With engine running pedal slowly goes to the floor

2004 NISSAN TRUCK
200,000 MILES • 3.0L • 4 CYL • 2WD • MANUAL
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CHERRY PICKER
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Nissan Cabstar 2004 hard brake pedal when engine stopped. When engine running pedal goes to the floor slowly. changed master cylinder and servo. still no change.
Mar 31, 2019 at 7:00 AM
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SCGRANTURISMO
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Hello,

This sounds to me like you have a brake fluid leaks somewhere. When you have a leak in you vehicle's sealed brake system, it will not be able to build pressure and the brake pedal will slowly fade to the floor. Brake fluid acts like hydraulic fluid by building pressure and squeezing calipers together with brake pads on them. The brake pads apply friction on a rotor which is attached to the wheel stopping your vehicle.
I have included a link for you to go to down below:

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

Please go through this guide and get back to us with what you find out.

Thanks,
Alex
2CarPros
Mar 31, 2019 at 10:22 AM
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CHERRY PICKER
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After clamping off nsf brake pipes the pedal works great. no leaks, pistons working.
Apr 2, 2019 at 7:40 AM
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STRAILER
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NSF pipes? are those the flex lines or?
Apr 4, 2019 at 11:55 AM
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CHERRY PICKER
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Hi, yes they are flexible pipes.
Apr 5, 2019 at 9:11 AM
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STRAILER
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It sounds like you have air at one of the wheels. can I ask if the truck has ABS brakes? Also try to block off either the front or back to see if we can isolate which end of the truck is causing issues. Let me know what happens.
Apr 8, 2019 at 10:21 AM
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CHERRY PICKER
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Hi Ken, when engine is not running brake are hard when running slowly goes to the floor clamp off nsf FLEXI pipes when running brake good.
Apr 8, 2019 at 12:36 PM
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CHERRY PICKER
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Ken it’s not ABS.
Apr 8, 2019 at 12:38 PM
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SCGRANTURISMO
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Hello again,

Where do the NSF pipes run to?

Thanks,
Alex
2CarPros
Apr 8, 2019 at 3:11 PM