My brother-in-law has a '96 Chevy Suburban with ABS front and rear (3-channel system).

The brake pedal goes way down, done all the brakes, bled till the cows come home, etc. etc.

I checked the Kelsey-Hayes ABS system, no internal leaks I could find. Accumulators are not moving when stepping on the brakes.

The combination valve, they say to push in the stem while bleeding. However, brake fluid comes out when I do this. And, when hitting the brakes, that stem/rod comes out about 1/8-1/4".

Is this normal?

 

Ok Art here is my failed attemot to help you, my fault not yours.

I own a 04 suburban. My brother in law is one of them ASE certified mechanic types has his own shop, got so many certifications on his wall it looks like wall paper etc etc... I asked him about my burbs brakes because they seemed "soft" compared to my Ford. He told me that while the Ford has a high hard brake pedal the chevy's have a much softer braking system and consequently can get a lot more "push" out of the pedal.


I don't know if that helps at all or if your scratching your head thinking "is there something wrong with that guy????" Maybe someone with some actual mechanical skill can help you out....

 

ANYONE have any idea if I'm supposed to get brake fluid from the push-pin on the end of the combo valve?

 

No, you shouldn't. It might be sucking air in there as well.

 

That's what I figured. I kept getting a slight amount of air out of the rear while bleeding no matter how long I went. I bet it was sucking in air right there.

Oh well... I'll report back if that was it.

thanks!
art k.

 

For what its worth, I had a 95 Suburban and took it to the dealer a couple of times for a soft/long push brake pedal they told me that is normal for that vehicle and they all did it.(nothing to do with the valve question)

 

Thanks!

I've heard the same thing, and while I'm all warm and fuzzy inside after my brother-in-law borrowed my 2001 SD (brakes are AWESOME stock), there's still something really wrong with this thing that is MORE than the average "spongy brakes in a Chevy".

It didn't do this until the last few years. The truck was bought new by my BOL's BOL, and he says he never had this problem.

 

we had a 95,99, and now an 03 and they are like that

 

jake, the only problem is that this wasn't this way all along, it's only a new thing in the last few years...

I plan on changing the combo valve... we'll see how it goes from there. It degrades over time, so I'm leaning towards the combo valve sucking in air.

 

That's probably the problem-

 

Replaced the proportioning valve, bled a bit, and it's a much different pedal now.

I get resistance about 1/3rd of the way down, and it retards forward motion

I have to bleed a little more, but it looks like I found the problem.

Note: A GM mechanic living next door to my mother-in-law says it's a pretty common problem.

 

Hey Art.. got a question for you. What is the proportioning valve? Is it the master cylinder or a part of it? Got a link to a picture? I might be needing to do this to a Tahoe soon, well after we get the steering box replaced. It seems to have decided to puke out bits and pieces out to the ps pump. It's just a matter of time till it finally grenades.

 

In the Suburban I'm talking about, it's bolted to the rear side of the ABS valve assembly (modulator).

You know what I'm talking about right? The brake proportioning valve?