2003 Lincoln Town Car Vacuum booster

GUY T CLARK

MEMBER
2003 LINCOLN TOWN CAR
V8
2WD
AUTOMATIC
80,400 MILES

Been to the deliver twice on this problem. Brake work fine when you apply them and no problem with the ABS working. The question is if I apply pressure on the brake pedal it will slowly go the floor when the engine is running. Engine off the pedal is firm after about 1 inch movement.

Dealer replaced the master cylinder and put in new fluid and bleed the system. Pads are good and no leak's showing any place. The pedal still went to the floor with the steady pressure applied. Took car in the second time and they bleed the system again. The save effect was still there.

The ford service mechanic said this is normal for the vacuum booster on the Lincoln. The steadily pressure is bleeding off the vacuum and the pedal will move down. But if you turn the engine off and apply the pressure the pedal will stop going down after about 1 inch and this proves the vacuum booster is O.K.

The brakes work fine at all stop intersections and no problem on stopping fast.

Is this normal for the boosters to allow the pedal to go to the floor?

Thanks

1 Reply

CARADIODOC

MECHANIC
33,738 POSTS

Hi Guy T Clark. Welcome to the forum. Yes, this is characteristic on some cars and leads to a lot of wasted diagnostic time. GM cars are particularly bad for this but some Fords do it too. While the pedal does seem to go down too far, that amount of travel while driving would cause the wheels to lock up. This can be misleading while standing still. As long as the braking power is normal, the system is working as designed.

Caradiodoc