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Posted: 10/4/2011 3:54:51 PM EDT
[Last Edit: 10/4/2011 3:57:17 PM EDT by FAIL-SAFE]
This is a bit of a continuation thread from my previous thread about my cousins truck.

Its a 2003 F-150 Supercrew, 4.6 V8, with cruise control, and disk brakes on the front and rear. This is also the truck that still has a rough idle.


Anyway, teh brakes, he dont have zem. There is virtually no resistance on the pedal. On level ground, with the brake pedal to the fire wall, the truck will barely stop, in fact you have to start slowing down well before getting to a light, and you have to hope. You have to hold the pedal there or the truck will begin to roll forward. If on an incline or decline, forget it. They will slow him, but they wont stop him.

We suspected the brake master cylinder was out, because some power steering fluid accidently got poured in the BMC reservoir. He's pretty sure he got it all out. We removed the BMC, and the seals are still in very nice shape. It was very difficult to push the seal in.

We noticed that in my garage, we can smell burned gas under the cab of the truck. I am starting to believe he has a exhaust leak, and that he is not getting enough oomph to the brake booster, which in turn is not giving him enough power to operate the BMC.

Another friend mentioned a vacuum leak, and that is valid. However in our limited ability we havent detected a vacuum leak. Is there a solid way besides spraying B-12 and listening?

Yet another friend mentioned the EGR valve could be f'ed up. The kid at Auto Zone mentioned this in passing, but his shit head manager overruled him.




HALP! He wants to sell this truck, get as much as he can, so he can buy something more suitable.
Link Posted: 10/4/2011 3:59:47 PM EDT
[Last Edit: 10/4/2011 4:07:58 PM EDT by TuskenRaider]
Nothing you listed is causing your problem. Let me confer with a friend and I will get back to you.


Do you have any ABS codes?

Can you get a hard pedal with the engine off?
Link Posted: 10/4/2011 4:22:10 PM EDT
Bleeding all the air out of a brake system can be challenging. Did you bleed the brakes? Did you do it right?

If you have a rough idle, it could be a lot of things, but in my long experience, Ford has shitty ignition systems.
Link Posted: 10/4/2011 4:29:48 PM EDT
If the brakes go to the floor, a vacuum leak is the least of your friends problems especially if he rear end someone. Even a bad lawyer will win that lawsuit due to driving a vehicle with a defective brake system.

Link Posted: 10/4/2011 4:33:24 PM EDT
Okay here is what i got.

You need to make sure the brakes are bled of air.

Check for any DTC's in the ABS

Do an ABS stop somewhere safe. How you do this is get to about 30 mph and slam on the brakes you should feel the ABS activate the break pedal and make a grown noise.

Do this in a safe place with lots of room and best on dirt or gravel road.

If nothing works then do this.

Cap the outlets of the ABS pump so you only have the Master cylinder and the ABS see if you can get a good pedal if not then you have an ABS bypassing internally .



This is all based on the fact that you said the master cylinder is good. I am assuming that you are not losing brake fluid anywhere. Fluid can leak into the vacuum reservoir and not be seen for a long time.


Last thing Check all of the rubber lines for swelling make sure they are not soft.



Link Posted: 10/4/2011 4:42:26 PM EDT
[Last Edit: 10/4/2011 4:43:39 PM EDT by Seabee_Mech]
A failed booster or vacuum leak won't leave you without brakes, the master cylinder will still work without the booster, the pedal will be stiff feeling without the assist of the booster but you'll still have brakes.

You can't look at the cup seals in the master cylinder and tell if they are bad (outside of some really screwed up seals). There are return springs inside the master cylinder so you'll always feel resistance on the piston whether the cup seals are good or bad.
Link Posted: 10/4/2011 6:52:17 PM EDT
Chances are that if power steering fluid was put in the brake system all the rubber parts in the system are trashed.

Try flushing the system until you get clean brake fluid from all four bleeders. If that doesn't help, then you are going to have a very expensive repair.

Rough idle could be any of a million things, but would not contribute to a loss of braking.
Link Posted: 10/4/2011 7:49:07 PM EDT
The rubber seals in the BMC partially absorbed whatever type of brake fluid they were filled with from the factory & therefore, that's the only fluid that should go in there. There could have possibly been a reaction with the PS fluid, potentially destroying the seals.

If the truck has ABS, the "home garage" bleed method isn't going to remove all the old fluid. In the case of brakes, a qualified shop can bleed them fully with a pump system. Same holds true for trans fluid, BTW. I change my own F/R brake pads, but I have the fluid done at a shop to ensure the entire system gets fully recharged. This one of those things that is better to shell out for unless you happen have the specialized, expensive equipement yourself, which most of us don't.
Link Posted: 10/4/2011 8:02:50 PM EDT
He doesnt drive this truck, except when we are working on it, and only then on private and way backroads.He has a company truck, so thats not an issue.

On some backroads we have gotten the truck up to 45 MPH, and when we hit the brakes, it takes a very long time to stop, but it does eventually stop. If he stomps the brakes really hard, and I mean really hard, the truck will come to a stop quicker, and then they will lock up. He has to turn the truck off and back on to get them to "unlock".

When we flushed out the brake resevoirs, right after the incidental addition of power steering fluid, we refilled the resevoir with DOT 3 brake fluid. It has not leaked any at all.



There are no ABS indicator lights, just the Service Engine Soon light.

The truck has rough idle, but when it is at say 1,000 RPM it smoothes out just fine.
Link Posted: 10/4/2011 8:06:40 PM EDT
[Last Edit: 10/4/2011 8:13:09 PM EDT by FAIL-SAFE]
What does "DTC" mean? Someone here mentioned it.

TuskenRaider, if you live around D/FW, you are free to have a look see
Link Posted: 10/4/2011 8:13:53 PM EDT
As already stated, the booster is not the problem. In a car with working power brakes you can pull the booster line completely off. The pedal doesn't get easier to push in –– it gets more difficult. It will feel exactly the way it does when you press the brakes with the motor off.

If the pedal is going to the floor, and you're not out of brake fluid after every drive, there's air in the lines. Use a good pressure bleeder or vacuum bleeder, and don't sweat the ABS; if you're terribly concerned, after you get the brakes working again with clean fluid, go give the ABS a good workout on a gravel road, then flush and bleed again.

Link Posted: 10/4/2011 8:58:54 PM EDT
[Last Edit: 10/4/2011 9:04:00 PM EDT by JC_Conn]
Since I just went through something similar with my 2002 F150 Supercrew...

For the rough idle:

1. Replace PCV (about $10 from Auto Zone). Be sure to take the old one with you because Auto Zone has some weird PCV listed in their computer for 4.6L Triton V8s of that era that doesn't fit. Compare the old one to the ones on the wall to find the right one (gray plastic, blue trim, slight half Acme thread on the base.
2. Check rubber elbow that connects the PCV hose to the intake, between the rear of the intake and the firewall. Trace from PCV on passenger side valve cover toward the firewall. There's a lot of heat concentrated in this area over/behind the intake and firewall and the rubber elbow is prone to melting. Look at it from both sides and give it a tug. If it looks distorted and not a smooth curve, it's melted and letting extra air in. Normally, though, if the ECU has compensated the fuel-air mix to make up for a significant leak, you'll get a Bank 1/2 Lean DTCs. Find a piece of molded rubber hose, something that fits tight enough and use hose clamps if necessary to mate to existing PCV hose from valve cover.
3. (Longshot) Clogged or restricted Fuel filter –– $15, plus the tool to release the fittings. Be sure to depressurize the fuel system with the inertia switch on the passenger side kick panel.

If you're not getting any DTC (as in Check Engine Light is on), it's hard to say specifically it's vacuum related but the two above are pretty cheap to start out with.

Normally, I would say:

1. Spark plugs and COPs on offending cylinders (if DTC present indicating misfires in particular cylinders)––I prefer a mechanic for this.
2. MAF sensor ($150 - $25 core charge)––You can do this yourself after giving the current one a good cleaning with electronics cleaner.
3. IAC sensor or DPFE (EGR) sensor thingy––You can do this yourself too if all else fails.

EDIT: Just saw the bit about the SEL light being active –– you need to get the boys at Auto Zone to read the codes that it's throwing –– that'll most likely indicate where to go with your rough idle issue. Bank 1/2 lean is P0171 and P0174 respectively. Issues with misfires in a cylinder are P0300-P0308, where P0301-P0308 indicates the individual cylinder (01 through 08). Have the codes read and post up what you find, that'll help out with the diagnostic process.


Link Posted: 10/5/2011 8:21:48 PM EDT
Link Posted: 10/5/2011 8:35:22 PM EDT
Have you checked the manifold vacuum with a guage?

The rough idle gives me pause as to the lack of brakes.

When I was a pup I had a car with way too big a cam in it. This car had power brakes. Lack of adequate vacuum can cause your issue.

When coming to a stop, I had to put it in neutral and give it a little gas to get it to stop. Some of the other racers here have probably encountered the same thing.

If you didn't, the pedal would go straight to the floor with no resistance whatsoever.

OP, try doing this and see if it makes any difference in your problem.

It's simple and won't cost you a dime.
Link Posted: 11/1/2011 6:54:25 PM EDT
I'm Fail-Safe's cousin, and I thought I'd chime in

We spent a little time working on this bitch the other day. I loosened the bleed valve on the brake line, and drained a bit. The fluid has a green tint to it. Anyways, we noticed that everytime one of us pushes the brake pedal, bubbles appear in the brake fluid reservoir.


We are going to flush the brakes out completely. Open all the bleeder valves and go through several bottles of brake fluid unti. Then we will probably change that master cylinder when we can find one (rock auto screwed up, apw doesnt know when theyll get more in).
Link Posted: 11/2/2011 6:42:46 AM EDT
dfw is big. if you are near allen, let me know. might be able to give you a hand or lend some tools.

if you can hit the firewall with the pedal, either the master is gone, or you have air in the lines.

since you see bubles, that is probably a good indication of air. not familar enough with ford's abs system. some have a built in resovior that has to be bled too to get all the air out of the system.
also you may have to bench bleed the master cylinder.

get new brake line ends with some hose to curve it around back into the master to pump the air out that way. probably your issue if you let the master go dry.
Link Posted: 11/2/2011 1:25:15 PM EDT
[Last Edit: 11/2/2011 1:26:00 PM EDT by FAIL-SAFE]
Well he never let the BMC go dry. He was topping it off when the two fluid got mixed up. I live in Dallas, he lives in Wylie, right between Lake Lavon and Lake Ray Wylie Hubbard.
Link Posted: 12/28/2011 3:49:53 PM EDT
Thought I would let you folks know that we got it fixed.

It was the PCV valve hose. Where its at on this particular truck is in the back of the engine, towards the firewall. Couldnt see it, it was a bitch to remove the old and replace. That said, it cost a total of $7 to fix.

Brakes are good too. All calipers function fine. We flushed the lines out several times until we got clean and clear brake fluid. The brakes immediately came back. Because we bought a BMC, and because it was past its return date we replaced it anyways. Bled them properly.

We are happy.



Now I need to solve the annoying ticking noise we hear when the trucks is driving past a wall. I was told it was a stuck lifter and to add some transmission fluid to the crankcase on the next oil change.
Link Posted: 12/28/2011 3:53:04 PM EDT
Originally Posted By FAIL-SAFE:
Thought I would let you folks know that we got it fixed.

It was the PCV valve hose. Where its at on this particular truck is in the back of the engine, towards the firewall. Couldnt see it, it was a bitch to remove the old and replace. That said, it cost a total of $7 to fix.

Brakes are good too. All calipers function fine. We flushed the lines out several times until we got clean and clear brake fluid. The brakes immediately came back. Because we bought a BMC, and because it was past its return date we replaced it anyways. Bled them properly.

We are happy.



Now I need to solve the annoying ticking noise we hear when the trucks is driving past a wall. I was told it was a stuck lifter and to add some transmission fluid to the crankcase on the next oil change.


The ticking could be a leak at the exhaust manifold.
Link Posted: 1/5/2012 3:26:27 PM EDT
I guess so. The only thing that is really disturbing is you really on hear it when you drive past a wall.
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