GEEEEZ!!!   How frustrating that must be.  What's the tubing out of the top of the cap doin for ya?  Extra insurance you're drawing some air?  Did ya check the brake vacuum ?  Minimum engine vacumm (according to the FSM) is 17 in Hg or 57.6 kPa at normal operating temperature.  Engine vacuum up to standard?

That's funny, I already replaced the tubing with a plug. I just didn't have one at the time of the picture. It was replaced before we finished messing with it. Don'y need the engine running to get no pressure.

Yeah, that's right, vacuum assist won't help if there's no pedal pressure to start with....  what's the chances that the proportioning valve is/was defective right from the manufacturer (new)?  How do you test the valve to insure it's working... short of installing it?  What happens if it doesn't work correctly?   What other part of the hydraulic brake system would cause this particular problem that you are experiencinig, given you have NO fluid leaks in your system and no air in your lines???   There has to be a smokin gun here.  The smoke is just damned hard to see.

My bet is still master cylinder.

That seems to be both Dave and Forrest's opinion as well. I just don't believe that I could have so many bad master cylinders. And I have replaced many over the years, so I know how to bench bleed them. Plus, there were two other ASE Mechanics that installed new ones for me. Dave is ordering one out of his pocket. If it fixes the problem, I'll pay for it. I'll let you know Thursday when we get it. Now back to wet sanding the boat!

I had some starting trouble with a car years ago.  After pulling the battery (checked okay), I pulled the starter and it checked out okay.  So.....alternator.  Pulled it and had it checked -- "okay".  So.....replaced the starter anyway.  STILL didn't fix my problem.  Back to the drawing board.  Even dug out the alternator again (lots of work) and had it checked -- still "okay".  Lots and lots and lots of head scratching and cussing later..... it turn out the new (remanufactured I think) starter was bad.
 
It sucks when you think you've ruled something out as a problem, when in actuality....not.
 
Your problem has all the earmarks of this.

Well, I didn't have to pay for another master cylinder! He was able to return it, so he's not out anything either. Now he want's to order another $400 LSPV's. I'll post when that happens. This is my boat towing vehicle, it's really starting to piss me off!

It's going in to a different dealership today. We'll see how much this is gonna cost me now. At this point, I don't care, I just need it so I can tow my boat to the lake!

Well, they put another new master cylinder on it, that wasn't it. So they put a new LSPV on, that wasn't it either. So they said I must have a restriction in the lines and replaced them all, still no brakes. This is another $800 into this thing now and I'm no closer to a solution. I think it might go up for sale.

The dealership says they want to put a power booster on next. As their mechanic said," it's the next part to throw at it." When I asked him what the booster has to do with the brakes when the motor is not running, he said again, it's just the next part to throw at it. That answer is not good enough for me. So, if anybody could give me a reason that the booster could have an affect, let me know. I'm done putting money into this just to throw money at it.

Note: With one line plugged, the brakes work just fine, so I have doubts that the booster will fix anything.

"Note: With one line plugged, the brakes work just fine.... "

That's the part that just doesn't make sense.  Three lines is fine but four lines they go soft again.

what does that "blocked off" line go to?

and what did you do just before the problems?

just to work backwards "every action causes a reaction" type thing.......


i want you to fix it just so i know whats wrong, its bugging me now LOL

-Lance

It doesn't matter which line is plugged, so I can't seem to trace it to one area. I didn't do anything to cause this, the brakes just went soft on my way to work. I never took a vehicle to a dealer to get fixed. I finally admitted defeat on this and took it in only to spend way too much to get nowhere. I'll never again pay for somebody to work on my cars! If I can't do it, it'll go to the junk yard!!!!

the last time i had that issue, was when i did a Toyota v6 caliper upgrade on my sas sidekick, basically once i put the larger calipers on it, my master cyl was not large enough to flow enough fluid to the larger pistons inside the calipers.

is it possible that your master did go bad, but the first replacement master was the wrong size (say from a 2.0 4 cyl) and when it was replaced the second time, it was replaced with the same wrong part because they just matched it up to what was on there?

on another note, has anyone looked at the linkage under the dash to make sure nothing has bent or come undone?  i have seen (only once) the bracket that holds the brake pedal assembly, the weld broke, and when the pedal was pressed it would go down and put a bit of pressure on the master, and then just bend out out of the way, to make it seem like the pedal was being pressed to the floor.

The linlage must be good because I have great pedal with 1 line blocked off. You might just have something with the wrong master cylinder though. I was told they were the same part # at both dealers though. I'll be looking into that right away.