breaks again !!!!!!!!!

[Jeff Dodson]

Well I replaced the master cylinder AGAIN and still the same thing. When I bleed them and the engine is not running, they stay hard like they are suppose to. When I start it up, thats when they sing to the floor.could this be a symtom of a bad booster. I tried to look at the RABS valve and its behind the gas tank. How am I suppose to get to that to by-pass it.

 

[94johnh]

The RABS valve is on the frame below the drivers door ;3 bolts 2 lines.
I got a rebuilt from napa for like $140 or so. they show 2 parts over or under 8500 gvw.


john

 

[icanfixall]

Your problem is the rear brakes need adjusting. The auto adjusters really don't work. To verify this set the emergancy brake. Does it engage more than half way down to the floor? Now with the "E" brake applied step on the brake peddle with the motor running so you have some vacuum. Is the peddle higher? If so just manually adjust the rear brakes equally on each side and go for a test drive. Its a cheap fix.

 

[Jeff Dodson]

Your problem is the rear brakes need adjusting. The auto adjusters really don't work. To verify this set the emergancy brake. Does it engage more than half way down to the floor? Now with the "E" brake applied step on the brake peddle with the motor running so you have some vacuum. Is the peddle higher? If so just manually adjust the rear brakes equally on each side and go for a test drive. Its a cheap fix.

I just had the rear brakes adjusted

 

[metrojd]

Brakes

What year truck are you working on?
If you can pump up the brakes when the truck is running and the pedal fades I would say it is air.
Most of the Rabs I have seen are on the driverside rail under the drivers feet. Easy to access with a bleader on it.
Did you bench blead the Master Cyl.?
Air is a *****. I have had the same problem and you just got to blead the heck out of the system.
Are you bleading from the bleaders?
I know sometimes you cant get the bleaders open or they are broken off and people try to blead the lines. the problem with that is the fitting is lower than the bleader and there is a air pocket trapped above it.
I would suggest bench bleading the Master.
Than start from the farthest away and blead a dozen times make sure you dont run the fluid out, But one line probly takes more than one resavore full to comlpete the blead.
Dont lose hope, I know it Sucks, But you will get it.
Good Luck
John

 

[Jeff Dodson]

Well, new RABS valve, although the brakes work ALOT BETTER. I can actually feel the rear brakes working now, the pedal still bleeds down. Alot slower but still bleeds down. Any Other suggestions. I am thinking about returning the master cylinder to AUTOZONE and get one from NAPA or someplace that may have quality parts

 

[Mont91]

The parking brake is a good indication if the rear brakes were adjusted properly.
It's a '93 right? These have a selfadjusting parking brake pedal, however if the rears are not adjusted tight enough it won't hold.
Does your parking brake hold the pickup on a real steep hill nose down?
Do what icanfixall suggested. If the pedal does not sink and is higher with the parking brake on then the rear brakes are not adjusted "RIGHT"!!!!!!

 

[TLBREWER]

Jeff

If you are sitting at a stop and apply pretty good brake pressure, the pedal will eventually go down. As long as it doesn't go right down and the brakes don't hold. It sounds like you fixed that problem.

I agree with the others on rear brake adjustment. Unless you did it yourself or were present when it was done, I would not necessarily trust that it was done correctly. Very simple and easy to do incorrectly. I know I have to do both my '91's periodically and it is surprising how much difference it makes in pedal feel. I didn't believe it at first.

As far as the MC is concerned, I use Napa parts a lot. However, it is getting to the point that even some of those parts are not any better than the other suppliers. That being said, If I'm not buying the part from Ford or a custom/specialized supplier, Napa is where I spend my money (way too much of it ).

Tom

 

[Jeff Dodson]

Well I will check the rear adjustment again. I did push the E-Brake and it went probably 1/2 to 3/4 of the way down. As far as a STEEP HILL, this is South East Texas, there aint no hills in SoutEast Texas. But the pedal did not feel any different with the E-Brake on. I guess I will just keep trying. Thanx for yall's in-put

 

[Mont91]

Sounds like things are taken care of. Parking brake sounds good and rear adjustment sounds like its right. I always adjust the rears on my '91 until they rub and readjust when I feel a drop in the pedal.
Most if not all brake systems will bleed down if heavy constant pressure is applied to the brake pedal. Some more then others.
Are you having to pump th ebrakes at a stop light to keep the vehicle from moving?
I know about them hills, or lack of. I lived around Fort Worth for a number of years and they are kind of short of them there to.

 

[Jeff Dodson]

Well i bled the brakes again and I think its good now. As someone said, all brakes will bleed down if constant hard pressure put on them, thats the
ANTI-LOCK right. Well when I drove it seemed great. If I just pushed normal, it stopped great and didnt seem to fade, only if I tried and pushed ******* them. Anyway Thanx for all yalls INPUT, I have never had a problem on brakes as I did this truck and I consider myself pretty efficient when doing brake jobs. THANX AGAIN