting is that I can get no answer from any manufacturer as to the difference in MCs for a 95 pathy between disc and drum brakes. In fact, Dorman even stopped making the one for 4-disc and now list the same MC for either configuration. Link to comment Share on other sites More sharing options...
PathyAndTheJets Posted April 8, 2016 Share Posted April 8, 2016 I bet it's the same, but there is a residual pressure check valve somewhere in the line for drum systems. Link to comment Share on other sites More sharing options...
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