Well my brakes are spongy...so I attempted to bleed my brakes...had no problems with the back but the front continously had air in them. I believe that its my pressure valve..As it looks like it may be leaking..Im not exactly sure. Also my brake fluid appears "rusty" not what comes out of the new bottle. So I planned on replacing the pressure switch, valve, and master cylinder (dont know if really need to), and brake hoses. How do I determine if my m/c is going bad? there is no leaking fluid that I can tell..If I have to replace how do I bench bleed as I have heard people refer to?? Is there any special tools needed for any of this process I plan on doing?? I didnt know if I would need any flare wrenches...

Where is the best place to buy these parts?? Advance, Car Quest, O Reilly's?? Any specail considerations when I purchase them?

 

So you have no air in your back ones but have air in your front ones?

I would think the back ones would have air in them too with the front having air that bad in them.

Keep bleedin the front.

Master cylinders usually leak where they meet the brake booster...I have no other idea how they would mess up beside the rod not pushing in to allow fluid go to your calipers and wheel cylinders.

If your brakes won't pump at all then your brake booster is gone.

 

NEVER use combo wrenches for brake work, you WILL end up rounding something off. Line wrenches are a must.

It takes a while to get all the old brake fluid out, especially for the rears. Are you keeping the pin on the proportioning valve pulled out when you bleed the fronts?

 

Ok so I did a search on the proportioning valves and it looks like they are hard to come by. This is my daily driver so unless I get one at the junk yard I'm out...

I have not purchased any of the parts listed in my previous post.

The back brakes were fine when I bled them. The front ones seems I couldn't get all the air out. The master cylinder does not look like its leaking because there is nothing wet on the front of the brake booster. There is no leaking from the master cylinder onto the lines below. I did have the pin pulled on the valve when pressing the pedal.

I am not really sure that my proportioning valve is bad...I was going to replace it to make sure I got everything that way I wouldnt have to go thru this again. I dont know any other reason why I would develop air in the lines tho. It just started all of a sudden.. Unless my switch that goes into the valve is broken and is letting air in???

Should I go ahead and replace the M/C and the switch?? Since I was bleeding I was going to go ahead and replace the rubber brake lines...

And when I started...It was pumped and pumped..probably 20 times...How many presses would you expect it to take to bleed the front brakes??

Help me narrow this down!

 

Find an obsolete Ford dealership or search at Rockauto.com or partstrain.com

 

Leave anything that looks ok alone. If theres brake fluid coming from the Pressure switch, just replace that. If the rubber lines arent cracked or swollen, leave those too.

 

How much fluid did you push through bleeding the fronts? I pushed over a quart on an F250 before I got the bubbles to stop. It may be worth bleeding some more.

If that doesn't do it, MC is the best guess. They are readily available new and reman.

 

Aftermarket Pro Valve

 

Ok so here is an update. I have put 64 ounces of brake fluid thru the lines and its still spongy as ever. So now I am going to go buy a m/c and see if that does the trick. I also inspected by valve pressure switch and it looks good so I left it alone. I did check at advance auto parts and they did not have one...just for future reference...where do you get them?? are they a dealership part only??? btw are you supposed to be able to pull out the stem of the proportioning valve by hand?? I could manipulate it by hand and use vise grips to clamp it..

Thanks

 

Well after I replaced my m/c...it still didnt make it any better..So I replaced the booster pump and that did the trick...I was actually getting some good pressure until I turned on the truck and the brake pedal went right to floor prior to replacing booster. But it works like a charm now.

 

Yeah, usually when the pedal does that and won't come back up. It's the booster.