help with brakes

[4x4mexicano]

The other week I was coming off the highway and I went to slow down from about 70mph and the brake pedal went straight to the floor and the truck would not stop,(not a fun thing to happen)I ended up dropping the truck into 2nd and used the emergency brake to slow down and get her home. I looked in my haynes manual and talked to a couple of friends and they all said its the master cylinder, so i replaced it and still had the same problem. Next we went to the brake booster cause it sounded like it had a vacuum leak after we put the master cylinder in. Now I still have the same problem but now Ill get a pedal once in a blue moon but then I loose it again. I was told rebleed the brakes. I rebled them 3 times and still had the same problem. I talked to another buddy who told me to try gravity bleed them and yet I have the same problem. Does anyone know whats wrong with my brakes by chance or can point me in some kind of direction?

 

[Johnny Reb]

The other week I was coming off the highway and I went to slow down from about 70mph and the brake pedal went straight to the floor and the truck would not stop,(not a fun thing to happen)I ended up dropping the truck into 2nd and used the emergency brake to slow down and get her home. I looked in my haynes manual and talked to a couple of friends and they all said its the master cylinder, so i replaced it and still had the same problem. Next we went to the brake booster cause it sounded like it had a vacuum leak after we put the master cylinder in. Now I still have the same problem but now Ill get a pedal once in a blue moon but then I loose it again. I was told rebleed the brakes. I rebled them 3 times and still had the same problem. I talked to another buddy who told me to try gravity bleed them and yet I have the same problem. Does anyone know whats wrong with my brakes by chance or can point me in some kind of direction?

Check for leaks from end to end. Replace the check valve going into the brake booster,check your vacuum lines for leaks and you might have to re-bleed the brakes more then once. Besure and check you brake lines and wheel cylinders for leaks. Just because you replaced you brake booster with a new one-you can still get BAD-NEW ONES.

 

[4x4mexicano]

I checked for leaks cause that was what I originally thought was wrong with the truck. I am in the process of checking for vacuum leaks but if I do not find any I might just return the booster for another one since it's not that hard to replace, just to see if thats it.

 

[shift1313]

can you pump your brakes and build up pressure? Did you bleed the abs module when bleeding the brakes?

 

[4x4mexicano]

If i pump the brakes it will build up presseure but then Ill loose it again. I bench bled the master cylinder, and the bled the four wheels and something else. I'm not quite sure what it was but it had a bleeder ***** on it so i bled it. It is where the two brake lines go into from the master cylinder.

 

[Johnny Reb]

chevy car that had a junction

If i pump the brakes it will build up presseure but then Ill loose it again. I bench bled the master cylinder, and the bled the four wheels and something else. I'm not quite sure what it was but it had a bleeder ***** on it so i bled it. It is where the two brake lines go into from the master cylinder.

Sometime a leak in the lines are hard to find. You may need to take the take the line support braces off , to get the line away from the frame and then look behind it for leaks. To me it sounds like air is re-entering the brake system. You may also want to have someone listen for a vaccum leak-at the vaccum booster ----when you let off the brake. Does the pedal feel SPOONGY? Does it feel hard or solid? Iwill keep watching this topic and try and help you figure this probllem out. Now you might have a JUNCTION--BOX-------in the line under the cab. If you do. You might try takeing the bleeder bolt out and watch it for fluid to come out. Then put it back in. Then re-bleed your brakes again. Maybe Mike will have an idea. He knows these Fords real good.,but I will keep trying to figure something out.

 

[shift1313]

If i pump the brakes it will build up presseure but then Ill loose it again. I bench bled the master cylinder, and the bled the four wheels and something else. I'm not quite sure what it was but it had a bleeder ***** on it so i bled it. It is where the two brake lines go into from the master cylinder.

The spot your talking about should be the rear abs unit. there is also a proportioning valve around there but i dont recall them having a bleeder on it.

Did you check the check valve that pushes into the booster? if this is junk it needs to be replaced before you go any farther. If its not "checking" then when the engine gets low on vac you have no power brakes.

 

[Johnny Reb]

The spot your talking about should be the rear abs unit. there is also a proportioning valve around there but i dont recall them having a bleeder on it.
Did you check the check valve that pushes into the booster? if this is junk it needs to be replaced before you go any farther. If its not "checking" then when the engine gets low on vac you have no power brakes.

Thanks Shft, what Shift is talking about is -it is a plastic valve that goes into your brake booster--it will have a rubber line that carrys vacuum -from your intake manifold------it will probably cost about $5.00. Thanks for remindeing us Shifty

 

[4x4mexicano]

But would that cause my pedal to go to the floor? Ill take a picture tomorrow of the thing I was talking about before that has a bleeder ***** on it.

 

[BroncoJoe19]

Search through miesk5's site broncolinks.com and maybe here too.

I recall that there is a proportioning valve for the rear ABS and that it allows .... (well I don't really know, so I'll just make stuff up that sounds good to me.... ) when a wheel locks, it will allow extra pressure to bleed off. I am pretty sure that if there is a problem with it, it will allow the pedal to fade, I don;t think it would allow it to fall all the way to the floor.

I recently replaced both of my rear wheel cylinders and did a gravity bleed. The first time in my life that i did a gravity bleed, but I had no one around to help. Personally I am not confident that it fully bleed the lines, and although my brakes seem fine, IMO, they are a little soft. When you did your gravity bleed, did the master cyl ever run dry?

Does your brake pedal still go to the floor?

 

[4x4mexicano]

Sorry it is taking so long for me to get back to you guys. I have been extremely busy with work and school the past couple of weeks that I have no time to look at the truck. Hopefully friday i will have time to work on the truck and get back to you.

 

[Maddog]

Hey,

First, I missed the part about the fluid. May have been in a different thread that I didn't read. Are you loosing fluid? Second, most vacuum issues also cause you ride to run ****** while I don't disagree that it may be vacuum just taking from a different angle. Also, you parking break works normal?

Also, don't take this the wrong way but explain how your bleeding the brakes please.

Thanks

 

[thetacman]

Sorry it is taking so long for me to get back to you guys. I have been extremely busy with work and school the past couple of weeks that I have no time to look at the truck. Hopefully friday i will have time to work on the truck and get back to you.

Hey my bronco the back brakes wont work and its the proportioning valve but at the ford dealership it will cost 500 dollars to replace