Hello,
I found this forum on the web and I am coming here as I have absolutely nowhere else to turn. I have a 1996 Chevy Blazer four-door LS (insurance calls it a "Tahoe"). I really loved it, great snow truck, good for hauling. But lately, it's been having some serious brake issues and I may have to sell or junk it if I can't figure this out, as I have been at this for three weeks now and can't keep a truck with stupid braking problems. Long story short; from driving it alot and salt roads and rust, I had to end up replacing all the brake lines, hydraulic hoses on the front, new calipers, pads, rotors and new wheel cylinders on both rear drums. I can't get the system to bleed no matter what. Try doing each wheel with dad stepping on the pedal, tried gravity bleeding. Nothings working. I have a squishy brake pedal. When I start the truck, it's even worse, the pedal goes all the way to the floor with ease.

The MC has fluid in it. It's not leaking after I ran all new copper lines on it to the back (front already had new steel lines from a few years ago a shop did). We can't get the thing to bleed and I am completely baffled. I feel like I am going in circles trying to find an answer to this problem. I am attaching here a photo of the MC as well as the ABS and the combination valve. I noticed the ABS module has two bleeder valves. Cracking these open never results in any brake fluid. I notice there is also these two valve things on the back of it, they push and pull out.

The proportioning valve, I notice on the front there is no "thing" in the middle, I don't know what it's called. But on the back side of it, there is a tiny gold button/rod that feels like it can be pressed. This is not on the front side of the proportioning valve, I can fit a screwdriver all the way through it. Could this be the problem? Or is it the ABS? I'm SO confused. This truck seems so complicated with this ABS crap and combining drums and disc brakes. I really don't think it's an issue with the MC. This thing was braking fine until the lines were replaced and everything, now all of a sudden it doesn't work anymore. can someone steer me in the right direction? I am coming here as a last resort. If I can't solve this as I said, I'm gonna have to sell or junk this Blazer. This is getting annoying and ridiculous. I never had problems with brakes before like this, I've done brakes many times now on other cars without these issues.

 

#1 if you actually did run copper lines stop trying to bleed the brakes because you have more problems that - Copper line is not strong enough to be used a brake line - steel or stainless steel or nickel alloy only

 

Okay; first of all I finally got the brakes bled. As long as it holds up now... Browsing through these forums, I noticed someone say to turn turn on the ignition but don't start the car when bleeding the brakes. Does something with the ABS module. I only tested it 500 feet up the street and back but it was stopping nice and smooth.

Second, the brake lines; they're actually a copper/nickel composite known as "cupronickel", I'm not sure if I am allowed links here as I am a noobie, but it is called "copper nickel brake line tubing" on Amazon. Summit racing also sells it. 25 feet for $25 bucks. Last year, I put polyarmor steel lines for my fuel lines and they are rusting hideously already. Also, the previous owner before me had a shop put steel polyarmor lines in the back and they rusted away horribly, basically caused me to play whack-a-mole with trying to patch leaks in it till I decided to run all new line to the back. I've researched it thoroughly... not only have I heard nothing but positive things about the stuff (and not one thing about them failing), but they are also starting to legalize it everywhere for brake line use. The nickel in it I suppose makes it a safe material for use on brake line jobs. Obviously I only did a quick test drive with it to know if it holds. But I will say...it's 110% easier to work with than steel lines. Bends and flares way easier. Made some excellent double flares out of it as well. The main reason I got them, they're not suppose to rust away so badly. We'll see how it holds up.

 

Luck with the lines - You would be amazed just how many times I've run across a DIY repair and standard copper lines were used because it bent and flared easy. And after they split wide open it was brought to me to run new steel alloy lines.

 

I checked out the cupronickel brake lines. Everyone selling them claims DOT approval for use as hydraulic brake lines, so if this is true they should be just fine.

 

Copper nickel alloy lines are cream of the crop imo. Almost make running brake lines enjoyable(imagine that!). They fall into place when you bend them, flare very easily, and don't rot out every 10 years like steel.

they are not like copper lines in that they expand when brake pressure is applied. It is 100% safe for road use

I bought a Dakota that needed brake lines to fix and sell, and it came with a roll of the Cooper nickel alloy. I'll never go back to using steel lines again.

here is a chart I found comparing the strengths and limits of the Coppernickel(CN) compared to regular steel brake lines. No major differences.

 

, I noticed someone say to turn turn on the ignition but don't start the car when bleeding the brakes. Does something with the ABS module.

Never knew this, good info. Can you expand on the procedure? Or link to the thread?