Rear abs trouble

[maniac_3_2000]

I have a 1991 ford explorer with rear abs. I have been having trouble getting it to bleed because the guy before me left the brake hose off on one of the front wheels, and allowed water to get in the system. I have been able to verify that the abs hydralic unit was rusted shut. Before I replaced it I couldn't get fluid to go past that point. This past weekend I replaced the unit and got fluid to get to the rears, using a vaccum pump, at the lines right before the wheel cylinders. I was not able to pull fluid through the wheel cylinders, so I replaced those. After being able to get fluid through the wheel cylinders using the hand vaccum pump, I still got no brake action (I did also bleed the fronts which I have had no problem bleeding, with the vaccum pump, or with an assistant on the brake pedal. So after all this I tried bleeding the rears with an assistant on the brake pedal, and all I could get to come out each time I opened it, was a few drips. It's alsmost like the master cylinder isn't pushing fluid to the rears.

I have bleed the master cylinder on a bench, and both the front and rear ports pushed fluid through fine and had no trouble bleeding it, so it doesn't make since to me.

One thing I dont know is, I was told when installing the new hydralic unit, to bleed the system before installing the wiring harness to it, or the computer would detect air, or low pressure, and close the valves on me, but I dont know if that's true. I am wondering if I need to install the harness so that maybe it well open it all the way or something so that I can bleed it. I am about to purchase a pressure brake bleeder that installs on the cap of the master cylinder and bleed all 4 wheels that way, That way if I can get good flow in the rear, the only thing it could be is the master cylinder then. But before I spend 50 dollars on this tool, if anyone could give me input I would greatly appreciate it.

 

[FIND]

are your rear wheel cylinders good?

Why did you start a new thread? You realize when you do that, you are going to start getting people repeating things that may have already been said, or there may be someone who may be able to help you but gets confused on the chronology of the events... In this case, it won't make a huge difference, but starting additional threads just clogs the boards. If someone had something to add that was helpful, they would have done it in your other thread.

 

[maniac_3_2000]

The rear wheel cylinders were bad, and have been replaced. I looked at it again today, and tried to bleed it with the engine on for the vacuum to the break booster, it only improved fluid flow out the back a little, but not enough to actually have the rear brakes engage at all.

I am starting to still think either the break booster is bad, cause when I push the break, it feels like when I start to push it, its not even touching the master cylinder, and then I feel it hit something half way, and then start to actually push something. I was on alldatapro, and it showed the break booster does have a thick rubber piece, that if it gets out of alignment, it said it can either fall off and you'll have trouble breaking, or it could cause the pin to get stuck and not be able to break at all. It's either got to be that or the master cylinder, but I would still like people's opinion on this matter before I go spend more money.

The only reason i did that was because everyone got convinced I was talking about an 01 explorer, because that is what was listed next to my name, and I wanted to be clear I was talking about a 91, so I started a new thread, also I tried to clear things up, but i got no response after a day. I normally wouldn't of restarted a thread.

 

[FIND]

Are the rear brake shoes good and the slack adjusters adjusted properly?


Please spell it brake. Break is an entirely different word that means something entirely different.


gee, you waited a whole day for responses......

 

[maniac_3_2000]

Yeah actually when I replaced the wheel cylinders I did the brake shoes and the hardware, and I adjusted the adjuster, the E brake works, but of course no pedal brake.

Yeah and I type and dont spell check. It's a bad habit, and its probably never gonna change.

 

[FIND]

Well, if you were able to bleed all the way through with a vacuum pump and get good flow, AND you are certain you have all good hardware from the master cylinder back, then your master cylinder is probably bad.