I adjusted my timing a bit and took it for a test drive. I'm driving around (slowly fortunately), and slowly but surely my brakes are losing resistance. Finally I pulled over and called a buddy.

Here are the symptoms:

4 drums
Going VERY slow, brakes fully depressed, car WILL stop after a short glide
Fluid good
Vacuum Line good
No Leaks
Pressure builds back when car is off (not completely though), but once car is on again, no pressure.
Wife isn't mad, so she didn't cut the lines

I just changed out my carb and manifold, but I've been driving it for a month now with absolutely no break problems, but is it a factor?

Does anyone have any idea what the heck is going on?

Thanks

BTW...it's a 69 cutlass

 

WOW! That's a mystery for sure! (it's a power brake system I assume?) Are you sure none of your wheel cylinders are leaking? Maybe you just need to bleed your system real good!

 

Can you pump it and get more resistance? If you just push on the pedal does it slowly sink? If yes to either, it's likely a master cylinder.

 

I can only pump to get more resistance when the car is off. When the car is on, there's ZERO resistance

 

Check the booster to carb line again , mine got knocked off one time and I just had enough braking to stop real slow. If there is not fluid all over the floor it must be vacumn problem or lots of air in the system.

 

I'm pretty confident it's not the vacuum line. It's on there pretty good, and all of the other ports have a good vacuum.

There is a build-up of residue at the base of the master cylinder, and the resovoir on that side was 2/3 low, the other side was full.

I'm prepared to change the master cylinder and bleed the brakes, but I just want to make sure that's the right fix.

This morning w/o seeing it, my mechanic said it probably the brake booster.

Now I'm just unsure what to do.

 

I have brakes again...hooray!...it was the master cylinder. It was a pretty easy fix!...thanks again for all the help!

 

CONGRATS!! GLAD to hear it! Great that you're back on the Road again!