Brake Problem

[1-Dragon]

Hello i'm kind of new to the forums
I'm dutch but live in the usa since 2001 (mind spell errors)
Been reading these forums for several months fixing other problems on my ex,but this is my first post

Using the search function and reading all relevant posts for 2 days in a row now, i can't find any posts with a solution to my problem
So i decided to ask this question:

Since i bought my '93 XLT 4x4 3 years ago i been having break problems

The break pedal is hard before i start the engine
I start the engine and the pedal goes almost to the floor and turns soft (more push and it hits the carpet)
I also have to push pretty hard to get good stopping power
I replaced about all breakparts in the rear except the drums (cylinders,shoes,springs etc)
I replaced the front rotors and brake pads
I bled the front and rear brakes several times, no air comes out
The 4 wheel abs is disabled by pulling the fuses
When i push the brake pedal its hard like concrete and doesn't fade,I keep holding it down and start the engine , poof the pedal falls almost to the floor the second the engine is running and is so soft that i can push it all the way to the floor like i'm stepping on a balloon

Like i said it has been doing this since i bought the car 3 years ago and its our only vehicle, which we use a lot since my wife delivers news papers 7 days a week

All in all for 3 years now i'm afraid every time someone brakes suddenly in front of me that i can't stop in time and several times i had to turn onto a sidewalk or shoulder to avoid a accident and just not hitting the car in front of me

Because i'm on dissabillity we have always been poor and it took me some time to get all those parts replaced when we had some money left to fix the car

Does anyone have any ideas ??


thanks

 

[DeRocha]

It sounds like you could still have air on your brake lines. Try bleeding your brakes again (Plan on running a minimum of a quart of fluid through the system).

Break Bleeding...
Put a clear flexible hose over the bleeder valve.

1) Max out the brake fluid in the reservoir.
2) Open the bleeder and have an assistant slowly press the brake peddle..
3) Close the bleeder before the peddle has bottomed out. (which will prevent air from getting drawn back in).
Repeat the above until no air bubbles are seen and you have extracted 8 oz of fluid per each wheel cylinder.
Note: you need to keep an eye on the brake fluid reservoir to ensure it doesn't run low.. If it drops too low it will introduce air into the master cylinder which will be very difficult to remove.

 

[1-Dragon]

First of all thanks for the response

I have done the bleeding exactly like u discribed several times
pumped about a total of 2 quarts through the system



Can U tell me how it would explane the brakes to be hard and the pedal being high up ,without the engine running
They feel ok untill i start the engine
Then the pedal suddenly drops to 3 inch or so from the floor and i can can push it all the way to the floor applying some more force (air bubble only when the engine is running ? )

Could the deactivated abs system still act up or anything else that is only active when the engine is running ?

My dad thought me how to bleed , he has been a car mechanic for 32 years and used to work for my uncle who has a garage

I have been a car electrician for 4 years but never had to work on a explorer since SUVs and trucks (or any other american fuel sucking car) barely exist in Holland with a gas price of about 6.5 dollars per gallon they are to expensive to drive unless converted to LPG

I have been working on the Ex since i bought it and gained a lot of experience but have problems with the brake system and drive train since

 

[DeRocha]

Easy... when the engine is off the power booster is not working... The power booster's job is to make pressing the brake easier... Therefore when you start the engine the power booster supplies power to the brakes and makes pressing the peddle easier... Did the master cylinder ever run dry? Getting air out of the ABS system and MC (master cylinder) can be a pita... The ABS HCU (Hydraulic control unit) will trap air and a special tool is used to cycle it's solenoids (basically electronic valves) to mimic ABS braking which will allow the air to be forced out..

BASIC TEST
1. With the engine off depress and release the brake pedal several times to eliminate vacuum from the power section.
2. Depress the pedal and hold down with light pressure, 15 to 25 pounds.
3. Start engine.
4. If the power unit is operating the pedal will drop slightly. Less pressure will be needed to hold the pedal down.

Check out these other brake related threads:
Glacier's Brake diary
ABS
Brake problems

 

[sprint29]

A quick note about bleeding proceedure. One thing that DeRocha listed in the proceedure is really important.
When bleeding depress the pedal GENTLY and SLOWLY. What you want to do is move a lot of fluid with the air in it. I see that your dad had been a mechanic for a long time, mine too. An idea a lot of older mechanics used was to push the pedal really hard to bleed. That can actually trap air in the bends of lines ect. It can make bleeding a nightmare. Also it can trip equalizer switches and such.

 

[jimbo74]

what about a bad master cylinder?

 

[1-Dragon]

First of all i'm very happy with all the responces

@DeRocha: Like i stated I don't know what the hystory of the car is before i bought it and it has been doing this from the start so don't know about trapped air in abs or ms
I disabled the 4w ABS since it was interfearing with my braking (rattle in the brake pedal and ABS light coming on) and we didn't have money to let it get fixed
I know the brakes on my EX suck because my wife has a dodge daytona (not drivable anymore) and whenever i drove her car after driving the ex i pushed the pedal so hard with normal braking that the wheels blocked and i got slammed into the seatbelts ,i was used to need that much force with normal braking in the ex
In her car i only had to tip the pedal to get the car braking , in the ex i have to push it hard and far down for the brakes to start slowing the car down and i can't feel how hard i brake since its all spouncy
Well I have to replace the front brake hoses because the outside wall is broken on both so i have to bleed the brakes again


@sprint29: Your right i always hit the pedal fast and hard while bleeding , even my wifes dad said so lol
In the old days ABS didn't exist same with power boosters most cars where i come from don't have power steering or abs anyway and i have always been driving old cars from 1980 - 1982 anyway lol


would be nice if i could just bypass the abs , but guess that needs more then just a few hoses with 4w abs (and money i don't have)

UPDATE:

just found out the abs has 2 in and 3 out lines and a bleeder tool costs like 38.95 on ebay http://cgi.ebay.com/ebaymotors/THEX...ryZ43989QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Sadly i don't have that kind of money laying around and am not even sure thats the problem
But since nothing changed after bleeding several times i start thinking that way

 

[1-Dragon]

I'm thinking about getting a reservoir cap and put a nipple on it to connect to my compressor today so i can power bleed the brakes
the family is going egg hunting so i'll be on my own
Does anyone have a idea how much pressure i have to put on there ??
I read somewhere 45 psi but that sounds strange to me considering the reservoir is only hanging on by 2 O-rings hehe
Any input is welcome

 

[1-Dragon]

don't know if anyone still reads my posts , but i did total bleeding earlyer
There was abunch of debris coming out of the lines and the brake flued comes out clear now
The pressure bleeding worked great at 2psi and i got rid of all the crap in the lines
Sadly with no effect to the original problem , pedal still falls to the floor and feels spoungy

Been looking into MC repair kits since a new MC seems to be far over my budget
They seem to come with 2 borings for my car and i have no clue which one i need
Also i can't take it apart before i have the right parts because i only own one drivable car

Any suggestions ?

Thanks

 

[ma96782]

I would be looking at fixing the vac. booster or the master cyl.......both are costly but, brakes are a SAFETY issue.........for you (your family) as well as others on the road.

I'm NO LAWYER but, IF you drive a vehicle on the road with a KNOWN BRAKE PROBLEM.......you open yourself up to LIABILITY........both CIVIL and CRIMINAL (in most, if not all states).

Aloha, Mark

PS....I did a rebuild on a master cyl once. To be done correctly, you should hone the cyl and measure it for roundness and wear. There are O rings (sometimes cups) to deal with and the possibility of pitts on the piston or bore.

All said an done........I'd rather buy a re-built one.

Don't forget to bench bleed it before installation.

 

[1-Dragon]

U have a point there , i would just have replaced everything in the repair kit
But wouldn't have thought about checking for roundness or honing it lol
Might buy a rebuild one , maybe , a new one is just to crazy $140 we don't have that kind of money laying around
The booster i don't know , it seems to work good , without its impossible to break at all

I bought the xplorer because here in Nebraska u need a 4x4 to be able to deliver newspapers in the winter
Specially in areas where snowplows only hit the streets in the afternoon or some areas not even next day
Had some fun in the morning with the snow flying over the hood
4x4 is a must in those cases