Have yall ever had mystery brake fluid loss? My 95 5.2 is just a secondary vehicle these days, noticed the larger reservoir for the front brakes was low when I filled it last year some time, it was still above the min mark, probably a little below halfway full, I didn’t see any wet spots, cranked the truck up, pumped the brakes 10 times and rechecked and still nothing. Had a wheel cylinder blow on an 01 v6 I had years ago but that took all the fluid very quick with it so I don’t know if it’s that. I read the master cylinder can have a hidden leak where it connects to the brake booster, honestly the only thing I can think of. I topped the fluid off and only drive it slow in town if it’s ever used but just wondering if there’s anything I missed maybe. I heard about a supposedly common brake line failure point on these trucks near the gas tank but I didn’t see any wet spots or fluid around it at all, kinda stumped, next weekend when he’s free I’ll borrow my dads jack to check both rear wheel cylinders…the truck sits high enough to work under so I never bought one for it lol. I’m in Tx so there’s only very very light surface rust if anything on the old truck, nothing like I see on YouTube of rust damage. Just stumped. ONLY the larger reservoir for the front brakes was low, the smaller reservoir for the back brakes was still perfectly full

 

The line that goes to the rear brakes is shielded by the gas tank and prone to rot. Check along that frame rail. My truck ate two of them. Now all stainless pre bent.
Cameras on a cable are great for that sort of stuff.
All of your rubber lines if original are at the thirty year mark, just a thought. I would also check the master cylinder

 

As your front brakes wear, the fluid level will go down as well.

 

Fluid can leak past the rod seal into the booster.

 

thanks so much guys, yeah, another person actually told me it could be the pads wearing out, it doesn't make any noise when braking and I felt with the wheel still on and on the front side that's accessible there's still a bit of room before the metal noise alert scraper pad would make contact with the rotor, truck seemed to still stop alright, about the same as it has when I drove to town the other day in it. I looked again under the truck and the hoses look ok for the brakes and lines too, all bone dry, it either has to be the pads or hidden where the master cylinder connects to the brake booster at the back, no visible leaks from the master cylinder. I was surprised how cheap a pads and even new rotor combo set was online, may just order some in the near future

 

If you can top off the fluid, and it doesn't immediately go down again, and your brakes stop the truck good, pedal feels good, then you likely don't have a problem.