Bleeding Brakes

[tony1307]

OK.. I really am not as dumb as this may sound.... but I simply cannot get my brakes to pump up. 94 Ranger 4x4. I replaced the front calipers and when we went to bleed the system, the bleeder screws on the rear were a PITA. One stripped and the other sheered off. So I bought 2 new wheel cylnders. Well, we went thru and bled them RR LR RF LF in order and they would not pump up. I got a lot of air outta the RF, but that's about it. We tried to cheat and we put a bottle of brake fluid at each wheel, opened all 4 bleeders and started pumping. Making sure the MC stayed full of course. Then we closed the bleedes, and bled the system the normal way. It still won't pump up. GRRRRR

Help?!?!? :shock:

[mattadams]

hmm... just a thought, when you pressed on the brake, could you tell if it was compressing the pistons at all? Sounds to me like either bad brake line (clogged?) or a bad caliper...

[BluOval]

I don't mean to insult your intellegence but how are you bleeding your brakes? Gravity or vacuum? If you are using a vacuum pump on the cylinders you shouldn't be running into any problem. But from the sounds of it you are gravity bleeding. Take these steps and you should recover your pressure. This procedure takes 2 people to do.

1) person 1 stays inside to operate the brake pedal, person 2 does the bleeding.

2) person 2, starts at the 1st cylinder and has person 1 pump the brake pedal a few times and on the last pump holds the pedal to the floor.

3) person 2 opens the bleeder screw, bleeds the air and fluid and then shuts the bleeder screw. Have person 1 release the brake pedal. repeat step 2 & 3 until all air is evacuated.

4) repeat steps 2 & 3 on all cylinders and make sure your master cylinder stays full or you WILL be starting over from scratch.

If you are bleeding in this manner then you have a bad master cylinder.

[tony1307]

Well. we were using the normal way with 1 guy in the truck, one guy at the wheels. I have a bleeder kit that has a small bottle, and a line to the bleeder screw. and a magnet to hold the bottle above the bleeder to help the air go away from the cylinder. We did it in RR LR RF LF order, and it did not help. Now, I am going to lean away from the thoughts of a bad master cylinder as the brkaes were fine before. I rebuilt everything on my steering, and since we had to pull the calipers off to get the steering knuckle off, I figured we might as well put brand new ones on. So the lines and the Master were fine before.

[mattadams]

my vote is either with the caliper itself, or the caliper connection to the line, but Im not really certain. If it wasn't a Ranger I'd say I've got some calipers for you to try.

[clavos]

You say you got air out of the RF, and nothing out of the others? The problem could be in the lines (clog, pinch, etc.). If you have a vacuum pump that may create enough pressure to clear it. I had a similar problem on my Mercedes and ended up at the shop. They hooked it up to a high pressure bleeder and took about 45 psi to clear the blockage.

[tony1307]

We got air out of all 4 corners. It just seemed we got more outta the RF. We worked on it some more today. A friend of mine tried to help me out today. We went thru the same procedure as yesterday. No luck. He thought it was the Master Cylinder, and I told him it couldn't be, as it worked fine prior to replcing the calipers. We only replaced the calipers cuz they were already off to do the balljoints. So now it has 2 new front calipers, 2 new rear wheel cylinders, and a new Master Cylinder. We verified all the lines were tight. We bled the MC prior to hooking the lines up to it. I went to ALLDATA and they say that since it has Rear ABS, I need a special tool to bleed the RABS valve. Grrrr.

[Burg460]

OK, question..?

Did you put a new master cylinder in also??

If yes, did you bench bleed the new master cylinder? If you did NOT bench bleed the new master cylinder then I am about 95% sure that is your problem.

Only other thing I can think of is to check the pedal assembly under the dash and make sure the rod is pushing the master cylinder.

I also know that some vehicles that have ABS have to be bled a certain way because of the ABS motors and/or you have to have a scanner for the computer. If you don't bleed them the way the manufacturer says then that can also cause a problem. My .02 cents.

[tony1307]

Yes. It has a new Master Cylinder now too. Yes. It was bled prior to hooking the lines up to it. I went thru it all again today. 3 times. I even hooked up my little hand held vacuum bleeder. When we were all done it was the same result. Pedal goes straight to the floor.

[BluOval]

I really don't know ABS systems all that well but you say yours has ABS, have you tried bleeding the brakes with the ignition ON? This may be a stupid ??? but worth a shot.

[tony1307]

Yep.. even tried it with the damn thing running. :)


I went to the ford dealership and spoke to one of the service techs. He has no ideas either. He does not know of any special tool that is used to bleed the RABS valve. I am at a loss.

[Mind_Boggler]

hmmm Possibly a loose connection, or a bad line? only thing that I noticed that could be a problem, I noticed that you started w/ the RR. I don't know how your truck is set up exactly, but in my Toyota when I had to bleed the brakes, I had to start with the LR. This was because the line for rear brakes ran down the right side of the truck, making the LR brake the farthest from the Master cylinder by length of the brake lines. Maybe that line in your truck runs down the left side though, in which case I just wasted a lot of time typing this. lmao Anyway, I just thought that it might help.

~~Devin

PS- :idea: this will be a pain in the @*#, but it is possible that the new master cylinder is bad, so as a last resort, you may have to exchange it.

[mattadams]

My vote still goes to bad line or something... I like Niels idea of trying to do a pressure flush or something.

[tony1307]

well...

My lines do go down the left side, so RR is the farthest away.


I rechecked all of my fittings and everything it tight. I would tend not to believe it is a bad line as the brakes worked great before. There was no brake problem at all, we simply replaced the calipers cuz they were off at the time. The only reason I replaced the rear wheel cylinders, is cuz the bleeder screw sheared off on one side, and stripped on the other.

Tomorrow I am going to buy two little brass plugs. I will take the line to the rears off the Master, and plug it. Then I will pump it up with just the fronts, and see what happens. If that work good, I know the issue is in the rears. And vice versa. If the problem is in the rears, I will unhook the lines to and from the RABS valve. I will bypass the valve by running the lines around it. Then, I will bleed the system again. If it pumps up fine after that, I have a bad RABS valve.

[mattadams]

ok heres a thought no one has mentioned yet... you say you replaced the caliper, does your caliper have the single bolt holding it to the caliper that is "hollow" to allow brake fluid to pass through? Did the new calipers come with a new bolt like this or did it use the same factory bolt? I wonder if that bolt was not lined up or malfunctioning or something, that could cause a problem too.

[BluOval]

Did you accidently run the MC dry, if you did then you need to bench bleed it again. I think it's the MC because even if you had air in the lines then you should still be able to build up a little line pressure. Without looking at it I would say your MC has gone bad. Do you still have the old calipers and wheel cylinders, if so put them back on and see if you run into the same problems

[tony1307]

we have not let the new master cylinder run dry. And, we have bench bled it twice. It bleeds ok. I do not have the old calipers, as I turned them in for the replacements. As for the old wheel cylinders, I tossed them. One had a stipped bleeder screw, and the other had the bleeder sheared off. I could have saved them, and just used a screw extractor, I know. But for 12 bucks for new ones, it was not worth it.

And, the calipers do have the hole down the middle.


It does build pressure. You can pump it up as long as the truck is not running. The, you let it set for a minute or so, and it needs pumped again.

[BluOval]

This is my absolute last question: Which way are the bleeder nipples pointing? Up or Down?

[tony1307]

which way are they pointing? not sure what you mean.

The rear wheel cylinders only mount one way, the bleeders point straight out the back of the backing plate. They are on the top side of the cylinder, above the rear brake line.

The bleeders for the calipers are on the side of the caliper facing the rear of the truck. Above the brake lines, and they go straight out as well.

[BluOval]

on the calipers?

[BluOval]

so the caliper nipples are on the top of the caliper

[tony1307]

they are not on top. they come out at like "9 o'clock"

[BluOval]

HMMMM, must be a Ranger thing because all the calipers I've seen have the nipple on the top of the caliper so when there is air in them it goes up and out. I still think there is air in the system somewhere. Try bleeding the calipers off the rotors and point the nipple to the 12 o'clock position and let that air rise to the top. put something between the pads so they don't compress. If you are getting some pressure and then it goes away, that sounds like air to me.

[tony1307]

Yea... I am completely convinced that air is still my problem. I am going to try to bypass the Rear ABS valve first though. It is the only place I can figure where air could still be. If I can't fix it by the weekend, I am gonna offer up some cash to anyone who can fix it. :lol:

[BluOval]

Drive it over to my place, just don't hit any red lights, LOL Man I wish I could help but I'm extremely busy this weekend.

[tony1307]

well. I figure if I buy the little brass plug, and disc the rear brake line. I can plug it off at the master, bleed just the fronts. If everything is ok, then I KNOW the problem is the rear cylinders, or the RABS valve. Plus, since the rears only do 20% of the braking, if I have just the fronts it is technically driveable. Enough maybe to get it somewhere and let someone else have a crack at it. But, I can unscrew the lines from the RABS valve, and bypass it by making a connector to hook the two lines together. If the rears bleed out and work ok, then it HAS to be the RABS valve. If not, then I am clueless at that point.

I appreciate the offer though.. thanks

[tony1307]

update.


Unhooked the rear brake line from the Master. Screwed ina plug where that line used to be. Got in Ranger. Brake pedal was hard and firm. Started him up, hit the brakes. Stayed right at the top. Back him in and out of the driveay a few times. Front brakes working great. Now I need to bypass the RABS valve, and see if the rears work.

[tony1307]

Yes. It's true. I have brakes again. You all know the story, but in addition to everything else I replaced, I also replaced the RABS valve under the truck, on the frame rail. For the hell of it, I also replaced the rear brake hardware kit, and adjusters. I bought 25 ft of aquarium tubing from PetSmart, and bled the brakes in an odd fashion. BUT.... it worked.
I hooked the line up to the each bleeder (one at a time) , and ran the other end of the line up to the Master Cylinder. With the truck running, we pumped the brakes like 30-45 times letting the fluid cycle thru the entire system and out along the tubing, and back into MC. It worked. I drove Ranger again today and it felt great!!!

Thanks to EVERYONE who contributed an idea.....


:lol:

[mattadams]

Wow thats a wild idea, I might have to try that next time, LOL. Glad to hear everything is working again.

[crazy rob]

I'll probably have to enlist some of you to help me with my brakes when I go to put on the braided stainless steel hoses i recently recieved that will help accomidated for the lift and hopefully one day, disc brakes.