I have a 96 Sentra 1.6 Man Trans, No ABS. After changing the brakes and rotors, when I went to test them, I found that I had no brake pressure on the pedal. We bled the system to find there was still no pressure. When I inspected the brakes, I found the driver's side brake line (metal) was crimped (the car was recently in an accident, and that damage was not noticed until we changed the brakes). After replacing the brake line and hose we had the same problem, so we replaced the master cylinder with a new one from cardone. After bench bleeding the master cylinder, bleeding it on the car, then connecting the lines and bleeding (Rear R, Front L, Rear L, Front R as it says in the Haynes Repair Manual) we had pressure with the car off, but not while the car is on. As soon as the ignition is turned on, the pedal goes to the floor with zero effort, and the brakes don't grab until the very end of the pedal travel. After researching online and getting a few different opinions, we opted to change the power booster as well (Reman'd from cardone). After re-bleeding the master cylinder, installing the booster, and bleeding the system, still the same problem. As far as we can tell, no hoses are flexing or expanding, and there are no leaks. We have bled the system numerous different times using numerous different techniques, we are pretty much sure there is no air in the system (there's plenty of pressure with the car off) and we use a brand new bottle of prestone DOT 3 fluid every time we bleed just to be careful. When I was under the car, it looks like the Front Right caliper is not moving as well. I have changed five sets of brakes before and never had to go beyond bleeding the system a few times. I'm at a loss, PLEASE HELP!
regarding bleeding the brakes, also make sure the the bleeder screws are facing up. someone could have placed the calipers upside down and on the wrong side. you might have to rebuild that caliper that you say is seized, or not moving.
The bleeder screws in the back are facing up, and the front screws are facing forward, calipers are on the correct sides and upright, as far as I believe.
pedal still goes to the floor and spongy even after extensive bleeding and brake line replacement, and with a "new" master cylinder? can you check pressures on each brake circuit? you might have internal leaks at the master cylinder.
Thanks for the reply azkicker!
How do we check for leaks? What kind of tool do we need? We have the day off work tomorrow so we want to get any info today/tonight so we have something to go off of tomorrow. Thank you so much!
last time i used that gauge was in school. it T's into the brake line and with the pedal applied, you can see the pressures coming from the primary and secondary pistons. although, i don't know if you can rent that out from a car parts store.
well, that tool set is mainly for last resort.
OK, so I took my car to this Service shop to have the brakes looked at. He diagnosed the problem and called me within half an hour to tell me what the problem is. The problem was that the front left hub assembly needed to be replaced. The hub was making the wheel off camber so when the pedal was pressed, the caliper was straightening the wheel which used up all of the brake pressure and that is what caused the soft pedal. He also found that the left front brake hose was twisting and falling apart, causing a leak which is letting air back into the system. The master cylinder was OK after all. The power brake booster did not help at all. I am just happy to have my Sentra back on the road! I strongly suggest taking your car to the shop so you don't keep spending time and money into it when it can all be fixed for next to nothing. Leave it to the professionals for a job like this. Not only is your life at risk, but innocent people's lives are at risk also.
Again, thank you for all the help you provided! Have a fantastic evening!
---Melanie---
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