Hi, I am new here. First post. I have a 1954 GMC 1.5 ton. I replaced all my wheel cylinders and master cylinder, ordered all new parts and rebuilt my hydrovac, adjusted shoes, and bleed the complete brake system. I drove the truck a couple times and the brakes were good. I let it sit a couple weeks and had no brakes, master cylinder was now empty. i checked all lines and bleeders for leaks and couldn't find anything. re-bleed everything again, and the same thing happened. empty master cylinder. I removed the hydrovac, and expected to find the power cylinder assembly full from an internal leak. It was empty. Can someone give me some pointers on where I am losing brake fluid? Thank you.
