You have a leak in the caliper piston most likely due to rust which causes brake fluid to leak past the rubber seal. To fix, you have to either rebuild the caliper yourself or buy a rebuilt caliper from the parts store. If you buy a rebuilt caliper, it will come loaded or unloaded. Loaded = comes with brake pads. Unloaded = caliper by itself (no pads).
vacuum leak
If a coolant leak were caused by brake work, I'd never have that person work on my brakes - ever. Just the brakes, I would think it highly unlikely that it would result in a coolant leak. If they were replacing the master cylinder, then I could see a possibility of someone inadvertently causing a coolant leak, but that would still even be a stretch.
you might have a vacuum leak in your intake manifold
I have to believe that it would be a bad wheel cylinder that controls the back brakes.
vacaum leak or bad throttle position sensor. gm Jim
Possibly a broken motor mount. If it runs good otherwise one cause can be a vacuum leak. The check engine light should be on if it is a vacuum leak.
Because air is in constant supply - thus, a leak in the system won't necessarily render the brakes inoperable, whereas, with hydraulic brakes, the fluid would leak out until it had emptied.
Well, they wouldn't be air brakes then, would they? The reasons for air is that it's in steady supply, and a leak in the system doesn't cause you to use your supply.
Check for a vacuum leak around the throtle body and intake manifold.
you have brake fluid leak in your brake system somewhere that need to be check.
a small evap leak would not cause your car to jerk.
you have to find where the leak is first.