Ford Truck Brake Problems

[sublauxation]

Not sure where to put this but I hope somebody can help. I have an 04 Expedition and when I hit the brakes really quick the pedal falls to the floor. It pumps up quickly, then acts normal again.

There is no brake fluid leaking. I bled the brakes and had a hard time getting anything out of the rear driver side caliper. The first couple times I cracked the bleeder nothing came out, and the pedal only went down a little with firm pressure on the pedal. I finally got a little air spurting then got a couple solid streams of brake fluid. The other wheels all bled as normal. I took the truck for a spin and when I hit the pedal it went to the floor again. I tried bleeding again and the same thing happened. I bled about a quart of fluid through the system.

I'm guessing it's either a caliper or the rubber hose to the caliper , but wondering if anybody else has any thoughts. With the wheels on it looks like the pads are wearing evenly in back, but I haven't taken them off to have a closer look. Everything seems normal with regular driving. Thanks for any help

 

[dockwrecker]

Re: Ford Truck Brake Problems

Is this an ABS truck? You should get it checked at the dealer if it is, ABS pumps and valving can be horrifically tricky with special bleeding procedures.

 

[sublauxation]

Re: Ford Truck Brake Problems

Yup, ABS. I've read there can be some tricks but was hoping to get off easy since there is one side that's acting different from the rest. I've also read that bleeding ABS is only a problem if a reservoir has gone dry, though not sure if that's true. On that note I miss my pre-ABS, pre-computer, pre-technology vehicles.

 

[wifisher]

Re: Ford Truck Brake Problems

How did you get air in the brakes to begin with? Was there a component replaced? System opened for some other reason?

You say that the problem is if you hit the pedal quickly. How does it act if you press it normally? Is the pedal low all the time, or is there pressure at the top of the stroke?

 

[sublauxation]

Re: Ford Truck Brake Problems

No idea why/how air got in, nothing has been recently replaced, I've had the truck a couple years now. It acts completely normal unless you literally slam on the brakes quickly. Then it falls flat but with a couple slow pumps it acts normal again. The pedal is at the top with good pressure with any normal driving.

 

[rbh]

Re: Ford Truck Brake Problems

Unless you have a hole in your brake line you master cylinder is KUPUT/TOAST.
Get new master cylinder, bench bleed, RE and RE, Pump the air out of the lines.

 

[sublauxation]

Re: Ford Truck Brake Problems

Would it be a bad seal in the master cylinder that only gives with extreme pressure? I have no other problems with braking and with the truck turned off the pedal doesn't creep to the floor at all. Would the problem with the one caliper be related to the master cylinder or coincidence, or any of the above?

 

[rbh]

Re: Ford Truck Brake Problems

Would it be a bad seal in the master cylinder that only gives with extreme pressure? I have no other problems with braking and with the truck turned off the pedal doesn't creep to the floor at all. Would the problem with the one caliper be related to the master cylinder or coincidence, or any of the above?

YUP, well pretty much.
the plungers o-rings break down and,
(I want to use the word bypass, but thats not right)
Anyways the force you are pressing on the fluid to push it down to the brakes is not making it out of the master cylinder.

 

[wifisher]

Re: Ford Truck Brake Problems

I am thinking more toward ABS pump than master. A master usually will not act the way you have described. You may have more than one problem. You have air in the system, which means there is a leak somewhere. The lack of fluid while bleeding a caliper is a sign of a restriction somewhere in the system. Finding that restriction will probably lead to the problem. If the master was causing the issue, it would cause the same issue on the diagonally opposite wheel.

Follow the line that would not bleed back toward the master, and bleed it at each connection along the way. When you start getting fluid and relieving the system pressure, the restriction is after that point.

 

[sublauxation]

Re: Ford Truck Brake Problems

I do eventually get fluid out from the caliper if that means anything. I would have thought an ABS pump would kick off a code of some sort, I had it checked at a parts store and nothing comes up, ABS light doesn't come on either, for whatever that's worth. Would a master cylinder create a code in the computer?

The more than one problem option sounds right unfortunately. I was going to tear into it over Memorial Day but am a little afraid with no shops open as a backup if I really screw it up.

 

[wifisher]

Re: Ford Truck Brake Problems

You will not get an ABS light from any mechanical problem. The code can only be set by a component that gives feedback, I.E. sensor, actuator, etc. Something electronic. Master cyl will not. The ABS pump might, but not all the time. BTW, if the light is not on, there is no code. No need to check it.

You said you eventually got some fluid from the caliper, but the fluid should squirt immediately upon opening the bleeder, and the pedal should lose all pressure. If the pedal does not go to the floor, there is a restriction. That wheel probably has no brakes at all in normal operation.

Try this next time you drive it: When you reach your destination, hold the brake pedal with moderate pressure for the last half block or so. Get out and immediately check the temp of all four rotors. IR guns work well, otherwise just reach a finger in and be careful not to burn yourself. If the wheel that is not bleeding correctly is not at a similar temp to the others, it has no brakes. (Brakes are nothing more than a heat generator.)

 

[rbh]

Re: Ford Truck Brake Problems

I am thinking the reason it was hard at first to get fluid out of the one slave cylinder is because it was plugged with gunk, your repeated brake applications finally broke through.

(and yes you can have a gunk build up on both sides)

 

[DJ]

Re: Ford Truck Brake Problems

You can't open up, diagnose or bleed an ABS system without an IDS tool.

 

[wifisher]

Re: Ford Truck Brake Problems

You can't open up, diagnose or bleed an ABS system without an IDS tool.

What's a IDS tool?

Been working on cars for a long time and never heard of that.

 

[puddle jumper]

Re: Ford Truck Brake Problems

What's a IDS tool?

Been working on cars for a long time and never heard of that.

You need some one with a ford or newer snap on scanner to activate the abs to bleed the system. my first thought is the master also.

 

[sstaz]

Re: Ford Truck Brake Problems

Never heard of one either and I work on ABS systems all the time. A scanner is needed sometimes but that is rare.
To the OP, if rust is not an issue try cracking the brake line from the hose and see if it bleeds normally there, if it does you have a bad hose.
I have ran into problems with the ABS unit and flushing the system out (if there is gunk in it) usually helps. This is where the scanner can come in handy, or you can bleed it normally then take it out on a dirt road several times and lock the brakes up to activate the ABS system then flush/bleed again.

 

[mrchev]

Re: Ford Truck Brake Problems

it sounds like a two part problem. possible l/r flex line or caliper blockage. if you open bleeder and pedal take a fair bit of pressure more then the others to get fluid to move. is it possible that your are going into premature abs when slamming the brakes on, that will give you the feeling the pedal is going to the floor. the 4x4's are known for cracked relucter rings on the front axles, ,and you won't get a code.try to find abs relay or abs fuse and unplug it. start the truck and the abs light should stay on. Now the abs electrics will not work with the light on, it's like normal brake system.re-road test and see if its still doing it. if it is ok then you are going into premature abs and probably have a cracked ring or possible to much play in wheel bearing.for the left rear wheel try undoing the bolt that holds the line to the caliper when it doesn,t want to bleed. if the pedal drops then you have a bad caliper. if it still don,t then undo the other end of the flex line, if it doe then you have a bad flex line. and you can work on abs without a scan tool depending on the problem.

 

[DJ]

Re: Ford Truck Brake Problems

IDS (Integrated Diagnostic System) is Ford's scan tool. Combined with the VCM (Vehicle Communication Module) the tools can read all codes, re-flash modules and perform pin point diagnostics. It is the standard held held tool for Ford/Lincoln dealers.

 

[sstaz]

Re: Ford Truck Brake Problems

Good idea mrchev, that would eliminate the ABS electronic system. Usually though a bad sensor, bearing or cracked ring would show up at normal braking, usually when you just come up to a stop.

DJ, you got me on that one. Never worked at a dealership before.

 

[puddle jumper]

Re: Ford Truck Brake Problems

Never heard of one either and I work on ABS systems all the time. A scanner is needed sometimes but that is rare.
To the OP, if rust is not an issue try cracking the brake line from the hose and see if it bleeds normally there, if it does you have a bad hose.
I have ran into problems with the ABS unit and flushing the system out (if there is gunk in it) usually helps. This is where the scanner can come in handy, or you can bleed it normally then take it out on a dirt road several times and lock the brakes up to activate the ABS system then flush/bleed again.

You only need it if you replace the (cant remember the Name) ABS valve block.