Brake issue (all of the sudden)

[Kowal]

On my 69 Charger. Power Disc Brake car. Had been working fine for several years, no issue.

Went to a cruise today and when I drove home the brake pedal went all the way to the floor, where I was able to get some braking action if I really stepped in to it. If I pumped the brakes, the pedal improved though not quite to normal.

Normally the car is fine with a good, high, pedal. There is a fairly big cam that means if I am not careful with what I am doing I can run in to vacuum issues with the booster with multiple braking actions while idling, but this wasn’t that.

To get home, I anticipated what was happening and pumped the brake to give myself some braking action. There are no leaks.

What do you guys think?

 

[Fran Blacker]

Probably master cylinder if there are no fluid leaks. If if an original master you might want to sleeve it. Run a parts house master until original is done.

 

[PurpleBeeper]

Yep, sure sounds like a master cylinder

 

[Ranger16]

I'll make it unanimous.

 

[mobileparts]

With N O leaks -- all pressure originates from the Master Cylinder....
As you are depressing the brake pedal, brake fluid is rushing past the failed rubber parts inside the master cylinder (the "wrong way") ....
and by pumping it some, you are getting 10 % to 20 & of braking ---- which is better than ---- ZERO --- but, obviously, not enough.
Your master cylinder has indeed failed.... I can service it with a NEW aftermarket Master Cylinder; and I can have an Original MOPAR
Master Cylinder -- STAINLESS STEEL Sleeved......... Yours, Craig... Good that you made it home safe and sound (with higher heartbeat, undoubtedly!!!)

 

[Kowal]

Thanks to all above. I thought the emphasis on "NO" leaks was interesting. Well, went out in the heat wave and figured out what was going on. I checked the Master, and was surprised to see that the front brake reservoir was almost empty (I had no fluid on my painted garage floor, I check all the time...honest!). Anyway, I did have a slight leak that had shown up, the brake line to the front passenger caliper had worked loose and when the brakes were pressed it was leaking, mostly on to the tire which mostly threw the fluid up in to the wheel well. Tightened it up and stopped the leak, will wait for a cooler day to check the front brake bleed. So I guess the bit of stopping power that I did have was my back brakes.

 

[mobileparts]

The point of " N O Leaks" was the important part....
Definitely bleed when you get a chance, because air has been introduced to the system...
That could hopefully be the whole issue -- and you might be ultimately good to go -- and stop.....
Yours, Craig

 

[ckessel]

Check your booster. With the manifold vacuum and master leak, you may have fluid down in the booster where it could start leaking out onto engine bay stuff and peel paint.