Hy smokinjoe3, there is a basic test for the Hydrovac function, before you start the truck jump in and pump the brake pedal a couple of times, now press and hold the brake pedal and start the engine, if the Hydrovac is working you should feel the brake pedal move closer to the floor once the engine starts. If the brake pedal does not change you have a Hydrovac problem. I don't want to sound negative but you could be dealing with multiple problems, seized wheel cylinders, delaminating flexible brake lines, internally corroded steel brake lines, at this point I think a complete overhaul of the braking system would be the wisest move, but do the Hydrovac test first and let us know what you find, good luck
