Wifes Suburban probs.

DEK196

Member
Posts
13
Reaction
0
We have a 97 3/4 ton with a 454 in it and the brakes are doing some weird stuff, sometimes they go to the floor and feel as if Jello is under foot. At times it feels like I am pushing against a wall, no movement at all. I have replaced the master cylinder, the hydraulic brake booster and bled them with the old pump and hold method. I had a mechanic buddy say that there is a bubble trapped in the ABS valves and only the dealership has the tools to fix it. I took it there and they said that I needed about 2500 bucks worth of brakework! They test drove a 1/4 tank and never found the brakes to be soft or out of adjustment? I am asking you guys because I have seen some serious knowledge about this stuff on the board. Any remarks appreciated greatly and namecalling is a must! Thanks, Donnie
 

tedmales

Well-Known Member
Posts
541
Reaction
10
take it to a shop and have them pressure bleed it. they have a cap that fits on top of the master and its connected to a hose that goes into a tank that has brake fluid on one side of a diaphram and air in the other. you open the valve and it forces brake fluid into the system. this will get all the air out. I always use the old way and pump, pump, pump. if you take vaccum line and put it on the bleeder screw and put it into a cup of fluid you can pump out the air and take back in the fluid. just make sure to keep everything full and it usually gets out the air. If it is not abs then use a oil can squirter and fill it with brake fluid and back bleed by pumping fruid in the wheels and out the master. that works very well, but be sure not to do this to an abs vehicle. good luck
 

tkr

Well-Known Member
Posts
521
Reaction
4
If you suspect there's air in the abs system, a Tech2(GM scan tool) needs to be used to operate the abs pump several times while your depressing the brake pedal. Then a normal bleeding procedure needs to be done. Not many shops other than the dealer will have a Tech2. But in my experience, the symptoms of air in the system don't come and go. When the pedal goes down to the floor, are you sure the ABS isn't engaging? Can you here the pump running when it happens?
Secondly, if this is a hydroboost system...where the power steering pump provides the boost instead of a vacuum booster....I wish you the best of luck. We've had all kinds of strange problems with those things that we've never figured out. A few years back we had a customer who had taken his truck to the dealer with the pedal spongy and going very low. The dealer basically replaced the entire brake system but the problem was still there. He brought the truck to us, and we went through the whole system again, including the hydroboost system, and never did get the pedal back where it should be. Since then I've seen about a dozen other trucks with the same problem. Very strange....
 

DougM

Well-Known Member
Posts
746
Reaction
9
Take the Burb out in a dirt lot and hammer the brakes. This will activate the ABS pump. Take it home and bleed again.
Had the same issue on my Jeep when I let the MC run dry when changing out a brake line. You will definitely notice ABS kick in if your in the dirt.
If all else fails then head to a shop and have them run /bleed it.

good luck
 

CanyonMan

Well-Known Member
Posts
190
Reaction
0
I have a 97 1/2 ton GMC 4x4 with the same damn problem. Sometimes I have a great pedal, other times not at all. Adjusting the brakes works for about a day then it starts all over again. The ABS seems to kick in very aggressively at times and sometimes it doesn't seem to come into play at all. In the dirt, it always comes on. I have actually thought of taking it out of the truck once my extended warranty is up and I've paid some more of it off. There are definitely times when I DON'T want the ABS to work. Mudding and power slides in turns are good examples for me.
 

TDORSloppy

Well-Known Member
Posts
482
Reaction
1
I accidently let my bosses 95 Z71 brake system go dry when bleeding his brakes and it did the same thing. Turns out that when the ABS control goes dry, it needs to goto the dealer for that Tech2 system bleed. We tried everything from scanners to presure bleeding to anything else we could think of (worked a Hyundai dealership). Call up the Chevy dealer and they had it fixed within the day.
 

DEK196

Member
Posts
13
Reaction
0
Thanks for all the input, we are hopefully going to score the parents 2001 Expedition. If we get it, the burban goes to the dealership for a bleedin' and into the trade express she goes. Again thanks for all the input, it's much appreciated. Donnie
 
Top