I have an older model ford f-800, I think its about a 86 model. It has hydraulic brakes and I'm guessing hydraulic parking brake. I need to find out how to release the parking brake without the engine running. I'm guessing again that the engine turns the hyd. Pump that controls the Parking brake. Thank you
that year model had Lucas Girling or Boker brake system on it, they are the same just different names, It was not one of Fords better ideas. It does in fact rely on a hydraulic pump driven off the engine, however it should have an electric motor mounted on the bottom of the booster assembly that cycle briefly when the key is first turned on, this will allow you short sessions to move it, but you have to hold the park brake button in with key on, and it is only good for short time spans. I never cared for the way that those systems integrated a wedge type brake system with a semblance of a hydra boost system. pains to work on.
There's a caging bolt in the center of that Durapark brake chamber, takes a 3/4" wrench. Can't remember if you turn the bolt CW or CCW, but it pulls the wedge out of the brake cylinder and releases the parking brake. Make sure you have the wheels chocked before doing this.