brake issues, any ideas? | Ford Explorer Forums - Serious Explorations

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brake issues, any ideas?

reverend_dallas

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Year, Model & Trim Level
92 Explorer XLT 4x4
So.... my brakes don't have consistant pressure. I'll come to a stop, all is well and literally my brakes decompress out from under my foot. A friend ran a diagnostic, and said it was a sensor issue, something relating to the exhaust system. I went and bought the supposedly broken sensor, but when it came time to replace it, I couldn't find it anywhere. Any ideas?
 



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bad master cylinder
 






It could be a bad vacumme hose to the booster or even worse a bad brake line. Check your front brake lines first to see if they are fraid or cracked. If they are REPLACE THEM.

Then I would check the seal behind the master cyclender to booster. The advice of a bad master cyclender without asking more detail is just a JOKE

A bad sensor on these ABS units would not cause the peddel like that. you are loosing pressure somewhere, you need to look and find where it might be due to it might be a bad booster diaphram, bad seal between master and booster, broken line, bad caliper, ect. I have never seen a sensor on the ABS cause this issue.
 






Definitely sounds like a fluid loss issue, which may show up on the ground under the truck.

Rear brake wheel cylinders that are just starting to go bad may exhibit this type of pedal for a short time, then they typically fail and hold no fluid at all (which shows up on the ground).

A really simple test is to park the truck, turn it off, and pump the brakes. If you're losing pressure, get a helper to pump/hold the pedal, and get on the ground and look at all four wheels, brake lines, etc. to see if you see any leaking fluid.

If you're not leaking fluid externally, it may well be a master cylinder issue.

Mike
 






brake fluid and such

I thought at first it was a fluid issue too, but haven't lost a drop. Would a bad brake line cause it to stop inconsistantly like that? Sometimes it stops fine, other times it will start out fine and by slowly lose pressure until I've got the pedal to the floor, with very little braking power. It helps if I pump it, which suggests to me that it is a seal or a vacuum hose.

Thanks, and if you can think of anything else I appreciate it.
 






if any master cylinder goes bad, the pedal will have pressure the slowly work its way to the floor if at a red light.
 






if your not losing fluid then its your master cylinder. if the vacuum booster was leaking vacuum the pedal would be getting harder, not softer.
 






i have had this problem on numerous vehicles.
 






I thought at first it was a fluid issue too, but haven't lost a drop. Would a bad brake line cause it to stop inconsistantly like that? Sometimes it stops fine, other times it will start out fine and by slowly lose pressure until I've got the pedal to the floor, with very little braking power. It helps if I pump it, which suggests to me that it is a seal or a vacuum hose.

Thanks, and if you can think of anything else I appreciate it.

To answer your first question, if it were a fluid line problem, it would show up as an external leak. Once that happens, you basically get no brakes (or just one channel, really weak brakes).

With the symptom of somewhat weak stopping followed by foot-to-floor and very weak stopping, that could be the beginning of a bad wheel cylinder, but they don't usually last long once they start leaking. When the problem is just starting, you don't lose much fluid and may not see it on the ground after driving.

If you do the test I mentioned in my prior post (with the truck off, pump and hold), that will usually speed up the killing process of a slowly dying wheel cylinder. A weak boot will not hold up long to this pump/hold technique. I also found a bad brake line on my (Ford) RV recently with this old trick.

Again, if you do this test thoroughly and don't see fluid coming out, I agree with these other guys, could be the master cylinder.

Good luck, keep us posted.

Mike
 






could be those damn rubber lines too.
 






egr valve?

So, the diagnostic says I have a faulty EGV valve. Is it possible this has anything to do with the brake problem?
 






no
 






just great....

well, apparently that's broken too. At the risk of sounding like a moron, where is the EGV valve? (on 92 Explorer 4x4)

I think I got the brake thing figured out. A seal between the master cylinder body and the brake fluid resevior is faulty. It wasn't leaking fluid, but when I pumped the brakes enough it would hiss at me and brake fluid would bubble out slowly. Thanks the help.
 






looking for recommendations for a reliable master cylinder. while replacing said item is there anything else that shoould be done, besides the fluid?
 






I just bought mine at NAPA.

Take the hoses off the master. take out and put the new Master in. Bleed the Master with the Bleeder that is provided ( make sure the Bleeder hoses are in the fluid in the Master), have someone hold the brake pedal down slightly as you reconnect the Brake lines to the new master. Chances are you wont even have to bleed the whole system if you do it this way.
 






for best results in bleeding a master cyl it should be bench bleed, that is clamping one of the mounting ears in a bench vice, run the bleeder tubes into the resevore and then with a screw driver or socket extention compress the master till all the air is out, by putting the master on the vehicle and bleeding it out you do not get full movment of the master cyl and can trap air bubbles inside. after bench bleeding then put it in the vehicle and bleed it at the connection lines at the master then againg going around the bleeders starting at the right rear, left rear, right front and finishing with the left front.

also before diagnosing it as a bad master, as with sated above check all the lines for an external leak, then pull the drums and check the wheel cyls, the next step if no leaks are visible. line lock the hoses (the rear hose and the two front hoses) then WITH THE VEHICLE IN PARK!! start it up and check to see if the pedal sinks. if it sinks then the diagnosis is the master cyl.
doing it this way can narrow down the problem. I have had bad calipers give the same problem as a bad master cyl.
 






dealing with a soft pedal on 92 xlt, 2wd. but a couple of ?'s 1st. had the brakes done almost 2 yrs ago at a shop that said the abs valve/module was not working. read some threads where this valve can be by-passed. where is it located and what type and size fitting to replace with? is that causing the rears not to bleed? i did bench bleed the new MC before installation and when connecting the lines.
 






catdaddy,

If I were you, I would also check the condition of the rear wheel cylinders. Those rubber boots eventually leak, and they are not replaced as part of a normal brake job. They should have been inspected, but if they were replaced, you would have been charged above and beyond the normal brake job price.

When the boots leak, the brakes won't bleed correctly, and you will lose fluid (slowly at first) which you should be able to see on the inside of the rear tires when it gets bad enough.

As for the ABS, we have front ABS on 94 Explorers, so hopefully someone else can help you.

But, definitely look at your wheel cylinders. If you don't know their age, I would just go ahead and replace them as a preventive measure. For me, this is good peace of mind. I've had them let go while driving, not long after I did a brake job, and it was a VERY eye-opening experience. Ever since, whenever I do a drum brake job, I ALWAYS replace the wheel cylinders.

Mike
 






can't find my paperwork or remember everything but the rears were totally shot and "rebulit", new rotors and pads for the front. will putting the code reader on it tell me anything? no apparent leaks anywhere.
 



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the code reader will only give you ABS information providing the light is on. Like I posted in this thread before you should be able to disable the ABS by unpluging it. the downside is the idiot light on the dash will stay on. if the shop who did the brakes previously said there was a problem with the valve and it is causing a soft pedal, barring any kind of leaks in the system it may just have an air bubble trapped in the valve. one of the nasty things I have with ABS. you can try bleeding the system, but you may have to get it power bleed to get the bubble out, also check the adjustment on the rear shoes as they control your pedal height and firmness.
 






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