S13_Hatch_Boii

So i have a 1990 240sx no abs and it had been leaking brake fluid from where i can only assume was the master because it would leave a big ol stain on the driver way right under it. Well this last week it had been sitting and when i went to go drive it i checked for fluid it was near empty so i filled it, went to start it and there was no brakes, pedal went straight to the floor. I left it alone and thought maybe it just needed a bleed. I came back the next day and bled it RR, LR, RF, LF and still no brakes. Pedal felt almost "springy" there was no resistance when it was off and when it was on it was soft, i would pump it while it was on and it would get a little stiff but go soft right after. The weird thing is that only the front calipers have air the rears had no air what so ever. I was like well maybe my brake master finally gave a poop on my so i replaced it, bench bled before throwing it on and then started bleeding the brakes again this time LR, RR, RF, LF and still the same springy pedal and again only air in the front calipers but this time it was much less air. So right now im not sure what it could be.

mechanicalmoron

Uhh you can't find the peeling paint and glycol all over the leak?

Bleed it better, obviously.

There are two internal cylinders, one for the front, one for the rear - it only dropped down low enough to bleed out the front the first time, most likely.

If you can't bleed it, you may need to bench bleed again - maybe there's a problem with your bleeding technique? The bleeder needs to be closed while the pedal rises, you can use a friend or put a prop between the seat and the pedal, then go open and close the bleeder. Or you can vacuum bleed it, or reverse bleed it, with a large plastic syringe stuck on your bleeder hose. (of course, reverse bleeding means you will push any crud into the master, so do it with some caution, it's a somewhat better idea to pull the crud on thru from the dirtiest end).

For bench bleeding,, make sure the hoses you have stuck on the fittings are dipping back into the reservoir, since you don't have a bleeder to close to keep it from sucking air backwards. And take full slow strokes, fast ones just break up and bounce around the bubbles.

S13_Hatch_Boii

Thats what i did had a friend pump the brakes, hold , let the fluid out then close and repeat. same thing with the brake master, had the lines going back into the reservoir and slow full strokes. Would it be affected in im doing it on the street because the street is on a pretty big hill?

mechanicalmoron

Shouldn't matter.

Find the puddles. (and I wasn't being so serious, I know it can be hard, actually lost brakes on my truck today, and I thought she was good this time) If it's your master, the booster and firewall will have peeling paint, and there may be a drip in the car, or fluid in the booster. If it's a wheel cylinder, there will probably be crud on the inside of a wheel, and if it goes on a while it'll peel the clear coat, too. The drip generally comes down the inside of the tire, and may have radial stain lines where the drips get thrown off the wheel as you take off.

I don't like 2 man bleeding with almost anyone in the world, it can be fast and smooth, but working alone is priceless, you are the only one responsible for the quality of your work that way, there are no unknown pedal flutters or anything to take into account, nobody to blame. Try blocking the pedal down with something against the seat (a board or whatever, but the absolute best is a telescoping hood prop tool, since you can push the pedal and extend it to fit exactly for each stroke), and a few strokes on each caliper should at least give you some pedal, if the master was bled an everything is working. Going around a few times can be helpful.

NashT

If the leak was at your booster then it was your master cylinder undoubtedly.

Those common brake bleeders suck, harbor freight has a pneumatic vac brake bleeder for $40 if you have an air compressor. Those work awesome and will get every bit of air out of your system.

Another technique you can use is connect a hose to the bleeder and put it in a bottle with brake fluid and pump the brakes.

NashT

Also, yes always start bleeding with the farthest bleeder first and end at the closet to the master cylinder.

So Rear Right, rear left, front right, then front left

S13_Hatch_Boii

So i actually did that today, i bought that harbor freight bleeder and used the air compressor and i eventually got all the air out and brakes started to feel normal. But when i want to drive it it lost the brakes again, and jt was leaking, checked under the hood and the plug in between the two front lines popped out and was shooting fluid through there now. So im kinda at square 1 again.

mechanicalmoron

well the good news is, when you actually fix the brakes, the procedure to bleed them will be the same. It will also be a lot easier, considering you were bleeding the unbleedable.

S13_Hatch_Boii

Should i replace the master again and try again since i lost that little plug?

mechanicalmoron

I have no idea what plug you mean, but obviously, take it off the old one.

What are you asking, if you should delete your brakes entirely, or fix them?

S13_Hatch_Boii

Nah i tried that but that plug flew off too and no how am i gonna delete brakes? I meant should i replace the master cylinder again?

mechanicalmoron

The FSM is on NICO.

It'll tell you every fucking thing you want to know. pretty sure it's got master cylinder rebuild diagrams, honing instructions, everything. Figure out why it's flying off and what it is.

mrmephistopheles

Replace your master. Buy an OEM one if you can afford it. Otherwise you're more likely to experience bullshit failures. Looks like you've got the process for bleeding down now, so beyond that you'll be set. Rinse all brake fluid from your paint extremely well to avoid paint damage.

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silverarrow27

Did you buy the wrong master cylinder and left the plastic plug in one of the holes?

I think pictures would do wonders for you on here since you can't explain or describe anything worth your life.

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1989 240sx XE|2002 Frontier SC CC LB 4wd|2011 Pathfinder LE V8 4wd