To start this off, The dash brake light has been on since I bought the truck.

One day I had a tire split. So the next day i drove it (hoping to god it didnt pop) to work and put some tires on it. I noticed i had almost no brake pad and the fronts and my driver front rotor is horrible. But i got some tires that werent may-pops and i was good to go at that time, brakes still worked.

Then after they wore the rest of the way out i heard the all too familiar sound of metal grinding on metal and decided i was going to change my front brakes for now and then save up some money and change my back ones. So I did that, and it involved a broke caliper bolt (if anyone remembers that thread i finally got it out), a new caliper and a new flex line on the passenger side.

Got all that new stuff on there and bled the brakes, got some pressure and drove it. The first stop i came to i realized that when i hold my brakes the pedal will go to the floor and release. I bled them again, they had good pressure(brake fluid shot in my face).

Leak? No, cant find one. So i thought it was the seals inside of the master cylinder leaking. I changed it yesterday. Followed the instructions on bench bleeding, got that done and put the new (well remanufactured) one back on there. Had to go to work then when i got home didnt have anyone to help me bleed the brakes.

I also noticed that the brake failure light went off after changing the master cylinder. Do any of you guys think I may have some how reset the proportioning valve? By reading old posts it seems as if those are a bitch the reset.

So today i went out there with someone to help me. Started at the passenger rear. The pedal goes all the way to the floor easily with the truck off. Had him pump them up, still didnt build any pressure up but i figured i would loosen the bleeder screw and see if any fluid would even come out. Nope. So i figured maybe the proportioning valve was still cutting the rear brakes off and i tried bleeding the front brakes. Started at the passenger side and still couldnt build up any pressure. When i would loosen the bleeder screws the fluid would come out extremely slow. I tried a couple more times and decided i wasnt getting anywhere and would ask some people that know way more than I do their opinion.

So, can anyone give me a thought on this? I have no idea why there wouldnt be pressure building up in the front brakes if the proport. valve is blocking the rear off. And i dont know how i could have opened it back up except maybe when i changed the flex line on the front passenger side and lost the pressure to the fronts.\

Either way this truck is driving me crazy. No ride sucks really bad.

But thanks in advance.

 

Did you bleed both rear brakes? The proportioning valve should not cut off fluid to the rear brakes. Have you checked the lines for leaks or damage? If you can do it, you might want to consider changing the other caliper so they are done in a pair. Also check the rear brakes and wheel cylinders for leaks. Also, did your tire wrap around the rear axle when it split? I thought it had pinched the rear line you said (or am I thinking of a different post?)

 

Ive traced the lines and cant find a leak anywhere. The flex hose to the back brakes looks pretty rough. I will be changing that too. I plan on changing the other caliper when i can.

No the tread didnt come off. it just split in the middle of it really big

 

Sometimes you have to tap the master cylinder to get the proportioning valve to work right. My truck was doing excately what you said yours is doing and after a little tapping on the master cylinder with a rubber mallet it worked great.

 

Sometime brake bleeding ESPECIALLY when a new master cylinder is installed can be a little problematic. Sometimes even if you bench bleed the master correctly ... you still can get some air that is tough to get out.


Let me suggest a different method. This is the "Old Coke Bottle and hose" method.

You're gonna need some stuff:

A minimum of 1 Quart of brake fluid ... and maybe an extra pint.

About 16 inches of 1/8 inch vacuum line.

One empty Coke bottle. Or any CLEAR glass or plastic 16 oz. bottle or jar will do. Iced Tea? Gator Ade? It's got to be clear ... you have to be able to see the fluid in it.

An assistant ...


Please make sure the rear brakes are adjusted correctly. You won't be able to bleed ANYTHING is the rears are out of adjustment.

Please make sure you can open ALL the bleeders!

During the bleeding process ... make sure you KEEP THE LEVEL OF FLUID IN THE MASTER FROM DRAINING OUT!!! If you run the master dry ... you got to start all over again.

1. Put about 2 inches of brake fluid in the coke bottle.

2. Starting with the brake furthest from the master cyl (Right Rear) crawl under the truck ... open the bleeder ... slip one end of the hose over the bleeder ... and put the other end of the hose into the coke bottle ... so that the end of the hose in at least halfway in the fluid.

3. Tell your assistant to pump the brakes VERY SLOWLY ... making sure to go all the way to the floor ... and then let it come all the way to the top ... then pause for a moment or two ... and pump again. LEAVE THE BLEEDER OPEN WHILE YOUR ASSISTANT IS PUMPING. The brake fluid in the bottle will prevent you from sucking air back into the system.

4. Watch the fluid in the bottle ... after about 6 of so up and down's ... you should see bubbles coming out of the hose ... sometimes it comes out with a big burst ... so make sure the hose doesn't come off the bleeder.

5. after every TEN up and downs ... have your assistant check the fluid level in the Master ... and top it up. THIS IS VERY IMPORTANT!!!

6. Repeat the process until you get no bubbles ... and only clean clear fluid comes out of the hose.

7. When you have no more bubbles ... have your assistant hold the brakes to the floor ... remove the hose ... and tighten the bleeder.

Move on to the Left rear and repeat the process.

Then the Right Front ... and repeat the process ...

Last ... the left front.



As a safety feature modern brakes have a "split system" ... the thinking is ... if you lose system integrity in one part of the system... you still should have some pressure left for braking. Or so they tell me!

The Brake system warning light comes on when there is an imbalance of pressure in the hydraulic system ... you've lost pressure in the rear ... or in the fronts ... this causes a piston to shift in the sensor (aka proportioning valve) (it's located on the chassis down under the Power Booster ... its that thing with all the brake line and a couple of wires going to it.). If/when the piston shifts ... it bridges a couple of terminals and the dash warning light comes on.

When the brakes are bled properly ... and the system is "equal" ... the piston should "center" all by itself ... and the light will go out.


BTW #1. Sometimes tapping (not pounding) on the master cylinder or brake lines will get a stubborn air pocket to move. No hammer required ... just tapping with a wrench should do it. Feel free to tap on the proportioning valve also, if you'd like.

BTW #2. In 30 years of auto repair ... I have NEVER seen a "jammed" sensor (aka ... proportioning valve). I'm not saying it CAN'T happen. I just have never seen it.

BTW #3. Be thankful you don't have a problem bleeding the brakes on a Volvo 240. These things have THREE BLEEDERS on the front calipers ... and a VERY complicated bleeding procedure.

As many of them as I have worked on... I always had to bleed them ... WITH THE BOOK OPEN.


Please let us know how you make out.

 

One more thing ... I just re-read your initial post in this thread.

You replaced a front caliper ... and a front hose ... correct?

If memory serves me correctly ... the Ford's front brake hoses do NOT thread into the calipers ... the hose is bolted on with a "hollow" bolt.

Did you remember to put on the copper crush washers?

One would fit between the caliper and the hose end ... the other would fit between the hose end and the head of the hollow bolt.

Normally this SHOULD leak if you screwed it up ... but I remember a guy working for me ... forgot the crush washers ... and we had a DEVIL of a time trying to get a pedal.

Oddly, the system would suck air in ... but not leak fluid out.

 

Thanks for all the help. I will try that oddshot. Itll proly be in the morning tho.

Your right also. the flex hose doesnt screw into the caliper it bolts in with what ive heard called a banjo bolt. But yea i put that hose on right and its through the frame and connected to the metal brake line everything there is good.

Ive been pondering and im pretty sure that i just have a massive amount of air in the whole system.
but thanks a whole lot to everyone