After 6 years of neglect, my 70 LT1 is ready to come off the jackstands. I had a leak at the left rear caliper where the two halves come together. This caused the rear master cylinder reservoir to leak down. I bench bled the master cylinder and reinstalled (not power brakes). I then proceeded to bleed the brakes, starting at the left front. I keep getting large quantities of air, and it is not from my bleed set-up. The mighty vac holds vacuum fine before opening the port, and the vacuum does not fall rapidly during the bleed, althought it does fall. I decided the try to pump the brake pedal a few times to build up some pressure in the system, and I get no resistance. The leak at the rear calliper is about a drop a minute, maybe a little slower. Overnight, the rear reservoir has lost less than 1/16th inch of fluid. I put a clean towel on the rear caliper around the leak and pressed the brake pedal 50 times, with no fluid squirting out. I can find no other leaks. Why can I not develop any pressure with the pedal? I just went out and checked again, I got 1 drop as I was writing this. Thanks for the always expert advice. This and installation of the exhaust and tires are all that remain before finally lighting this beast back off.
-
-
Re: C3 Brakes, no pressure
Jeph are you closing the the bleed valves when you are trying to build up pressure? A try this method is loosen the brake line to the rear system enough that when a helper will push down on the brake pedal and test for fluid flow? If your master cylinder is original it will have bleeder valves on the left side to check. -
Re: C3 Brakes, no pressure
All bleed valves are closed, and I rechecked for any leakage there.
The master cylinder is not original, no bleed valves on the MC.
I loosened the output line from the rear MC resevoir about half way (no staic leakage). When I pressed the brake, I got fluid from around the fitting. I tried the same proceedure with the front, and got a good stream past the fitting.
I do have my original master cylinder, still in the box from overhaul by White Post (top notch). I'm heasitant to throw good parts at an unknown problem, though.Comment
-
Re: C3 Brakes, no pressure -> solved
Because the test Jim suggested seemed to show a discreapncy in output pressures between the front and rear resevoirs, I re-bled the master cylinder. Sure enough, I got a big slug of air out of the rear. So, the cause was just me being sloppy. I now have brake pressure again. Thanks for your help Jim. Now I just have to rebuild my rear brakes...Comment
Comment