Brake lines have air and go all way to the floor brake fluid gets on top off filter instad of staying under add brake fluid every two days

and start off at the caliber farthest from the master cylinder. usually right rear. If your peddle stays rock hard there's still still air bubbles in the hydraulic fluid an your lines.

brake fluid goes in the reservoir on top of the clutch master cylinder. If there is no reservoir check for a line to the brake master cylinder reservoir as some cars use the brake master cylinder reservoir as a common unit . Check that that reservoir is full. Bleed out the slave cylinder to remove air in the system.

check the backside off all wheels.you problably have a leak.

When that happins the system is low on fluid (brake fluid) you might have a leak at the brake master cyl. or the slave cyl. on the transmission, check the fluid lines for leaks, add fluid and bleed the air out of the system.

look under the back of your truck. there should be a steel line running from each brake cylinder to a splitter about midway down the axel. there should also be a metal line running from the splitter to the fluid reseviour in your engine compartment. to remove the lines: find the proper size wrench. loosen and remove the line. replace the line with a new one. tighten it up. you will have to add more fluid to the resivour (dot 3 brake fluid) afterwards. now you "bleed" the brakes to remove the air from the lines (air in the lines causes squishy, and uneven brake opperation.) to bleed the brakes: get a friend. this is a 2 person job. one of you get in the cab (person 1). the other under the truck by the wheel that the new line was put on (person 2). there will be a little valve poking out of the back of the brake just above or beside the brake line. now: person 1 = (1), person 2 = (2) have (1) step on the brakes hard and hold them. (2) open the bleeder valve until (1) yells "FLOOR!" (this means that the brake petal has gone all the way to the floor.) as soon as (2) hears "floor," close the valve. next (1) pumps the brakes 3-4 times to build up pressure. (2) open the valve again and then close it when (1) hollers. repeat this procedure until only brake fluid comes from the bleeder valve. you will see air sputter out as well for a few goes. once the air is removed from the lines, refill the resiviour with fluid. put the cap back on. then your good to go.
note: be carefull when opening the valve. the fluid can shoot pretty far. also make sure that you do it where you don't mind getting plenty of fluid on the ground. and remember, brake fluid will discolor clothes and any other cloth is comes in contact with.

If the brake master cylinder reservoir is full of brake fluid, and you haven't had to add any recently, then you probably don't have any air in the lines but may have a bad master cylinder that isn't capable of building up fluid pressure. If you've had to add brake fluid recently because the system was low or empty then you may have both air in the system and a leak that is allowing brake fluid to escape. Possible spots it can leak are at brake hoses, brake lines, wheel cylinders, and brake calipers, just to name a few. Either way, don't attempt to drive a vehicle without good working brakes as it is very dangerous to do so. I would have a good shop check this one out and give the entire system a thorough checking over to find out what has gone wrong. Good luck, hope this helps a bit.

A bad brake master cylinder will cause the pedal to go the floor.

You need a new master cylinder. I'm assuming that you aren't losing brake fluid from a leak somewhere.

As the master cylinder wears out it's internal seals allow fluid to leak past the pistons. None actually leaks out of the brake system so you don't see the leakage on the ground under the car and the brake fluid level remains constant.

Replacing the master cylinder is not hard from a technical standpoint but it is a job you'll want a service manual's help with just so you know the proper steps to take. A small, hand operated, vacuum pump is a godsend when you get to the part of bleeding the brakes and this is a good time to flush the brake lines anyway. Proper tools are a must, get a proper line wrench to avoid damaging the brake lines when you remove them from the master, and be careful when reinstalling the lines that you don't start them crooked and cross thread the line fittings.

A good quality rebuilt master cylinder will do the job, or you can spring for the new factory part. Back in the day we used to rebuild them but finding a rebuild kit is impossible these days.

power steering reservoir is the green cap that is attached to the battery box.

To add more brake fluid, the container is located under the air filter. You have to take off the air filter to get under enough to get to it.

sounds like a rear wheel cylinder