proxlamus© Posted May 3, 2007 Share Posted May 3, 2007 Ugh.. everything that can go wrong does I changed over to rear discs today, and my car is a piece of crap. "L" went to the drivers side. "R" went to the pass side 240sx calipers 280zx (83) rotors Maxima brackets everything is sealed, and there are no leaks. the bleeder is above the brake line I have gone through half a bottle of fluid now. Process is rear right (pass) rear left (drivers) front right (pass) front left (driver). I have done this process about 5 times all the way around. Bleeding each about 5-6 times. No bubbles no air. The pedal has some pressure but it goes to the floor. I am not using a proportioning valve for now. My drums were grinding and I needed to quick fix. I understand that I wont have clamping force on the rear, but does this explain my lack of pressure? cant get any pressure. help Quote Link to comment Share on other sites More sharing options...
GrommitZ Posted May 3, 2007 Share Posted May 3, 2007 Did you bleed the master cylinder? Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted May 3, 2007 Author Share Posted May 3, 2007 I have not. thats a very good idea. Why would I be able to squirt fluid out of the calipers with no air bubbles, but air trapped in the master cylinder?! Quote Link to comment Share on other sites More sharing options...
GrommitZ Posted May 3, 2007 Share Posted May 3, 2007 I've seen this several times lately. Pushing the pedal still compresses the air, which in turn squirts out the brake fluid at the other end. To get the air out, I've had to open the MC bleeder valves quickly but far enough(without bottoming the pedal) to get the air that's stuck at the top of the master cylinder, but below the reservior. Good luck. Quote Link to comment Share on other sites More sharing options...
Guest 280ZForce Posted May 3, 2007 Share Posted May 3, 2007 you may actually want to upgrade to the larger BMC while your at it since you've upgraded the brakes if you havent already. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 3, 2007 Share Posted May 3, 2007 Go through and check all your connections too. I once had this problem when bleeding a friends newly rebuilt 510. We bled the master and all the wheels several times before we found that one of the SS brake lines was finger tight. It wasn't leaking fluid out, but apparently it was sucking air in. My guess is that it is probably the master though. Also, if you use a tube from the bleeder back into the reservoir push the pedal down SLOWLY! If you slam the pedal down you'll put lots of bubbles into the master, which in subsequent bleeds will put that air back into the lines again. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted May 3, 2007 Author Share Posted May 3, 2007 I just finished bleeding the master, I bled one "reservoir" at a time, slowly. the pedal did get a bit firmer, but still slides to the ground. if I pump it quickly, I get a firm pedal, if I push slowly it goes to the ground and is soft. I attached a hose to the MC bleeder, ran the tube into the reservoir and made sure it was submurged under the fluid and I pumped slowly about 10-15 times about. After bleeding the MC should I then go back to all four corners?! Quote Link to comment Share on other sites More sharing options...
evildky Posted May 3, 2007 Share Posted May 3, 2007 when bleeding the calipers is the dleeder at the highest point of the caliper? I had trouble with my old z31's bleeders not quite at the high point, I pivoted them out and stuck a piece of wood in place fo the rotor and bled them, got that little pocket of air out Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 3, 2007 Share Posted May 3, 2007 if I pump it quickly, I get a firm pedal, if I push slowly it goes to the ground and is soft. This is exactly how you test a master cylinder. If slow pressure makes it go to the floor, it's bad. It probably had some crap way down in the cylinder where it normally didn't harm anything, but when you bled the system you pushed the seal through the muck and damaged it. I think you need a new master at this point. I have a genuine Nissan master (not a rebuild) for a 280ZX that I used on my car. It was in great shape when I removed it. If you're interested, PM me about it. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted May 3, 2007 Share Posted May 3, 2007 Ryan, if the calipers were dry before you put them in, you might remove the 2 mounting bolts and kind of move/shake the caliper around. Do this with the brake lines attached. You're trying to dislodge any air that's trapped inside the body of the caliper. There was a thread here last year about a guy who experienced what you are, and that was how he finally fixed it. The theory was that there was air trapped inside the caliper where the brake fluid hadn't fully "wetted" (if that's a word) the interior of the caliper. When I put mine on, I did this from the start and never had any issues with bleeding. I'm not saying my one data point proves it, just suggesting it's a quick and easy thing to do before you tear into replacing things. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted May 4, 2007 Share Posted May 4, 2007 I actually got a bad new MC one time, so don't discount this option. Quote Link to comment Share on other sites More sharing options...
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