bsb1957 Posted February 2, 2011 Share Posted February 2, 2011 (edited) Hey Guys and Ladies Ive got a 90 pathfinder with 4 wheel disk brakes.I have fairly suddenly aquired a longer than normal brake pedal stroke (almost to the floor). No visible leaks,fluid is topped. With engine off i can pump the pedal 6 or 7 times to bring it back up to firm but the minute i start it the pedal drops off. The part that confuses me is that the problem started almost overnight. Any comments and suggestions are always appreciated. Thanks Edited February 2, 2011 by bsb1957 Link to comment Share on other sites More sharing options...
adamzan Posted February 2, 2011 Share Posted February 2, 2011 Two things come to mind, I woudl check the master cylinder and brake pad thickness. could be that your brakes are low and just need new pads. Link to comment Share on other sites More sharing options...
nunya Posted February 2, 2011 Share Posted February 2, 2011 leaning more towerds master cyl. since pumping them shouldnt gain you pedal back if your pads are just low. That or possibly a blown caliper that you just cant see leaking. Link to comment Share on other sites More sharing options...
sewebster Posted February 2, 2011 Share Posted February 2, 2011 Well, when you pump with the engine off you are just depleting the power brake vacuum... so when it's firm that's just plain on full-manual brakes. Nevertheless, even with power brakes the pedal shouldn't fall too far before braking happens. Probably it's unlikely that your "problem" is that your power brakes suddenly started working though... Link to comment Share on other sites More sharing options...
bsb1957 Posted February 3, 2011 Author Share Posted February 3, 2011 Thanks for the help guys.I was looking at the front pads this afternoon and they looked to me like they still had life (5/8" of material)and rotors looked good (no lines or grooves).Would a single buggered caliper give this kind of symtom.How about air in the system? If it were summer here i wouldnt be asking questions and would just be pulling things and trying to diagnose myself but its like minus 25c up here and i dont have a garage.Im just trying to this job as efficiently and quickly as possible.I put more faith in you guys and this forum for advice than anyone or any shop around here.Thanks again Link to comment Share on other sites More sharing options...
Northernpathy Posted February 3, 2011 Share Posted February 3, 2011 If T.B was closer, I would come up to give you a hand in person. And at the same time also pick up a hardbody or two that is for sale for cheap up there Yeah it sounds like a slow leak somewhere. Maybe you could borrow a neighbors car shelter for a couple hours so that you can crawl under the truck to see if anything is leaking underneath the truck? Wouldn't be super warm, but it would at least keep the wind at bay. Link to comment Share on other sites More sharing options...
OldSlowReliable Posted February 3, 2011 Share Posted February 3, 2011 Clean off your brake booster of any grime/grease, and see if your MC is leaking right there...I know mine is, and I get a similar issue Link to comment Share on other sites More sharing options...
Indigent Posted February 3, 2011 Share Posted February 3, 2011 Check the thickness of your rotors too. They may look ok, but might be too thin. I believe it is 200mm minimum, and like 260mm new. I had similar problems for a while. I went through every damned brake part BUT the rotors. I went and grabbed my $20 measuring caliper and sure enough, they were like 192mm. Let's face it, they are the last part anyone really wants to change because they are kindof a PITA to even remove. What happens is if they are too worn, the bulk of the brake fluid goes to those calipers and there isn't enough to spread all the way around, allowing your pedal to travel farther. Do yourself a favor and spend a few minutes checking that before you get too far into it. Link to comment Share on other sites More sharing options...
adamzan Posted February 3, 2011 Share Posted February 3, 2011 (edited) According to the FSM minimum brake rotor thickness should be 20 or 24 mm. It specifies 2 different types. I couldn't imagine a 260mm thick rotor Minimum for the rear is 16 mm. Edited February 3, 2011 by adamzan Link to comment Share on other sites More sharing options...
bsb1957 Posted February 6, 2011 Author Share Posted February 6, 2011 Decided to tackle it today. It turned out to be either air in the system or maybe deteriorated brake fluid(had a bit of a brownsh colour to it).When i bled the passenger rear i did seem to get a lot of bubbles with the discharge. Anyways i basically pushed out all of the old fluid and the pedal is 500% better.Thanks for all of the responses,always much appreciated. Brian Link to comment Share on other sites More sharing options...
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