Hi I'm new to the site and have an 04 screw that the brakes go all the way to the floor. I pumped them and if you hold them it will gradually release to the floor. I've tried bleeding them with no improvements and no air being released. Any help?

 

Whare are you bleeding them? There are bleeder valves at every corner, and then on some vehicles (actually not sure about F150s) but their is a 5th bleeder poing in between the master cylinder and where the break lines break out to the corners, sorry if I'm no help at all, do you have a manual?

 

It needs a master cylinder. Probably has an internal leak.

I would start by replacing it.

 

But what do you do after that?

 

I would bleed the master cylinder, and make sure its full on fluid, then take the truck on a test drive after pumping up the brakes.

I would gravity bleed the master, then get a friend to push the pedal half way down while I open one at a time. Then close them and tell him to let it up. After a few goes on each line I would have him go to the floor with the brake pedal (slowly as to not shoot out brake fluid on the motor) after a few goes of this I would top it off, spray off the mess with water and drive it.

 

I have been bleeding them at all 4 corners..... I replaced the master cylinder about a month ago because it was going to the floor... it was good till about a week ago when the brakes started dragging up front. Then I replaced the brake hoses from the calipers to the frame. Now I am back to loosing pressure but can find no leaks. I have another master cylinder coming in on Friday to try that... just figured I would see if anyone had any other ideas.

 

Im still saying its an internal leak in the master cylinder. You did bleed the master cylinder when you installed it correct? I dont mean the brake calipers either but the master itself?

 

Yep... hopefully i just got a bad master and the new one will work better.

 

I agree with IRONS1N that it sounds like an internal leak.
BUT - have you checked the entire length of all the brake lines to look for any slow leaks? It doesn't take very many drips for the brake pedal to fall away. And if its over a frame rail or something it might not drip right to the floor.

A few other suggestions - go buy a new container of brake fluid. The one you are using might be contaminated (with particles or some sort of fluid that you can't see). The contamination might be trashing the seals which would explain why the new MC you installed behaved the same way after a couple weeks.

Also - if it were me, I would not bleed the master cylinder first. Hook it up and bleed it on the vehicle. That way you know when the burst of air gets through to the wheel that you have bled the entire system with new fluid. If there is contamination in the system, and you don't bleed everything, the contamination could work its way back to the master cylinder due to the way the master cylinder replenishes and compensates (basically every time you release the brake pedal it pulls fluid from the reservoir and then over the next several seconds it pushes it back into the reservoir). This could be why the last new master cylinder worked fine for a few weeks and then failed.

This will require more fluid (do NOT recycle the fluid back into the master cylinder) but in the long run will be cheaper and easier than replacing the master cylinder every month when the contamination works its way back into the MC.

good luck!

 

Did you bench bleed the master or bleed it with it installed. If so i doubt you got all the air out. You need to BENCH BLEED the master cylinder to get all the air out. I recommend properly bleeding the new master. Like mkosu04 said completely flush the system in case there is any contamination in there. It will take longer but you'll have all clean fluid in the system and it will function better.

Do you have ABS?

 

Just don't get it on the paint...

 

yes, it has abs i believe.... didn't know that was an option anymore. I will bench bleed the new one tomorrow extra good and flush the rest of the system.... hopefully thats all it needs.

 

Put the new master in today with fresh fluid.... everything seems good so far. thanks for the help.