Brake question

I have a brake question. I have a 1996 chevy Silverado. I have had it for about 4-5 years. I bought it from my dad. It has 315,000 miles on
it. It has always had a soft spongy pedal. Brakes seem to work, but like I said the pedal sinks when holding it.
This weekend was a nightmare. I replaced one side of my back drum brakes. I will have to finish the other side this weekend as I ran out of time. I noticed when I was trying to force on the pads in the back, I developed some liquid at the master cylinder boot.
This weekend is a long one so I plan on doing this right. Replacing the other set of rear pads. I guess I need to replace that wheel cylinder now too. (Will I hurt anything by driving the truck this week with one set of new pads on one set of old pads?) For the record, the pads had a lot of life left on them but there were some superficial cracks so I attempted to replace them.
Also, for the last year my antilock brake light has been on.
Anyway, Part of me is afraid to replace the master cylinder and re bleed everything. I have heard of people doing this and somehow getting air on the anti lock module? Have you heard of this?
I appreciate any help and advice! I just want to get this done and be finished with it. This summer by the way I had to replace my vacuum booster. It went out. I have no fluid leakage that I can see by the way.
I appreciate any help!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
stryped wrote:

Take the truck to a competent mechanic before you kill yourself - or worse yet some innocent bystander that didn't realize you don't have any brakes . Unless you know what you're doing it's very easy to screw this up . And brakes just ain't the place to screw up .
--
Snag
Besides , if you take it to a mechanic,
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Wanna bet?
Karl
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

You've got air, at least, in the works, maybe a bad master cylinder and I hope you've got the manual. You NEED the manual and maybe some special tools like a vacuum bleeder to get the air out of the anti- lock system. My b-in-l has a Silverado, a bigger piece of crap I never hope to see as far as braking systems are concerned. The days of shade-tree brake mechanicing without docs are long gone with the advent of ABS. The b-in-l tried 4-5 times to get things back to the way they were after replacing pads and shoes, he finally ended up hauling it in to the dealer. The rear wheels on his had both pads AND shoes, so had discs and drums both. Guess GM was too dumb to figure out how to do parking brakes with discs. Major pain in the ass setting the shoe clearance.
If you replaced the vacuum booster, that usually sits right behind the master cylinder which has to be removed for access. Probably that's where you got the air in. Some can be bench bled with fittings and hoses added, some need vacuum. The manual has the procedures. Just pumping fluid through a cracked fitting doesn't do it anymore.
Stan
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
stryped wrote:

Do you mean it leaked because you pushed fluid back into the MC and it overfilled it, spilling out the top? Or is it leaking out the rear bore of the cylinder, where it bolts up the vacuum booster? If the latter, you will need to replace the master cylinder.

MC will come with directs for bench bleeding. Also should have some plastic fittings and hoses to do it with. If not, buy them separately.
I'd also suggest you buy a hand vacuum pump/brake bleeder. If you have to bleed the whole system, you can do it correctly by pulling new fluid through the system and bringing air bubbles out with it. Do RR, LR, RF, LF in that order. Don't skimp on brake fluid, and don't let the MC run dry. A helper pouring fresh fluid and keeping the MC topped up while you work the vacuum pump is a big help.
It's not rocket science, but it takes care and the proper tools to do it correctly and safely.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
As the pads wear, the calipers close. Which moves fluid down the line, to the calipers. So, you see the fluid is low, and pour more in. When you compress the caliper, you push fluid back towards the master cylinder. And of course some leaks otu the main seal. This is normal.
The rest of it, I'm less sure.
--
Christopher A. Young
Learn more about Jesus
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On May 24, 6:07pm, "Stormin Mormon"

If you do not know the BASICS then don't mess with it! Drums have SHOES! Disc brakes have PADS! DRUMS DO NOT HAVE PADS!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

^^^^^^
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.