1989 Chevy C1500 Brake system

[Dusty Moore]

Alright My fellow GMC/Chevy GMT 400 peeps,

 

I got an issue with 1989 Chevy C1500 5.7 350, I have swapped out my rear axle from stock with 14 bolts semi float 9.5 with conversion kit brake, so had to replace few brake lines, but i also replace powered vacuum brake booster, master cylinder, dump/isolation and proportioning valve. So basically my entire braking system have been replace with brand new ones, and im still having issue with having BUBBLES in my brake fluid, so Could anyone tell what else could cause bubbles in the Master cylinder???? spent wayyy too much on the brakes, at the point where im about become Fred Flintstones and using my feet for braking.  

[richard wysong]

Did you bench bleed the master? Could be you have a crack in a flare on the lines or 1 that is not seating correctly or a defective/wrong master cylinder. If I recall there were MANY different masters for the same truck with different bore sizes etc back then but that wouldn't account for air in the system. Where exactly are you seeing bubbles? in the reservoir or the lines when bleeding? It is also around the time they were switching to metric brake lines/ fittings so attention to detail in the parts is critical