Empedocles99 Posted January 9, 2007 Share Posted January 9, 2007 So.. for the past two months, my rear control arms have been off the car, and the brake lines were just sort of hanging out, disconnected. This week, the brake lines were re-connected, and the suspension reassembled. My friend and I are using one of those 'one man' bleeder kits to remove the air that was introduced by disassembling everything. We got the air out of the rear calipers (took a little over 1/2 liter of brake fluid), but now we've moved to the front and while bleeding the right front alone, we've already gone through 1/2 liter of brake fluid and large air bubbles are still coming out. Does this seem excessive? How much should I go through before I become concerned that there is a problem (leak i guess?). Note that this is not exactly a Z, but a Nissan s12, but I'm assuming that most of the advice will carry over. - Chris Quote Link to comment Share on other sites More sharing options...
johnc Posted January 9, 2007 Share Posted January 9, 2007 Did the MC resiviors go dry? If so, you need to bleed the MC first before bleeding the lines. If not, check for fittings that might be a little loose letting air into the lines. Quote Link to comment Share on other sites More sharing options...
jt1 Posted January 9, 2007 Share Posted January 9, 2007 I've pretty much concluded a quart of fluid gives a good system flush, starting with a wet system with no air. With a dry system, 2 or 3 quarts would not be unreasonable. Like Johnc says, start with the MC first. Getting all the air out of a dry system usually takes several trips around the car. John Quote Link to comment Share on other sites More sharing options...
Empedocles99 Posted January 9, 2007 Author Share Posted January 9, 2007 Did the MC resiviors go dry? If so, you need to bleed the MC first before bleeding the lines. If not, check for fittings that might be a little loose letting air into the lines. I used a pump to pump the fluid out of the MC... the stuff that was in there is likely 20 years old, really nasty with little floaty bits in it. My hose was pretty big, so I don't think I let the air get down in to the lines, but maybe it got trapped in the MC somewhere. I'm gonna check and seal my fittings with teflon and start over with the MC. Thanks Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted January 9, 2007 Share Posted January 9, 2007 I used a pump to pump the fluid out of the MC... the stuff that was in there is likely 20 years old, really nasty with little floaty bits in it. My hose was pretty big, so I don't think I let the air get down in to the lines, but maybe it got trapped in the MC somewhere. I'm gonna check and seal my fittings with teflon and start over with the MC. Thanks No teflon. They are compression fittings. If the fluid is getting to the threads then they have already failed. The seal occurs where the tapered part hits the flare of the brake line/fitting. If you are still getting air after having flushed a half liter of fluid, then my guess is you have a loose fitting. Also, when you open the bleed valve, turn it back down with your fingers until it just starts to touch. That way air will not be sucked back in through the threads of the bleed valve. Quote Link to comment Share on other sites More sharing options...
ezzzzzzz Posted January 9, 2007 Share Posted January 9, 2007 I use speed bleeders as these make this job much quicker and easier. That said, if you're using the conventional bleed screws that is fine. Use a tight fitting hose long enough the sit in a collection bottle with 2" inches of brake fluid already in there. This will aid in determining if the air is bled and helps reduce air being drawn back into the caliper/wheel cylinder. Tighten everything down and pump the brakes. If there is a leak you should find it weeping at one or more connections. Never let the MC go empty once you've started the process. Lastly, if you haven't bled the MC properly then all else is wasted effort. Quote Link to comment Share on other sites More sharing options...
Empedocles99 Posted January 9, 2007 Author Share Posted January 9, 2007 I use speed bleeders as these make this job much quicker and easier. That said, if you're using the conventional bleed screws that is fine. Use a tight fitting hose long enough the sit in a collection bottle with 2" inches of brake fluid already in there. This will aid in determining if the air is bled and helps reduce air being drawn back into the caliper/wheel cylinder. Tighten everything down and pump the brakes. If there is a leak you should find it weeping at one or more connections. Never let the MC go empty once you've started the process. Lastly, if you haven't bled the MC properly then all else is wasted effort. Yeah, I guess if there is air in the MC, then its going to just fill the lines till I get it all out, oops. I'm using this thing to bleed: Powerbuilt Brake Bleeder Master Kit For bleeding of all types of automotive hydraulic cylinders by one person Features durable plastic bottle with magnetic clamp, tapered fittings that fit both bleed screws and master cylinder fittings, and 3 pieces of vinyl hose. I thought it had a check valve of some sort so that it wouldn't let air back in through the bleeder screw, but that might be incorrect. Thanks for the help. I'll be doubly sure to not loosen the bleeder too much when attempting again tonight. Quote Link to comment Share on other sites More sharing options...
Empedocles99 Posted January 10, 2007 Author Share Posted January 10, 2007 I guess theres a leak! I see fluid trailing down the brake booster where the master cylinder connects to it. A new master cylinder will fix this, yes? Also, someone told me I should bleed with the cap off the master so it doesn't pull air through gaskets... is this true? Thanks everyone for the help so far, the tip about not opening the bleeders too much helped a lot! - Chris Quote Link to comment Share on other sites More sharing options...
jt1 Posted January 10, 2007 Share Posted January 10, 2007 Yeah, you're going to need a new/rebuilt master cylinder. If it's leaking fluid out it's almost certainly getting air inside too. Leaving the caps off or loose is a good idea. John Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted January 10, 2007 Share Posted January 10, 2007 Are you sure it is leaking and you didn't just spill some fluid? Quote Link to comment Share on other sites More sharing options...
naviathan Posted January 10, 2007 Share Posted January 10, 2007 Are you sure it is leaking and you didn't just spill some fluid? Yeah, typically when it leaks between the MC and the BB it leaks into the BB and you end up with brake fluid in the vacuum line and intake. Quote Link to comment Share on other sites More sharing options...
Ferd/289 Posted January 10, 2007 Share Posted January 10, 2007 I usually perform a 'bench bleed' for the MC. Remove the MC and place in vice. Then use the MC rod itself to pump fluid through. THis way you test the MC for leaks and can see clearly what is happening. Use 3/8 clear tubing on the rest of the bleeders onece you re-install the MC with at leat an inch or two on the bottom of the vessel so air does not get sucked back in. Hope this helps Ferd Quote Link to comment Share on other sites More sharing options...
Empedocles99 Posted January 10, 2007 Author Share Posted January 10, 2007 Are you sure it is leaking and you didn't just spill some fluid? No, I'm not sure, but I don't think I spilled nearly that much fluid. And the cylinder itself is relatively dry, but the junction between the booster and the cylinder is not. Quote Link to comment Share on other sites More sharing options...
Empedocles99 Posted January 10, 2007 Author Share Posted January 10, 2007 Yeah, typically when it leaks between the MC and the BB it leaks into the BB and you end up with brake fluid in the vacuum line and intake. Should I try to clean out the booster to get the fluid out? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 10, 2007 Share Posted January 10, 2007 Should I try to clean out the booster to get the fluid out? Yes, definitely. It might very well be full up to the bottom of the master. Quote Link to comment Share on other sites More sharing options...
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