I installed a cat back exhaust w dual 3" pipes on my 99 Chevy Silverado (4.9 V8) and new slotted and drilled rotors 2 weeks ago. They did some mods to the exhaust to fit it to my truck. Now I’ve gone through 4 master cylinders since. I never had master cylinder problems before. Brakes Plus did the work, but they’re stumped by what’s going on. It will be ok for a few days, then suddenly start leaking all its fluid out. I keep losing my brakes at the worst possible moments, always on a hill. Any ideas would be really helpful. This is my only vehicle.
I think you have one for the record books,this is going to take eyes on to fix.
I would suspect something Brakes Plus is doing (like an installation error or wrong part)
Leaks, but where? That info is needed to attempt to help you.
Where on the master cylinder is it leaking it’s fluid out at?
I would suspect the power brake booster has failed if the leaking is coming from the seal between the master cylinder and the brake booster.
You do still have the check valve on the vacuum line between the brake booster and the engine, correct?
Did they remove a heat shield or is headers running hotter that old exhaust?