chief351 Posted September 2, 2007 Share Posted September 2, 2007 Need help troubleshooting. Problem is a soft pedal. When braking it starts out with the regular feel to the pedal and the brakes grab however the pedal slowly continues to the floor and braking power diminishes. I am estimating I have about 40-50 % braking left. A little history - Both my front/rear brakes were new 5000 miles ago. They have been lightly used and basically show no signs of wear. The brakes worked perfectly on a family vacation 2 weeks ago which entailed driving 1200 miles and towing a 3500 lb boat for 400 miles. This problem occurred 6 days ago without warning and since then I have bled the entire braking system once which did not solve the problem. Last night I changed the wheel cylinders because the originals appeared to have seized however upon inspection I realized that they just needed a tune up. I replaced the wheel cylinders anyway since I had purchased them and did not cost a lot of $$$ and adjusted them. So the rear brakes were bled a second time and then I test drove the vehicle and the soft pedal was still there. I loosened off the master cylinder and did not note any moisture or obvious problems. Under the dash where the brake pedal enters the firewall appears ok with no moisture. I removed the valve in the vacuum line and blew it out but that did not help either. I am reluctant to just change out the MC since it costs $350 here in Canada fearing that is not the problem. There are no visible leaks in the system and have never found any fluids underneath this vehicle. The resevoir on the MC has not changed ever. If this vehicle has the proportioning valve, which has been discussed on this board, I cannot find it, and yes I did look on the passenger frame rail for it. If anyone has anything to add or share I am "all ears" as I need this thing ready to go ASAP. The wife is getting cranky without the truck so the pressure is on and I refuse to get %#@ed at the dealership so it ain't going there. Thanks in advance Chief 95 XE Pathy 120000 miles, auto. Link to comment Share on other sites More sharing options...
94extreme Posted September 2, 2007 Share Posted September 2, 2007 (edited) my first thought is the MC or you just have leak in the system somewhere. iirc mine, when it went, didn't leak externally. just the soft pedal where i'd lose all the power.. i'd say less then the 50% you think you may have.. did you pump the pedal and was there any difference? oh, hope you re-bled the system after loosining and opening things in it. one more thing. how are the front rotors and have you ever changed the hoses at either end.? Edited September 2, 2007 by mzxtreme Link to comment Share on other sites More sharing options...
88pathoffroad Posted September 2, 2007 Share Posted September 2, 2007 A MC shouldn't cost that much. Have you checked local parts stores or online retailers? $55-$79 on rockauto.com... Link to comment Share on other sites More sharing options...
chief351 Posted September 2, 2007 Author Share Posted September 2, 2007 Thanks for the responses guys. I just bled the entire system again as well I found the proportioning valve and bled that too. I have inspected the calipers for leaks too and found none, as well I checked the lines for any moisture and found none. So I am thinking it is the master cylinder. It must be a bad seal inside of it - however it must be tiny for me to still have decent brake pedal feel. As for the $$$ 88Pathy - I live in Canada and the prices can be ridiculous. The local part stores are actually more expensive than the dealer on the master cylinder for whatever reason. Nissan has a rebuild kit for $33 so I will probably go for that. I will be very confused if the MC does not fix this. Thanks again for your help Chief Link to comment Share on other sites More sharing options...
chief351 Posted September 10, 2007 Author Share Posted September 10, 2007 Just an update on my problems: Master cylinder replaced - hard to say if it helped Wheel cylinders replaced - ditto Clean and adjust rear drums - helped a little Removed front pads, sanded, cleaned calipers up - no change Bled proportioning valve - no change Played with adjusting rod attached to back of brake pedal - helped the feel of the brakes After each of these steps I would usually bleed the brake system, and/or, bleed the brake I was working on and it's partner, so if I was working on the front left then I would bleed both front brakes. In total I think the system has been bled 6 times. After many test drives and many panic stops I started to realize a "pull" to the left. I took apart the calipers a couple of times and cleaned them, lubed them, and buttoned them back up. Nothing seemed to help. Then I put some wood between the caliper and had the wife depress the pedal. What I noticed was that I only had one piston working on the right caliper !!! Fearing the worst I pulled the pistons out and cleaned the gunk off of them. There was very very minor pitting on both pistons but I put them back anyway and bled that brake again. I just got back from a test drive and am very happy to say the least. Another question for the WD21 folks - with oversized tires are you able to lock the brakes up with ease? I am running the 6 spoke gunmetal grey supercharged X-Terra rims with 245/70/17 off road tires and they are heavy. Link to comment Share on other sites More sharing options...
unccpathfinder Posted September 10, 2007 Share Posted September 10, 2007 (edited) when you say proportioning vavle is this the ABS valve on the RH frame rail or the load sensing valve? there is a specific order (according to the FSM on the order to do it) I know we had problems with Wheelmans pathy and the ABS valve capturing air and then everything would be good and when the valve would actuate it would put air in the lines...when I did my truck I put almost an entire quart through it and didnt have any issues with a soft pedal I prefer to do Gravity Bleeds (open bleeder valve and let fluid naturally flow out) then go through and I ususaly go around the truck 2 times after I get no air coming out of the bleeders...heres a copy of the correct order from the FSM Edited September 10, 2007 by unccpathfinder Link to comment Share on other sites More sharing options...
94extreme Posted September 10, 2007 Share Posted September 10, 2007 i have 31" muds on stock steel rims and it's darn hard to make an emergency stop.... very hard. when empty, i can barely lock them up... if loaded, not even close. Link to comment Share on other sites More sharing options...
Simon Posted September 10, 2007 Share Posted September 10, 2007 I can lock up my 33" MT's in an emergency stop situation. mz, I'd suspect you've got some brake system issues if you can't lock up your 31" tires. Link to comment Share on other sites More sharing options...
chief351 Posted September 11, 2007 Author Share Posted September 11, 2007 Thanks for the responses guys! So that diagram/instruction page posted above - I have a question. Although everything seems to be working ok now is it advisable to bleed the entire system one more time in that order? And what about that ABS valve I have (I have rear drum ABS setup) do I need to bleed it or not bleed it or do something else with it? Thanks again Chief Link to comment Share on other sites More sharing options...
94extreme Posted September 11, 2007 Share Posted September 11, 2007 mz, I'd suspect you've got some brake system issues if you can't lock up your 31" tires. i don't know.. they are a little soft but i haven't been able to figure why. they work though. Link to comment Share on other sites More sharing options...
rennwerkes Posted September 11, 2007 Share Posted September 11, 2007 i don't know.. they are a little soft but i haven't been able to figure why. they work though. I usually recommend pressure bleeding. When you use the "pump the brake pedal" method you sometimes push the piston further than it's normal operating span. What happens is that the crud that get built up on the areas that don't come into contact with the seals can then cause the seals to degrade and loose a perfect seal. This would end up causing a "soft" pedal feel. Seen it happen several times in the past. Link to comment Share on other sites More sharing options...
94extreme Posted September 11, 2007 Share Posted September 11, 2007 i can see that as the fluid is pretty dark, even after multiple "pump the pedal" flushes.. hmmm.. thanks Link to comment Share on other sites More sharing options...
rennwerkes Posted September 11, 2007 Share Posted September 11, 2007 Hmmm...fluid shouldn't be dark. Did you bleed almost to empty and then refill with fresh fluid? Make sure you're using at least DOT 4 fluid. Link to comment Share on other sites More sharing options...
chief351 Posted September 13, 2007 Author Share Posted September 13, 2007 I have to laugh now. I was just out for a drive. Tried a couple of emergency stops and things went well. Once back into town I could feel the pedal getting mushy. I was pisst-off to say the least. Fortunately I was not far from home. I get'er back into the garage and I smell brake fluid and check the master cylinder which is almost empty. I look under the truck and see a puddle at the back right. So I take a closer look and notice where the tab holds the brake line to the axle is all rotted out and it's dripping. I wipe the undercoating away and have a friend push on the pedal and it starts squirting out of this pin hole. What the #$ll are the chances? What next? Replacing the line tomorrow, hopefully it will go smoothly. Chief Link to comment Share on other sites More sharing options...
rennwerkes Posted September 13, 2007 Share Posted September 13, 2007 I have to laugh now. I was just out for a drive. Tried a couple of emergency stops and things went well. Once back into town I could feel the pedal getting mushy. I was pisst-off to say the least. Fortunately I was not far from home. I get'er back into the garage and I smell brake fluid and check the master cylinder which is almost empty. I look under the truck and see a puddle at the back right. So I take a closer look and notice where the tab holds the brake line to the axle is all rotted out and it's dripping. I wipe the undercoating away and have a friend push on the pedal and it starts squirting out of this pin hole. What the #$ll are the chances? What next? Replacing the line tomorrow, hopefully it will go smoothly. Chief If one line is bad I'd guess the rest are in similar condition. If you can, change them all. Not sure about Nissans but sometimes braided lines are cheaper than OEM and better. Link to comment Share on other sites More sharing options...
unccpathfinder Posted September 13, 2007 Share Posted September 13, 2007 (edited) braided lines are nice but expensive...brake lines are pretty cheap and pick up a bender and a flaring tool and I think you could redo all of your brakes for about 1/2 the cost of braided lines..get a brake line wrench it will make life easier b/c a reg wrench will round them off...lost of experience on this and it sucks b/c then you get into the vice grips and channel locks...makes a nasty mess for the next person...and i have been on the giving and receiving end of that 1 Edited September 13, 2007 by unccpathfinder Link to comment Share on other sites More sharing options...
rennwerkes Posted September 13, 2007 Share Posted September 13, 2007 braided lines are nice but expensive...brake lines are pretty cheap and pick up a bender and a flaring tool and I think you could redo all of your brakes for about 1/2 the cost of braided lines..get a brake line wrench it will make life easier b/c a reg wrench will round them off...lost of experience on this and it sucks b/c then you get into the vice grips and channel locks...makes a nasty mess for the next person...and i have been on the giving and receiving end of that 1 Not always. There are some factory brake lines that are more expensive than braided ones. However, after reading the post about the leak I think you're right about it being the metal portion. I thought it was the rubber part. Regardless, I'd check all the lines just to make sure the other sides aren't in the same condition. Link to comment Share on other sites More sharing options...
unccpathfinder Posted September 13, 2007 Share Posted September 13, 2007 ahh good point I forgot about the rubber hoses up front...I was just thinking about the rear axle which I dont relaly see the need to put the braided back there but we did it on wheelmans and they were pretty pricey from what he said and then it kinda leaves the lines out there to snag something and rip off...but yea up front the steel braids may be nic Link to comment Share on other sites More sharing options...
Simon Posted September 13, 2007 Share Posted September 13, 2007 Make sure the braided lines aren't too long. Some aftermarket ones are quite a bit longer than stock. SkinnyPedal had braided lines on the front of his WD21, and ended up having one rub on the tire, and blow out on a major highway. He was lucky he didn't hit anything. He has since gone back to stock rubber lines. Link to comment Share on other sites More sharing options...
chief351 Posted September 17, 2007 Author Share Posted September 17, 2007 Fixed up the rear brake lines. Used the bending tool - worked great. Cost was only 6 bucks so that made me happy. While putting the lines back into the splitter on the axle one of them striped the splitter on me. What a pain in the ass. Went to the wrecker and got one for 10 bucks, Nissan wanted 40. So I got'er buttoned up last Thursday night and have been driving it to work - so far so good. Actually it is the best it has ever been. Taking a road trip soon so will report back with any problems. Thanks for the help guys Chief Link to comment Share on other sites More sharing options...
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