Sinking brake pedal

WILLIAM MORRIS2

MEMBER
2002 DODGE DURANGO
4.7L
V8
4WD
AUTOMATIC
200 MILES

Sinking brake pedal I replaced master cylinder and bled all brakes. I have vacuum on the check valve to the intake of I pull the valve out of the booster the pedal does not sink but as soon as I put the valve with vacuum back into the booster the pedal will sink. I pumped the brakes to empty vac and held my foot in the pedal and started car it does not indicate bad booster. Help I am stumped. Please.

Friday, December 30th, 2016 AT 11:19 AM

2 Replies

CARADIODOC

MECHANIC
34,330 POSTS

Forget the power booster. That has absolutely nothing to do with how far the brake pedal moves; only how easily it moves.

Do you have anti-lock brakes? If you do, there is a chance air got into the chambers in the hydraulic controller. You will need a scanner to command those valves to open so the air can be bled out.

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Friday, December 30th, 2016 AT 2:30 PM

KEN L

MASTER CERTIFIED MECHANIC
54,137 POSTS

Hey,

Also check the caliper slides becasue if they are sticking it will cause the caliper to back up slightly giving you a low pedal.

Here is a guide on how to service the slides.

https://www.2carpros.com/articles/how-to-replace-front-brake-pads-and-rotors-fwd

Please let us know happens so it will help others.

Best, Ken

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Saturday, December 31st, 2016 AT 2:31 PM