Slartibartfast Posted February 5, 2013 Share Posted February 5, 2013 A few weeks ago, my ABS and BRAKE lights came on. I added a little fresh brake fluid to the master cylinder and forgot about it, figuring the pads were wearing or something. Well, the lights came on again today, and sure enough the fluid was low. When topping up the cylinder, I noticed that the plastic reservoir is loose relative to the metal piece under it. When I wiggled the res I could see a little fluid moving around between the plastic and the metal (like when you get water between a glass top and a table). I assume this is my leak. I don't see any drip marks but there is a far amount of black gunk stuck to the metal. (I'll get pics tomorrow when it isn't dark and freezing outside.) Anyone had this happen? Is it a simple O-ring job or am I looking at a whole new MC? (Also, is it safe to drive in this condition? It appears to be a very slow leak in a non-pressurized area, and the idiot lights kick in well before it would run dry, but given that my E-brake is about as effective as trade sanctions, I'd rather be sure.) Link to comment Share on other sites More sharing options...
Trogdor636 Posted February 5, 2013 Share Posted February 5, 2013 Master cylinders became so cheap at one point ( I'm obviously talking aftermarket) that rebuilding it isn't worth my time anymore. I just throw a new one in there. Link to comment Share on other sites More sharing options...
Precise1 Posted February 5, 2013 Share Posted February 5, 2013 MWS wrote up a blerb on rebuilding his MC. His attitude is if you have a good bore/piston, just change the seals and don't wind up with a poorly manufactured/remanufactured one. That said, I haven't done it and don't know how available the rebuilt kits would be. Yes, it should be ok to drive on for a little while as long as it doesn't suck any air. and yes, it should just be a seal replacement. Clean up below it or put something under it (cut up/wedge in a plastic container or something) to try to catch the fluid so you can monitor the leak, and obviously keep an eye on the level regularly. Also, you may want to check on the piston rod that comes into the cabin for fluid, as well as a spot check at each wheel. B Link to comment Share on other sites More sharing options...
Slartibartfast Posted February 5, 2013 Author Share Posted February 5, 2013 (edited) Thanks guys, I checked under it today and found no brake fluid leaks. I checked behind the res and sure enough, fluid and gunk everywhere. Looks like the rearmost seal has crapped out. I checked the exploded view in the FSM and sure enough, looks like there are two rubber seals that the res apparently just presses into. Any ideas on where to get these separately? A rebuild kit looks to cost about as much as a reman MC. Edited February 5, 2013 by Slartibartfast Link to comment Share on other sites More sharing options...
adamzan Posted February 5, 2013 Share Posted February 5, 2013 Looks like the seals are about 3 dollars each on courtesy parts. I'd rather have a refreshed oem one than parts store junk. http://www.courtesyparts.com/pathfinder-parts-wd21-1987-1995/genuine-nissan-parts/brake/460-brake-master-cylinder/-c-5572_5573_5674_5678.html Link to comment Share on other sites More sharing options...
Slartibartfast Posted February 6, 2013 Author Share Posted February 6, 2013 Awesome, thanks for the link! Link to comment Share on other sites More sharing options...
Slartibartfast Posted February 6, 2013 Author Share Posted February 6, 2013 Stupid question, does anyone know how the res comes off the cylinder? Looks to me like it just wiggles off, but is there a clamp or a clip or something I'm not seeing? Link to comment Share on other sites More sharing options...
Alkorahil Posted February 8, 2013 Share Posted February 8, 2013 (edited) Stupid question, does anyone know how the res comes off the cylinder? Looks to me like it just wiggles off, but is there a clamp or a clip or something I'm not seeing? Yes it does. It is a tight fit, those o rings are beefy. HINT: a stock Nissan master cylinder will come with the res and a new cap. every after market one I have seen for these trucks does not come with it. Edited February 8, 2013 by Alkorahil Link to comment Share on other sites More sharing options...
Slartibartfast Posted February 9, 2013 Author Share Posted February 9, 2013 Cool, thanks! Hopefully I can get the res off without buggering it. (Not a BFH job!) Since I've never done brakes before my uncle's helping me do the bushings and flush the fluid (needed it anyway). He's convinced himself that it's got some sort of 'shuttle' somewhere in the system that preserves one set of brakes if the others fail, which means he'd need a special tool to bleed them. The FSM makes no mention of this, except maybe the load sensing valve, which mine doesn't have anyway. Do we need anything special for the job, or has my uncle just been spending too much time under GM products? Link to comment Share on other sites More sharing options...
Towncivilian Posted February 9, 2013 Share Posted February 9, 2013 (edited) Nope, you don't need anything special for bleeding. Just follow the bleed order. WD21s don't have LSVs, they're only on Hardbodies as you've said. Edited February 9, 2013 by Towncivilian Link to comment Share on other sites More sharing options...
adamzan Posted February 9, 2013 Share Posted February 9, 2013 Just bleed it in the order the FSM says. Which includes the ABS actuator on the passenger side frame rail. Link to comment Share on other sites More sharing options...
Towncivilian Posted February 9, 2013 Share Posted February 9, 2013 Oops, my memory failed me there. I forgot about that, my bad! Link to comment Share on other sites More sharing options...
Slartibartfast Posted February 9, 2013 Author Share Posted February 9, 2013 Thanks guys! Link to comment Share on other sites More sharing options...
Trogdor636 Posted February 9, 2013 Share Posted February 9, 2013 Unhook your battery and unplug the ABS actuator before you bleed as well. My ABS and brake light wouldn't go out until I did it that way. Link to comment Share on other sites More sharing options...
Slartibartfast Posted February 15, 2013 Author Share Posted February 15, 2013 Good news and bad news... the bushings went in pretty easily, but when I pumped the brakes to test them, fluid came bubbling out of a threaded hole in the side of the master cylinder. My uncle's ordered a new master and we're going to install it tomorrow. I had no idea the fluid was coming out there. Come to think of it I have no idea why there's a hole there. Link to comment Share on other sites More sharing options...
Trogdor636 Posted February 15, 2013 Share Posted February 15, 2013 Wha? Take a picture, I'm curious. Link to comment Share on other sites More sharing options...
Slartibartfast Posted February 15, 2013 Author Share Posted February 15, 2013 Link to comment Share on other sites More sharing options...
Alkorahil Posted February 16, 2013 Share Posted February 16, 2013 plug missing! Link to comment Share on other sites More sharing options...
devonianwalk Posted February 16, 2013 Share Posted February 16, 2013 Holy Schnikes! Link to comment Share on other sites More sharing options...
Precise1 Posted February 16, 2013 Share Posted February 16, 2013 That happened to a buddy of mine. All it needed was plug? B Link to comment Share on other sites More sharing options...
Slartibartfast Posted February 16, 2013 Author Share Posted February 16, 2013 Is that where the bleeder should be? Do these go AWOL often? Looks like I'll have a spare MC, since the part's already on its way. Link to comment Share on other sites More sharing options...
adamzan Posted February 16, 2013 Share Posted February 16, 2013 My old truck weeped from there, but my new rig doesn't and I don't see a plug. Link to comment Share on other sites More sharing options...
adamzan Posted February 16, 2013 Share Posted February 16, 2013 This pictures on this page may provide some insight, looks like there is a plug in there. http://nissannut.com/projects/SAS_brakes/ I think when I have the extra cash/time I will do this upgrade. Link to comment Share on other sites More sharing options...
devonianwalk Posted February 16, 2013 Share Posted February 16, 2013 Yeah, mine has the same hex bolt in place. Link to comment Share on other sites More sharing options...
Slartibartfast Posted February 16, 2013 Author Share Posted February 16, 2013 Pathy got a new master cylinder today (PBR from Carquest). Check out what it doesn't have: My uncle says the hole on the old one is where a ball bearing is installed and crimped in place to seal it, and that it isn't uncommon for the seal to fail. Upon closer inspection what I thought was a threaded hole looks more like a hole full of crud. I brought the dead MC home in a bag so I can dissect it and figure it out for sure. It had clearly been leaking for a while... the brake booster lost a lot of paint when I went to wipe the fluid off. We bled it with a vacuum bleeder (pulled the ABS fuse). I'm not sure yet if the pedal feels normal but then I've been driving my dad's R50 so my points of reference are shot. It does seem to stop properly but I'll keep an eye on it. Dissection pics/results to come... Link to comment Share on other sites More sharing options...
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