Re: Power brake booster engages on its own.

Posted by d c On 2015/3/20 18:24:05

Yup to all howard said. You mentioned replacing the brake lines so you must have been pumping the heck out of the pedal to bleed unless you used a hand vac or pressure bleeder. You did not say if you replaced hard lines fr n rr and the rubber flex hoses. Best way to diag this is on a lift or jackstands with all 4 up. Engine off, spin all 4. If free start engine just for a few seconds or ensure proper ventilation and try to spin all 4. If they all have drag or are locked- pull up on the pedal and have a friend spin en. If all are free problem is in the vac booster. You can use this method to find bad hoses and pulls on apply and drag on a specific wheel after release.