brakes on chevy silverado

working on a 79 chevy silverado c-20 big block brake pedal goes to floor can pump and will get brakes then after a couple of times pedal goes to floor checked master cylinder full, also check hoses and around disc and rears couldn't find any leaks didn't want to pull hub/drum until sure any suggestions

sounds like a master cylinder problem to me? those are fairly easy to replace. Make sure to bleed the new master cylinder prior to hooking up the hard line. Easy to do in a vise. If you find thats your problem. Most "re-built" master cylinders come with two plugs and two short clear hoses for this purpose.

While you are at it (if you haven't allready done this) I would recommend replacing the rubber front brake lines. There were several years including the 79 that the inside liner tends to deteriorate and colapse. When you hit the brake, fluid will get thru but it won't allow all the pressure to release causing the front calipers to constanly have a little pressure on the pads.

This won't cause the problem you are describing, it's almost certainly the master cylinder, but since you will have to bleed the system anyway, It would be a good time.

James

I purchased a master cylinder and put it in, bled the brakes and wallai we have brakes, thxs!