I'm trying to figure out if I have a leaking master cylinder or a leaking brake line in my 68 Riviera ...The master cylinder will be empty if the car sits over night but if i top it off and pump the brakes , it will work just fine for the rest of the day and I have new brake drums and wheel cylinders ..So is it a leaking master cylinder or rusted brake line ?
If its leaking that bad, you should see a area that soaking wet someplace. With that much loss, there should be a puddle under the car! Is it wet at the back of the master? Leaking out the back and running down the power booster? My best suggestion would be to put the car on jackstands and pull all 4 wheels for a thorough brake inspection. Inspect all the lines for corrosion, peel both dustboots back on each wheel cylinder and compress each end to make sure they are all free. If you cant, or don't have the resources to do that. bring it to a competent mechanic. Don't drive the car until you get the brakes sorted out
If you don't have a puddle on the floor it's probably soaked in to your carpet. How many times have you gone thru this cycle?
