Brake bleeding problem!!!

[elwood]

I just bled the brakes, now the pedal goes to the floor and there is a clicking noise comming from the front of the truck every time I apply the brakes in the driveway. They won't even stop the truck! What is the proper way of bleeding the brakes, maybe I'm doing it wrong. I have tried bleeding them like 4 times in a row, I can't get the pedal to come up! I need the truck for work so, I need to figure this out quick!

Please help!


Thanks,

Elwood

[Slonaker]

Maybe this will help?

Slonaker

[Grim Reaper]

Originally posted by Slonaker
Maybe this will help?

Slonaker

That is one of the better set of instructions I have read.

Here is a couple more tips. The old farce about go from the wheel that is farthest needs to be tossed out the window. Do either rear then the other. Then driverside front. If you look at the Combination valve the driverside front line is to the top outlet. We all know that air rises in fluid. Well if you try to do the passenger side first then chances are you going to have to do it a second time after the drivers side. It will get some air in it as you pump up to bleed.

Try gravity bleeding the rears first. To do that just top off the resivior. crack open the bleeders and let it run till the resivior is low. The way the brake systme is designed is in the Combination valve (CV) it delays the front brakes till the rears buid about 100psi of pressure. It does that because the rears don't react as fast as the fronts. So basiclly if you don't have any rear pressure you have a hard time getting front.

Now if this system was allowed to run dry you may have air trapped in the rear circuit in the combination valve. If you look at the valve the outlet to the rears is at the bottom and the inlet is in the top. It's a booger to get the air out.

To bleed that CV make sure the reservior is full. Loosen the inlet line for the rear circuit a few turns till it's leaking. Tap on the CV with a wrench lightly to dislodge any air bubbles. Retighten the Line before you run it out of fluid.

I figured that one out after doing a rear disc conversion where I modified the CV to disable the proportining valve to run a manualy adjustable valve. Could not get that booger to bleed for nothing till I did that.

My buddy that is a Pro wrench has a trick on stuborn systems. He modifies a Master cyclinder cover and puts an air fitting in it. THen he pulls about 10hg of vacuum on the system and lets it sit for a few hours. The vacuum will pull all the air back up into the reservior.

I haven't tried this trick yet but I have done something simular when I was in the specialty printing buisness. We made jigs to hold products we were printing on. The resin stuff we were using to cast with you had to get the air out or it would goof up. We used a pressure cooker and a vac pump. It would pull every bubble out of that stuff. Same principle here.

[elwood]

I have tried all that stuff, no change. I figured it might be the master cylinder, replaced it, now one of the fittings on it leaks. I'm screwed. Just did brakes all around. Can't figure it out.

[1FaastC10]

Originally posted by elwood
now one of the fittings on it leaks.

that's likely one of your problems. if fluid can get out, its almost 100% that air can get back in. air = no/low brake pedal

[swervin ervin]

Just asking, but you did bench bleed the master cylinder, right? Did you try tightening the fitting just a tad more? You might have cross threaded it. Try taking it back out and see what's going on. May also be a piece of metal or something between the seat and tubing. If all else fails, you could reflare the tubing or replace the piece. If you decide to reflare, it has be a double flare.

[elwood]

I bench bled it. Tightened it, made sure there were no objects holding the fitting from being tight. Checked and rechecked. The master cylinder is going back tomorrow.

[GMC JUNKIE TOO]

You might look into getting a miti-vac I got mine at auto zone its awsome it has a canister and a hand pump with a guage. open the bleeder and pump away. I used it today on my friends belair we put disc brakes on it and it took a while to pull the air out, but it is definatley worth the price.

[elwood]

Hmm... I might have to give that a try. I put another master cylinder on there, no leak. But I still cant get the pedal to come up. I might try a booster.

[RussTburb]

might be worth pulling the front wheels off and check while some one is hitting the brakes. if the caliper is crooked or the piston is cocked all kinds of crazy things can happen. Also have had the rear shoes a little off or stuck on the backing plate causing the wheel cylinders to never engage rear shoes so no pressure can build. just trying to help! or you may want to take to a shop and have them line clamp it to see were the problem is. good luck!

[Grim Reaper]

Originally posted by elwood
Hmm... I might have to give that a try. I put another master cylinder on there, no leak. But I still cant get the pedal to come up. I might try a booster.

Don't waste you money on a booster. If the peddle softens up when you start the truck and your not hearing a hissing noise from it when youapply and hold the brakes then there is nothing wrong with it.


I have the might vack also. It works good but I have had problemss bleeding alone because of the hold off valve in the CV.

Did you try gravity bleeding it?

[elwood]

What's up with this valve everyone is talking about?

[GMC JUNKIE TOO]

Its on the front of the prop valve in needs to be pushed in while youre bleeding.

[swervin ervin]

I always put a piece of tape on the pin on the proportioning valve to hold it in while bleeding. It doesn't take any pressure to hold it in. I found out a long time ago if the brakes are tough to bleed, this might be the cause.

[elwood]

Might have to give that a shot...

Thanks!