No brake pedal when engine runs

Tiny
68GTCS
  • MEMBER
  • 1968 FORD MUSTANG
  • V8
  • 2WD
  • AUTOMATIC
  • 900,000 MILES
Power front disc rear drum. I get super soft pedal to the floor, when not running, start the car and the pedal goes straight to the floor. I recently replaced everything because it did this before the final put together after paint and body. Help
Friday, May 12th, 2017 AT 4:10 PM

7 Replies

Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
This is about all I have to offer, other than a defective master cylinder

Going give you a link/ there is a link inside of it (lemme know if you do not understand the 'on vehicle' bench bleeding-That's in the link inside of this one)

https://www.2carpros.com/questions/1998-ford-f-150-cant-get-brakes-bleed

Return here with good news!

The Medic
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Friday, May 12th, 2017 AT 7:46 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,490 POSTS
Hello,

Check the bleed and adjustment of the shoes at the rear. Also if the master and booster have been off or replaced check the adjustment of the push rod into the master cylinder.

Here is a guide that might help you.

https://www.2carpros.com/articles/how-to-bleed-or-flush-a-car-brake-system

Please let us know what happens.

Cheers, Ken

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Saturday, May 13th, 2017 AT 6:54 PM
Tiny
68GTCS
  • MEMBER
  • 3 POSTS
Thank you gentlemen for great advice, the only thing I have not checked it the power booster
rod adjustment.

Also my problem gets extreme no brakes when I start the car and the vacuum line is hooked to booster. Rod? Booster? Mc?
This actually happened before I replaced everything but rear wheel cylinders
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Monday, May 15th, 2017 AT 8:24 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,490 POSTS
The wheel cylinder could be causing all of your problems becasue they can let air into the system. I would start by replacing them.

Please let us know what happens.

Cheers, Ken
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Tuesday, May 16th, 2017 AT 11:57 AM
Tiny
68GTCS
  • MEMBER
  • 3 POSTS
Hello ken, I did replace the wheel cylinders now, one did look bad, got excited because I hoped that was it, I put new shoes etc as well, but. Still soft pedal and when car is started the pedal Gascony nothing at all. Goes straight to the floor, there was a parking brake link rod missing on one side.
Anyway am I back to Mc? And maybe rod adjustment?
Thank you
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Wednesday, May 31st, 2017 AT 5:50 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,490 POSTS
Hello,

Please remove the master cylinder to check the push rod. It sounds like you are not getting all of the air from the system.

Follow this guide and try it again.

https://www.2carpros.com/articles/how-to-bleed-or-flush-a-car-brake-system

Please let us know what happens.

Cheers, Ken

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Wednesday, May 31st, 2017 AT 1:25 PM
Tiny
68GTCS
  • MEMBER
  • 3 POSTS
What measurement, or adjust rod out or in? Thanks
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Wednesday, May 31st, 2017 AT 3:26 PM

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