Brake Problems!! Please HELP!!!

1991 Chevy S-10 Blazer 4.3L 4x4

For a while, The brake pedal has been going almost to the floor. It is firm close to the floor, then drops to the floor. The rear brake line was leaking, so I just replaced it and the master cylinder. The master was bench bled, and I bled the lines in the proper order. I started at the Electro-Hydraulic Control Unit (EHCU). When I opened the bleeders, NOTHING came out.... no air.... no fluid. :uhoh: I don't get any more air out of the wheel cylinders or calipers, but the pedal is about 1" to 1 1/2" off the floor. :mad: I think there is air in the EHCU but it won't bleed. I am wondering if debris from the old master got into the EHCU. The ABS light stays on all the time. Is the EHCU junk or is there something else wrong? I need HELP!!! :banghead: Thanks in advance!

1991 Chevy S-10 Blazer 4.3L 4x4

For a while, The brake pedal has been going almost to the floor. It is firm close to the floor, then drops to the floor. The rear brake line was leaking, so I just replaced it and the master cylinder. The master was bench bled, and I bled the lines in the proper order. I started at the Electro-Hydraulic Control Unit (EHCU). When I opened the bleeders, NOTHING came out.... no air.... no fluid. :uhoh: I don't get any more air out of the wheel cylinders or calipers, but the pedal is about 1" to 1 1/2" off the floor. :mad: I think there is air in the EHCU but it won't bleed. I am wondering if debris from the old master got into the EHCU. The ABS light stays on all the time. Is the EHCU junk or is there something else wrong? I need HELP!!! :banghead: Thanks in advance!

are you having someone help you bleed the system? if not follow these directions. engine off, open the first bleeder and have someone push the pedal to the floor and hold it. close the bleeder and repeat this process until there is no more air coming out. on the same bleeder, have the person pump up the pedal with smooth depressions of the pedal ( as opposed to someone just jabbing it to the floor which tends to break up airbubbles ). have them pump it up like that 5 times and then on the 5th pump have them hold it. open the bleeder. when you do that 3 times and no more air comes out move on to the next bleeder. dont let the fluid get too low in the master cylinder.

are you having someone help you bleed the system? if not follow these directions. engine off, open the first bleeder and have someone push the pedal to the floor and hold it. close the bleeder and repeat this process until there is no more air coming out. on the same bleeder, have the person pump up the pedal with smooth depressions of the pedal ( as opposed to someone just jabbing it to the floor which tends to break up airbubbles ). have them pump it up like that 5 times and then on the 5th pump have them hold it. open the bleeder. when you do that 3 times and no more air comes out move on to the next bleeder. dont let the fluid get too low in the master cylinder.

That is exactly how it was done. Just straight fluid out of all four bleeders.

Then try adjusting the back brakes. Yhat might be your problem.

The self adjusters don't always work properly.

Thanks. The rear brakes are kind of worn. I will replace them and adjust them tomorrow after the snow stops.

I've done that job at lease a 1/2 dozen times in snow storms, so you can do it... (I really did when I was young and stupid. It always somehow went good too)

That is good thinking on your part to replace the shoes before they need it. It should stop good then

The drums are worn too. Almost out of spec. They are cheap, so I will get those with the shoes. Hopefully that will help the pedal not have 75% travel! Pretty bad when the fronts are doing what braking there is.

when you put the rear brakes on check your wheel cylinders. before you take the old shoes off push the shoes in on both sides and see if teh wheel cylinder moves freely inward both ways. make sure they arent leaking. gently pull the boot to one side or the other and see if fluid comes out. sometimes there is a bit of water in there which is no big deal, but if there is more than a couple drops of brake fluid in there you might consider replacing those too before they start a bigger problem.

At the beginning of fall this year, I noticed that the right rear wheel cylinder was leaking. I replaced both while I was at it to be safe. Thanks for the advice!

Your a smart man dhodson2004!

I don't think that any one welcomed you to AF

Well here's to you :cheers:

Thank you OverBoardProject! I will let you know if your advice helps my problem. Either way, I appreciate the advice. I took two years of Automotive Training two years ago in high school. This is my first time working on my mom's ABS system with an EHCU. I heard stories about the unit going bad, causing similar problems. After doing the repairs that I have already done on it, I was out of options. I want to explore other options due to the price of a new unit (starting at $520.00! Only paid $850.00 for the Blazer!). I will do the rear shoes and drums. I am also going to vacuum bleed the system to try and get any stubborn air out. Once again, I appreciate your advice and everybody's who have replied to my thread. :)

didnt read all the posts so sorry if this has been asked, but is the peddel stuck down by the floor??

He says 75% travel, so no

Good thinking though DM

prop/metering valves might be shot/... depending on which you coulndt get air./fluid out of

My truck has all of the problems you are talking about. I am stuck with no vehicle right now. I put my Mustang in storage and bought this truck for $400 and its brakes took a dump when driving a few weeks ago. The rear passenger brake cylinder was bad so i replaced both of them in back. I also replaced all the pads and put new springs in. I bled everything. The brakes went to the floor and at the last second, they locked up the rear brakes. The truck barely stopped. I re-adjusted the rear brakes and that isn't the problem. I replaced the master cylinder after benchbleeding it and it still doesnt work. There is a sound coming from the master cylinder and brake booster area that sounds like air blowing when I hit the brake pedal. This is my first Chevy and it is really re-enforcing my already low thoughts on their vehicles. Just wondering if you figured yours out yet.

Where do you live NastE50?

There is a small chance that someone from the board can help you.

To me it sounds like you must have some air somewhere that just isn't coming out.

I had replaced the shoes & springs. I adjusted them and tried the brakes to find that there was some improvement, but still excess travel. :uhoh: I borrowed my brother's vacuum bleeder that I DID NOT know he had. I spent 2 days just bleeding the system. (I figured enough is enough!) I was extremely suprised how much air was stubborn and just wouldn't come out by regular bleeding. You may have air trapped like I did. Thanks to all! :smile:

I'm in the northwest suburbs of Chicago. I drove my truck after continous bleeding. It is better, but it it is still soggy and it still goes to the floor. It feels like there is air in the lines but you wouldn't think that would be it due to all the bleeding we did. I'll discuss this vacuum bleeding with my best friend when he gets back from vacation in a couple days. He might be able to help me with it. Thanks again for your responses.