Brake bleeding problem (Solved)

[lee_ford]

Last week there was some brake fluid in the floor board below the brake petal. So today I installed a rebuilt master cylinder. It stops ok, but feels a little spongy. Rear brakes lock first under hard braking and fronts lock up in reverse, so I went to bleed the brakes. The front brakes will not bleed.

A little more info; it is a 69 with manual brakes. Not long after I got it, I replaced the rear slave cylinders. At that time I was able to bleed all four wheels.

Today, I removed the bleeders completely and put all my muscle into it. Nothing.

I guess one fix is to just replace the front slave cylinders, unless someone has an idea on what is going on here that is my next plan.

EDIT: I found the problem. My problem was not in the bleeders. This thread does contain tips to help someone whose front brakes do not work at all. If that is your issue then continue to read.

However, if the brakes work and the bleeders do not, then here is my final post on the matter.

Enjoy.

Well, I got the wheel cylinders changed out. I went ahead and got a spring set too. It needs new shoes and the drums turned, but that will have to wait. Brakes are working better now.

While doing so I realized how courteous you guys are. Had you guys not been so nice though and had the first question been different, we could have ended this two days ago.

I hesitate telling you what that first question should have been, but I know you guys spent time trying to help. So, here it is…

“Are you opening the brake bleeder or are you removing the king pin grease fitting?”

OK, it was dark, I was tired and I was feeling around and found something that felt right.

[Mach428]

You have to bleed the master cylinder before it will build pressure to send to the wheel cylinders. To do this, you need to purchase a master cylinder bleeder kit, which consists of two plastic fittings that screw into your MC where the brake lines go. The other end of the bleeder fittings looks like a vacuum hose fitting. There you mount two rubber lines and fill the MC with fluid. Run the other end of the rubber hoses back into the top of the MC and hold the ends BELOW the fluid level.

Then simply have someone gradually pump the brakes (easy) all the way to the floor. You will see bubbles in the fluid appear with each pump. When the bubbles are gone, so too is the air in the MC piston. Reconnect your brake lines and bleed each wheel cylinder starting at the RR, then LF, RF, LF.

Good luck!!

[Mach428]

Sorry I meant RR, LR, RF, LF. The object is to bleed the wheel cylinders farthest from the MC.

[lee_ford]

… fronts lock up in reverse, …

[Using the best diplomatic voice I have…]
I know what is involved in the replacement of a master cylinder. I did use bleeder tubes and everything seemed fine setting in the drive.

I KNOW there is pressure in the line and that the master cylinder is working right.

However, the brakes do feel JUST A TAD spongy. I went to bleed the brakes and the front ones will not bleed at all. No air, no fluid, no nothing. Again, the front brakes work. I can feel them when I am touching the drum and the wife presses the petal. And they lock up in reverse and do most of the stopping going forward.

Again, loosening or even removing the bleeders on the front brakes does nothing. This is my problem. I cannot bleed the front brakes.

[fordman]

it sounds like there is a blockage of soem sort in the front wheel cylinders. what the blockage is i dont know. it could be air it could be dirt. you can stick a pic in the bleeder hole to see if you can clear the blockage. if not you could get new front wheel cylinders.

[lee_ford]

A pick does nothing.

Looking back, since I only did the rears last time, I would not have needed and may not have bled the fronts. If so the PO may have rebuilt the fronts wrong. That is all I can come up with.

I think new wheel cylinders is my best bet at this point. When I get the old ones off, I’ll see if I can see what is going on.

I’m going out of town for a week or two, so when I get back and get it fixed I’ll report what I find.

[Wes]

the distribution block shuttle valve shifted. put the front bleed screws in snug down. Open a rear bleeder then step on the brake fairly hard. close the rear bleeder and attempt to bleed fronts again.

http://www.fordification.com/tech/image ... system.jpg item # 2b257

[fordman]

good call wes. i keep forgetting about that valve.

[lee_ford]

Wouldn't that prevent any pressure from getting to the front brakes?

[Wes]

I'm unsure what your question is asking. The valve has shuttled over to block the front brakes. By opening a rear bleeder the intention is allow the pressure drop on the rear brake side of the valve, in theory allowing the shuttle valve to return to neutral. Rust and dirt may interfere the free movement of the shuttle. This part is also called Pressure Differential Switch.

[lee_ford]

I guess I have more than one problem.

First is when opening the front bleeders it relieves no pressure although the brakes are applying which means there is pressure in the line.

Second is an imbalance in the front and rear brake pressure.

Thanks for the info and I will do the procedure for balancing the front and rear brakes when I can get the fronts to bleed.

Any thoughts on the first issue?

[Mach428]

If your brakes are being applied to the front (which it appears they are by your description of them locking up in reverse when the brakes are applied) there is obviously pressure being applied to the front wheel cylinders. Take the brake bleeder all the way out and then have someone slowly apply the brakes to see if you get fluid. The bleeder may be clogged.

[lee_ford]

Original post quote…

…Today, I removed the bleeders completely and put all my muscle into it. Nothing. …

… Take the brake bleeder all the way out and then have someone slowly apply the brakes to see if you get fluid. The bleeder may be clogged.

I thought of that and did that. I have had bleeders plugged before and fluid came out around the threads. This time I removed them completely and slowly applied a LOT of pressure.

Nothing came out so the blockage must be within the brake cylinder itself.

[Mach428]

One way to tell for sure is to loosen the brake hose that goes into the front wheel cylinder, then do the gradual pump test. I'm just thinking of the process of elimination to determine where you do and don't have pressure. There must be pressure in the line and the cylinder if your front brakes are working.

Failing that, I think you will have to dig into the front brakes and see what the inside of the wheel cylinders look like.

[lee_ford]

…I think you will have to dig into the front brakes and see what the inside of the wheel cylinders look like.

That is the plan from here. Got me bumfusseled.