Please offer some guidance...93 Blazer...brake pedal slowly goes to the floor when pressed...no fluid leaks and I don't ever have to add fluid...I replaced the master cylinder with a rebuilt unit (bench bled properly)...no help...bled the system at each wheel...no help...I don't know what else to try...it leaks down at the following rate...sitting at a stop sign if I have to wait for 5 cars to go by I have to take my foot off of the pedal and press it again.

 

Sounds like air in the system or possibly a bad 'new' master cylinder... Sometimes they can be a royal pain to bleed.

 

if you drained the lines empty then the ABS thingy could have air in it, and its a real PITA to bleed. I notice there is bleeders on top of this blazer one, the Explorer I had needed to be bled with the ABS tool the dealer has. Maybe try cracking those bleeders on the ABS?

 

My 90 fullsize had the same issue it was the abs system. I just bypassed it. I'm sure you don't want to do that but that's a good place to start

 

I had trouble bleeding all the air out of the lines on my jimmy after opening up the system. It might help to keep bleeding it out. I had fluid with no bubbles coming and didn't have a solid pedal, but just kept bleeding it out and eventually i saw a group of trapped bubbles come out.

Aparently air can also get up into the abs block and can be a problem. If you can't get any more air out of the system it would be worth it to look into that.

 

If it's in the ABS, you need a special tool (actually two of them) to bleed ithe air out. Check around. They're real simple tools and the prices on them range from (I bought mine for about $6.50 each) to like over $30.00 for the exact same tool. The air gets in the high pressure accumulator in the ABS unit and you need the tools to get it out.

 

OK...the plan for now is to swap out the rebuilt master cylinder for another and to bleed the system lots more (also read somewhere that repeated actuation of the anti-lock system while driving may work out any air in the ABS unit?)...just got finished replacing the power steering pressure hose (a pain) and am currently replacing the CPI due to massive leaking...I have had this truck since new and it has been trouble free until now....