What would cause the brake pedal to drop when the engine is started
After replacing the master cylinder on a 66 T Bird the brake pedal now goes to the floor
when the engine is started, this must be an issue with the booster
If you bled it proper,then yes i would agree,booster.
Check all your vacuum lines to the booster. There is probably a "Y" connector and one line may be off or loose.
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