hey, new here, just thought i'd see what you guys thought of this problem. I'm not too familiar with these trucks, but I've been working on my buddies 1999 e350 ford van.

the other day we were going out kayaking, and the brakes locked up, we were able to drive it home, but it was obvious the brakes were holding the truck back. decided to check it out today, found one front and one rear caliper were sticking, the dual piston calipers only had one working, which I believed to be causing the pads to get pressed together crooked, and caused them to "lock up" or get stuck.

anyways, got the new calipers on and no more sticking, so I bled the brakes started in the front and went all the way to the back, did every caliper. brakes feel firm with the vehicle off, but instantly when the van is started, the pedal goes to the floor. it still stops okay, but the pedal feel is not nearly where it should be.

I got all of the air out of the system, but the abs light is on, and has been for a while. I'm wondering if there is something else that needs to be bled in the abs? someone was telling me about bleeding the abs motor?

Any help on this would be great, thanks guys.

 

Simple:

You have a bad master cylinder. Replace it.

While you are at it: Replace the cruise control deactivation switch if it has one (extra $15, but a royal pain to do if you have to do it again), and check the fluid level sensor carefully, and if needs be replace it.


When you were doing the calipers, did you do all 4? Should have brand new calipers and pads on all 4 wheels. Rotors on all 4 should have been machined or replaced.

Did you check the brake lines?


Then, check the connection at the pumpkin top for the ABS sensor, and the Front wheel ABS sensor, replace as needed.

 

You still have air in the system. Bleed the brakes again in the proper sequence. Right rear, left rear, right front, left front.

 

on a budget as of now, we're college students, the pads have plenty of life left in them so we did not replace them. we only replaced 2 calipers, the other 2 are working as they should.

I will try bleeding them again, as we did not do it in that sequence. The master cylinder looks fine, I don't see any leaks, and its not rusted or worn. I have heard though, that it can develop leaks at the seams in the back and you will not be able to tell if thats the problem or not.

to me it would make sense that when we get vacuum (start the engine) the master cylinder starts leaking causing the brakes to feel soft. I'm hoping thats not it though

thanks for the suggestions, any more??

 

Master cylinder failures do not necessarily leak any oil or show any external evidence of failure.


If one of the cylinders is worn (typically the front one), it leaks fluid to the 2nd cylinder (rear) and there will be no perceptible fluid leak.

When the rear cylinder fails, it will be a catastrophic total loss of braking.


I hate to say this - but IMHO, you are endangering your and others' lives with that vehicle in that condition.

I don't care if you have no money, or what you do for a living.

Seems there is plenty of money for Kayaking, traveling, and bling bling.


You owe it to other drivers and persons to have the vehicle properly checked by a licensed mechanic and have it brought up to the minimum safety standard in your state.


If you did get into a crash with your vehicle in this condition... there is a high probability that your liability insurance can be voided, or you are stuck with such a high damage bill that you will never work / drive again for the rest of your life.

 

"When the rear cylinder fails, it will be a catastrophic total loss of braking" Not true. There is a safety valve in the prop block that prevents this. When it detects a leak it will shut off the system that failed, fronts or rears. How can you say with any degree of certainty his master cylinder is bad without ever even checking it out ? I only replace parts that are bad. It's bad business to sell a customer calipers, rotors, etc. that he or she doesn't need. Fear mongering & blindly throwing someone elses money at this problem is no way to fix this problem.

If you can't get anymore air out of them, I would look into the proportioning valve's safety switch.

 

No competent mechanic would permit only one side of a caliper to be repaired / replaced without doing the other one --- at the minimum, a complete rebuild / retest.

There is no evidence that the OP even did what would be minimally required in a lawful brake pad replacement job:

Namely, checking rotor thickness, and if safe, resurfacing it before placing new pads / calipers in.


When only one side of each axle is "repaired" in this manner, there is a risk that the other side (of unknown condition) will fail shortly thereafter.


What is at risk is the other side will shortly thereafter, either fail or jam --- resulting in uneven braking that can cause the vehicle to veer to one side.

For exactly the same reasons, tires are matched on the same axle, and no competent mechanic will tell you "one side of the brake good" and just replace the worn pads on the other side, or allow you to mix and match different types / construction of tires on the same axle.


As for this:


The proportioning valve is not intended to deal with front brake failure.

It only "proportions" the rear, not the front brake action.

It is not known if this vehicle is ABS equipped, and if so, whether the proportioning function has been replaced with the ABS programming.


StopTech : Balanced Brake Upgrades


If it is in fact the front brake portion of the master cylinder that have failed (piston seal failure is most common), then the leaked fluid is ending up in the reservoir, perhaps with some going into the rear master cylinder if the seal there has failed too.

Without a disassembly and bench testing, there is no telling.

However, if the brake warning light is "on", most likely, it is the sensor detecting either a low brake fluid condition, or the pressure differential between the front and rear brake systems as being excessive.


Are you trying to tell the OP that it is lawful and safe to continue to operate a vehicle with the brake warning light on?

Sure, try a bleed... but if that doesn't instantly fix it, it is time to see a qualified mechanic.

OP do not appear to be a licensed mechanic in any jurisdiction.

 

jeepmike,

I would try bleeding the brakes in the correct order as in post #3. You might also have the bleed the ABS valve. Does the van have rear ABS or four wheel ABS? If it just has rear ABS then you have to bleed the RABS valve (follow the lines back, you'll see it) after you bleed the rear brakes.

I second the motion to replace calipers on all both sides if you replace one. If you don't do this you will end up with a pull to one side or the other 99% of the time because you have a shiny new caliper on one side that moves as it should and one on the other side that probably doesn't.

gearloose,

You didn't notice that he bled the brakes in the wrong order? And then you tell him without any doubt that he has a bad master cylinder?

I doubt you are a licensed mechanic either. You sound like a know-it-all that doesn't know what he's talking about.

 

Duplicate post

 

The larger problem is mismatched calipers, new pads on one side and not the other, and probably rotors not turned.


I would redo the job first doing a through brake job, that would mean redoing the bleeding anyways.




It appears that you didn't notice this:



If the light have been on for "a while", it predates the brake replacement, so improper bleeding cannot be the the only cause.



Let's get a code reader and see what the ABS module is telling us!


Yes, I do have a problem with people who have money going Kayaking but can't or do not wish to spend $50 to have a professional look at their brakes.

I have been doing brakes for decades --- and I have my own work checked by currently certified colleagues just to be sure.

 

None of which will cause a soft pedal.

I disagree. If the brakes worked fine (with or without the light on) prior to replacing the calipers and bleeding, then the light cannot be a cause of the soft pedal.

Agreed, but again - it's very unlikely to be a cause of the soft pedal.

I agree with this as well. In fact, brake inspections are free in many shops.

So you are not a certified mechanic either? Just checking.

I'm not either, FWIW - and many shops employ mechanics that aren't certified. I have also met ASE certified mechanics that may or may not be able to change their own oil, so certification doesn't mean that much to me.

 

looks like I have to pick and choose the info you guys are giving me, thanks andym for the help, I was talking to a friend of mine and he suggested bleeding the abs valve also. I will try that next.

Andym, you know exactly where Im coming from, and we are planning on taking the van to a shop to have the abs code read and see whats up with that, and to look over what we've done.

I don't believe the abs light is causing the soft pedal. I believe i have blead the brakes improperly, just inexperience working on abs equipped vehicles, the van is not being driven until we are confident it works correctly.

btw, kayaking is free, we have thousands of acres of national parks within 10 minutes of campus and our kayaks have been paid off for years, so you can drop that argument. btw, we have no problem spending the money if need be. Im just Saying... I'd like to save as much as I can for my friend. and if 2 calipers are still in good working order then I see no need to replace them.

also we have not replaced any of the pads, they were all relatively new so we reused them, and the rotors were in good condition.

as of now, I think we just need to re bleed them correctly and see where that takes us.

after that we will have the abs problem looked at by a qualified mechanic.

thanks everyone who helped, I'll get some work done later this week and report back when I have the time.

 

I am certificated, but not as a mechanic.

No mechanic's certification I know of exist for what I am certificated for, which is FMEA.



Now back to this errant brake:




This is the definitive clue that it is likely more than just air / water in the brake system.

It is normal for the pedal to go down a bit (with the application of vacuum boost).


I was waiting for you to miss this symptom ---- and you did.


The key:

If a master cylinder is bad, generally there is no brake warning light that shows --- because the leaking cylinder leaks internally, back to the reservoir.


The definitive proof that the master cylinder is bad is if you can release the brake and then "pump" it and the pedal goes back up.


The final check is that no amount of bleeding helps and the reservoir remains full, and there is no apparent fluid loss --- topping up of the system do not help.


It is possible for a reservoir to be depleted and air pumped into the brakes, so this testing is only valid if the reservoir is full the entire time and there are no other leaks in the system.



For you not to have spotted this is all the evidence I need that you have serious shortcomings in your ability to understand simple hydraulics.

Not to mention the failure to note the ABS light issue.


Whats more, for a person who have 14,345 post and a compelling psychological need to prove to everyone you appear to know your stuff, you demonstrate an attitude that is self evident in this comment:



That is, clearly, you describing yourself.

 

I'm not going to get into a pissing match with you, so instead I'm just going to point out where you're wrong so that the OP will be able to fix his problem despite the bad information you've posted here.

Completely wrong. A brake system with air in it will behave exactly like that. There is no reason to suspect a bad master cylinder yet.

Also wrong. When a master cylinder is bad and you pump the pedal up, it will slowly creep to the floor. That is the sign of a bad master cylinder. I think just about everyone who knows anything about brakes knows this.

We'll let the OP come back and tell us what the resolution is. I am willing to bet that once the brakes are bled in the correct order, including the ABS valve, that the brakes will work fine again and he will not have to replace the master cylinder.

 

I hope you are not driving the van to the garage where a licensed mechanic will look at it.


Also note you only intend to have them look at the ABS light issue.

A complete inspection of the entire brake system is in order to make sure you did not do something wrong or overlooked something.


There is no way you can have 2 calipers on one side go that bad and not have the other side in substantially the same condition or nearly as bad.

Without a tear down, there is no way a visual inspection will tell you what the pistons and bores look like.


Finally, there is the master cylinder.

On a vehicle that old, with miles unknown, it is more likely than not to have the original master cylinder in it.


Get the whole system looked at by a licensed professional.


This is not shade tree mechanic work.


You may end up spending $3 million to save your "friend" $10.