tried to bleed brakes 6H later still no luck

[gacksen]

spent two hours reading several posts but could not find any answer

changed the rear rubber hoses to braided ones the last days and tried to bleed the system today.
first bleed the tandem master with rubber hoses attached to the bleed screws into the reservoirs
until no air came out. have speed bleeders all around so started on the rear passenger side first.
then rear driver, passenger front and driver front side until no air came out of all the calipers just plain fluid.
have willwood fronts and started to bleed the inner valve of the caliper first. checked for
leakes of any kind and there seem to be none. system is not losing and fluid.

checked for any wilwood proportioning valve but there seems to be none in sight.

when i press the pedal it is full soft and brake light goes on. if i press it again say within 1 second
and pump the brakes will get pressure on the pedal and it feels normal but after waiting 5 seconds
pressure is gone and i would have to pump it again.

what i noticed with reservoir caps off the fluid in the reservoir tank for the front brakes stays level while
pressing the pedal. the reservoir tank of the rear brakes drops fluid down around 1/4 inch while pressing.
after some seconds fuild level will go up again. i guess it corresponding with the brake pressure.

is there and secret trick as i don´t know what to do else ?

[Chris_Hamilton]

Are you sure your Master Cylinder is good? I had a rollback truck once where the master cylinder went bad, it had brakes (pressure) but the pedal would go soft in a couple of seconds. Basically you could stop but it would not hold. Sounds like yours is doing something similar. If you've bleed them and cannot find any evidence of leaks,  I'm 99% certain it's your Master Cylinder.

[RebekahsZ]

Call me at 256-366-4685 tonight or tomorrow and I will try to help. I've been where you are. Put down the hammer.

[socorob]

Have you tried to gravity bleed them to see how much comes through?

[RebekahsZ]

Your symptoms all say you got a lotta air in the system. Great description.

 

A couple things (Im up early with a migraine).

 

Start with bleeding the master cylinder. You'll never get pressure to bleed the wheels if the master is full of air. Once you have bled enough to have clean fluid in the system (and i mean totally clean, and if you are going no-shit road racing you might not want to do this), conserve fluid by recirculating it. Run a clear plastic tube from the bleed nipple at the master cyl back into the reservoir. Keep the tube under fluid and crack the bleeder just enough to let fluid flow. With the tube under fluid, you should be able to get your assistant to pump repeatedly without you having to open and close in a coordinated fashion like you will for the wheel cylinders. Get 100% no bubbles at the master at each bleeder separately. Them tighten up the bleeders and have a beer and kiss your assistant (or knuckle bump if you find that more appropriate). Remove the clear plastic hoses, clean up all the drops and places where you flung brake fluid on your $15,000 paint job. Do all your bleeding with the little baskets in the reservoirs-fluid will shoot out of the bottom orifice and ruin your new paint job if you don't. Those baskets have a purpose beyond catching dust and debris. Brake fluid won't blind you if it gets in your eye, and I have ingested quite a bit without too much brain damage (I swear those voices are real, even though nobody else hears them)!

Edited November 2, 2014 by RebekahsZ

[RebekahsZ]

It doesn't matter if you bleed the front wheels first or the back-the circuits are independent and have their own reservoirs. Check your reservoir FREQUENTLY or you will have to start back over bleeding at the master cyl. If you have two sons, or two girlfriends, station one at the reservoir to tell you when it is getting low, but you add fluid yourself so you don't have to kill your son or break up with your girlfriend when she spills brake fluid on your $15,000 paint job. I have speed bleeders in all my wheel cylinders, but it is just for insurance. I still open and close the nipples old-school style so that a speed bleeder doesn't ruin my day, night, or week.

 

For the fronts: Wilwood brakes on the front are mounted such that the air bleed nipple is NOT AT THE TOP! So, you will never get them bled as they hang when they are mounted. Air rises. This is the greatest obstacle to any bleeding operation. It fights those of us with internal clutch hydraulics like a MF-er. You gotta position the component such that the nipple is at the very top. For your Wilwoods, this means unbolting them and holding them in the proper orientation. I have a block of scrap wood that I have cut to the same thickness as my rotor, which I shove between the pads to simulate the rotor so that it is easy to put the caliper back on when I'm finished bleeding. It is easy to run out of hands during Wilwood bleeding, so get organized before you start. If you use a piece of wood like I have described, you may be able to leave the lower caliper mounting bolt in and just rotate the caliper up to get the air hole to a vertical position, then push the wooden block in at the top. Once you have the caliper turned up, bleeding will go fast, but these big calipers hold a lot of fluid/air, so be patient. The willwood bleeder uses a 1/4" wrench-use the box end. After you have bled the upper outer bleeder, bleed the upper inner bleeder. Don't crack the lower bleeders. You WILL spill, so have a can of brake cleaner and paper towels right beside you. To conserve fluid, if your fluid looks as good in your CLEAN catch can, you can put it back into your reservoir and recirculate it. Don't do that if you are going to be racing your Z in NASCAR, but for a street car, you should be fine. Once you have the front free of air, bolt it back together and move to the rear.

[RebekahsZ]

To help with the rears, you gotta tell me what kinda brakes you got back there-they all have different problems. Stock Z brakes have the bleeders at the top so they are easiest, but the big hassle of most of the "upgrade" kits is that the bleeders are oriented wrong and a big air bubble just sorta hangs out. You gotta get the bleeder to the top. And I still recommend that you use an assistant to do coordinated pumping so that the bleeder is open on down-stoke and closed on up-stroke. The only thing keeping air from coming around the threads of a speed bleeder is a little caulk. Also, on stock rears, you gotta use the hand brake a bunch of times to adjust the shoes to be in close proximity to the drums. A hole drilled in the face of the drum lets you do this manually (a trick from johnc). A little rise and fall in the reservoir is normal (barely detectable), but a lot of fluid movement means air in the system, and possibly excess movement if components (like the rear shoes). But, adjusting the rears would be the very last thing I would do after the system is free of air.

Edited November 2, 2014 by RebekahsZ

[TimO]

Nice write up!

[gacksen]

first of all absolutely great write up !

 

after 3 hours i skipped it for today. what i did had been the following :

 

1. switched back to the old rubber hoses on the rears just in case.

 

2. bled the master. first reservoir next to booster then the front one. clear hose from bleeder into reservoir. bleeder maybe 1/4 turn open. both reservoirs no bubbles at all.

    unknown factor is the bleeder as i did it by myself as girlfriend motiviation had been soso means kept pumping the pedal for some time. don´t think the bleeder will suck

    in air in the thread area but of course can´t tell for sure.

 

3. put the car on 4 jacks and for better access. started rear right same thing 1/4 turn speedbleeder open with clear hose in fluid canister.kept pushing the padal for 15x times.

    reservoir level then had been about 1/3. refilled the reservoir of rear brakes and repeated the process. pulled the handbrake some times but didn´t make a difference.

    unknown factor same as above would be the thread of the speedbleeder as i did it alone. don´t think it sucks air from the thread as the had been no fluid in the thread area.

 

4. repeated the steps on all 4x calipers twice.

 

    conclusion in the case nothing has changed at all. front reservoir for the rear brakes keeps on moving while fluid level of the fronts stays level.

 

    As the car had been jacked up anyway and i had some time tried the following :

 

1. connected clear hose to fron´t left caliper and rear left caliper. opened the bleeder 1/4 turn and started pumping. of course fluid level will drop differently i guess

    due to the brake balance of front and rears so front reservoir will be low on fluid earlier compared to the rears. thought maybe there is something blocked

    due to the pressure imbalance but it does not seem so.

 

made a picture of my front and rear calipers and can tell you...... brake fluid is the same hazzle as graphite grease

two hours had passed and still no success on the brakes so i stared looking and found an old pressure bleeder that will be connected

to a spare tire. when taking a look to all those brake lines espcially the rear one they are above the bleeder. as the pressure bleeder

was meant to be used for reservoirs with a thread on it and those in the car doesnt have one had to use a different construction.

checked the tire pressure and it had been 1.4 bar on the spare wheel. so searched for some clamps to get it kind of fixed on top but

wasn´t succesfull. ended up with big cable ties and i guess you know the rest of the story once pressure was on

 

after cleaning up the mess and thinking about what had been done in the past on the car. was in the workshop for new wheelbaerings

and they bleed the brakes without any problems. changed springs on the front dampers before that and drove the car to them with

brakes no bleeded they managed to get it done.

 

 

 

i guess those are the maxima calipers ?

 

maybe just more pressure of an air pressure bleeders is needed to get rid of the air trapped in the rears ?

[Miles]

In the future:

 

Note that the bleed nipple on the rear caliper (Maxima or 240SX?) is not vertical. 

 

Unbolt the caliper, leaving the hose connected,  and place a block about the thickness of the rotor between the pads. You do not want the pistons to blow out of the caliper.  

 

While holding the caliper so that the nipple is pointing up have your assistant pump the brakes. Rotate the caliper in various orientations to free up trapped air bubbles so they move towards the nipple. Repeat several times.

 

Also, installing  speed bleeders on the MC makes bleeding easier.

Edited November 2, 2014 by Miles

[johnc]

when i press the pedal it is full soft and brake light goes on.

 

 

The brake pressure switch is tripped and needs to be reset.  You have to thoroughly gravity bleed the brakes and get fluid to all four corners before pushing on the brake pedal.  If you don't, the difference in brake pressure front to rear causes the switch to trip and block off brake fluid flow to either the front or rear depending on which end has the lowest pressure (most likely the rear).

 

FYI... throw away the speed bleeders.  The exacerbate the problem you're having.  You have to get the front and rear hydraulics full of fluid without touching the brake pedal and speedbleeders keep that from happening.

[gacksen]

during the week will have some spare time to give it another go. will try to gravity bleed the brakes first and get the claipers on the rear off.

also friend of mine will lend me his workshop pressure bleeder and if more pressure can´t sort this thing out i don´t know

 

everytime the old story men vs machine but i know machine will lose this time

[NewZed]

To Miles's point, also mentioned by RebekahsZ:

[Miles]

Buy one of these with the generic adaptor fitting:  http://www.motiveproducts.com/

 

The Motive bleeder is the next best thing to gravity feed and it makes brake repair a one man operation. Makes it easy to bleed those Maxima or 240SX calipers where the bleed screw is not vertical.

 

Brake Differential Pressure Safety Switch: See pictures. The brake switch has a piston that shuttles to the low side of the brake system if there is a leak in the front or rear brake circuits. As the piston moves towards the low pressure side it makes contact with the wire that turns on the brake failure light.  I took mine appart and it appears that the piston will return to the central position once pressure is equal for the front and rear brake circuits. I found no mechanism that locks the piston in the rear or front brake circuit position.  If the piston/cylinder is corroded,  then the piston may stick in the bore and not return to the center position. My switch was badly corroded inside so I removed it and replumbed the lines to the master cylinder. Do not "gut" the brake switch. If you do you will tie the front and rear brake circuits together. Most likley, once you have all of the air out of the brake system the brake switch will not be an issue

 

Again, bench bleed the master cylinder until there are zero bubbles.  When you see no bubbles let the MC sit for awhile to allow small bubbles to gather and then pump the piston and bleed a few more times. 

 

Be methodical. Start with the MC and work each caliper until there is no air.

Edited November 3, 2014 by Miles

[RebekahsZ]

Johnc, how do I gravity bleed without getting brake fluid EVERYWHERE? And I mean everywhere-on my new pads, rotors, all inside the calipers, floor, etc? I have to be really careful when manually bleeding with a clear tube that always ties to pop off, and I still make a little mess.

 

Marry the first girl that still loves you after bleeding brakes. True test of character and compatability. I don't know why. All we ask is for her to sit on her ass and move her foot when we tell her to. Don't know why this is such a challenge to all relationships.

[gacksen]

To Miles's point, also mentioned by RebekahsZ:

could be the cause. hopefully with enough pressure this should be sorted. don´t think the shop i had it in that replaced the rear wheel bearings changed the position of the calipers.

 

my friend will lend me something like this and hopefully i can make one of those adaptors fit the reservoir properly.

 

[johnc]

I have to be really careful when manually bleeding with a clear tube that always ties to pop off, and I still make a little mess. 

 

 

Buy the correct size clear plastic tube.

[RebekahsZ]

Ouch

[socorob]

Ive always just used 4 pieces of small clear tubing going into a cup at each wheel. I did my car by myself and didn't even have to pump the pedal. Just barely crack the bleeders and go work on something else for awhile. This os assuming all your bleeders are in the highest location.

[RPMS]

I can't tell you how much easier it is to pressure- (or vacuum-) bleed the system. Sooo nice to not have to go through the "Push....release....push...release..." rigamarole.