Crazy Brakes
 

I have got a ghost in my brake system. Here's what is going on...

My brake reservoir was losing fluid somehow, but there was no fluid tattle tells (like fluid puddles or pulling during hard braking)... I topped it off with dot 3... no more fluid loss (for almost 2 months now)...

Went to check it the other day and the gasket in the top of the reservoir was bloated like it just had christmas dinner... the thing won't go back in.... I dried it off with a paper towel and let it set for a couple of hours ... went back in fine, but looked distorted...

Now... last night, I was coming home and the pedal started acting crazy... it would go to floor like I was crushing grapes for wine- but the truck would stop... then the very next time I'd push the pedal it was like there was a cinder block under it - harder than chineese arithmatic and the truck wasn't getting any brake appliaction... I almost drove through a fence on the way home... used the e-brake to get the rest of the way home and get the truck in the garage... so it's definitely a hydraulic issue.

I have been reading and seeing lot's of info posted... but I'm not sure where to start. I have had the this truck for 3 years now and not done any major brake work... just pads... so I'm thinking about flushing the entire system with fresh dot 3 (it's the recomended fluid... might go to dot 4 but I want to make sure it won't eat the seals first)... then I'm going to rebuild the calipers, replace the flex lines in the front, replace the rear cylinders with the GM 1 ton units, and reset the ABS computer (unplug it for 10 mins) and then adjust the rear brakes and the parking brake and see where that puts me... if I still have issues, what is the next logical place to look??? The master cylinder? The vacuum booster??? The ABS proportioning valve??? What is this lockout valve I keep hearing about and where is it? It sounds like it's internal to the master cylinder???

I can find my way around under the hood, but if anyone has any input it is MOST welcome... Thanks...
Johnny