1998 Nissan Frontier

Brakes problem
1998 Nissan Frontier 4 cyl Two Wheel Drive Automatic 110, 00 miles

My son has a '98 Nissan Frontier. He described that his brake pedal goes to the floor (some back pressure) but with no braking whatever. No loss of fluid in the reservoir; no sign of a leak. I figured it was a master cylinder, that the fluid was just blowing by the piston but I replaced it with a new mc and the truck is doing exactly the same thing, pedal to the floor, no braking at all, not even sporadic. There are definitely no leaks. I guess it's possible the brand-new mc is defective but that does not seem likely. Anyone have any ideas?
December 7, 2009.

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