Power Brake Booster

[727]

So i'm having an issue with my Power Brake booster. The brakes work fine when vacuum is disconnected. When vacuum is hooked up the pedal goes to the floor on its own. Anybody had an issue like this?

The car is a 1965 Chrysler 300. I know it's not a B body but everything should function the same as other models.

 

[BeeKool]

Booster needs rebuilt or replaced. If originality isn't important just go to parts store and get replacement.
Is the master cylinder leaking at all?
If so.
You can put by an aftermarket booster/MC Assy. for $250
I'm not sure what just a booster would cost probably half

 

[727]

i have the booster disconnected and the brakes work fine.

 

[BeeKool]

My guess would be a diaphragm or some internal component in the booster has gone bad.

 

[727]

I was thinking that something was amiss inside of the booster.

 

[mopar 3 B]

You checked the vacuum valve on the booster for proper operation? When the brake pedal goes to the floor do to brakes lockup?