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Discussion Starter #1
I’m really at a loss here, brake pedal goes to the floor after the car has been started has plenty of pressure when the car is off.

I have replaced the rear hard lines across the axel and put new pads,rotors and calipers on this truck as well as a new master.

Yes everything was bled correctly and bench bled the new master.

No brake lights come on nor an abs light, no leaks either.

This is the second weekend in a row I’ve done this and got nowhere.
 

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‘01 Silverado 2500HD 8.1/Allison 5sp xcab long bed
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3,382 Posts
Howdy and welcome, Jimmy.

Let’s start with some context. Whatcha drivin?
 

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The bottom line is air in the system.

Try a vacuum bleed.
 

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Discussion Starter #5
That’s how I bleed the brakes for this was a vacuum bleed as well as just a standard 2 man bleed.

Same results, once the car is on and running no brake pressure in the pedal at all.
 

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2000 Silverado Z71 4x4 5.3L 460k+ miles w/ GM rebuilt motor and trans
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879 Posts
Did you put the cap back on the master cylinder reservoir?

It matters...as I found out 2 weeks ago.
 

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Discussion Starter #8
I fixed the problem, there was a massive amount of air in the system and then found out some new brake lines I replaced weren’t tight enough, I tried to match the amount of threads from the old fittings but I guess they were tightened enough to when I bled the brakes it was sucking in some air.
 
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