Brake Pedal slowly goes to the floor. 1995 RAM 2500 - 5.9L

Brake pedal slowly goes to the floor when constant hard pressure is put on it. I replaced the master cylinder because of this, and with the new unit on it's still doing it. With the pedal on the floor, and the
accelerator pressed the truck does not move. Is this normal or something to get fixed. I'm pulling an 11000# fifth-wheel. Please help!
Marsh
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snipped-for-privacy@gmail.com wrote:

Did you also replace the vacume booster?
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.boB
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wrote:

any fluid leaks in the rear?
I know its an obvious question, but stick with the basics.
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No Leaks, new wheel cylinders and calipers.
I did not replace the vacuum booster.
Chris Thompson wrote:

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If there are no external leaks, the MC is bypassing internally. There seems to be a lot of reports of brand new MC's being bad right out of the box.
A booster won't cause the problem you're having.
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Sounds like a faulty replacement. It can happen

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