Have a 83 f350 dually XL and replaced unit that operates clutch system useing brake fluid system ,was i suppose to replace something else? or is it just alot of pumping and bleeding air out of the brake lines?

This sounds like the hydroboost unit is leaking.behind the master cylinderThe braking system on this using the power steering pump to provide power assisted brakes instead of a brake booster. The hydroboost unit most likely needs replaced.

FIRST REMOVE ALL OLD FLUID FROM CLUTCH MASTER CYLINDER YOU CAN USE A SIPHON YOU HAND PUMP.AUTO PARTS STORES SELLS THE HAND PUMP SIPHONS. THEY DONT COST MUCH AND KEEP FROM MAKING A MESS.SIPHON OUT MUCH AS YOU CAN THE OLD FLUID IN THE CLUTCH MASTER CYLINDER.THEN POUR IN THE NEW FLUID DOT 3 BRAKE FLUID IN CLUTCH MASTER CYLINDER.OKAY YOU NEED A HELPER.LOCATE THE SLAVE CYLINDER.REMOVE SLAVE CYLINDER HOLD SLAVE CYLINDER 45 DEGREES WITH BLEEDER SCREW LOCATED AT THE HIGHEST POINT.HAVE A SMALL DRAIN PAN UNDER SLAVE CYLINDER.HAVE HELPER FULLY DEPRESS AND HOLD THE CLUTCH PEDAL THEN OPEN BLEED SCREW.CLOSE THE BLEED SCREW AND HAVE HELPER RELEASE THE CLUTCH PEDAL.REPEAT THIS PROCESS UNTIL ALL THE OLD BRAKE FLUID AND AIR BUBBLES LEAVES THE HYDRALIC SYSTEM AND WHEN YOU CAN SEE GOOD STREAM CLEAN FLUID NO BUBBLES YOU HAVE GOOD SOLID CLUTCH ALL IS GOOD.MAKE SURE THROUGH THE BLEEDING PROCESS YOU DONT LET CLUTCH MASTER CYLINDER RUN DRY OR YOU WILL HAVE TO START OVER.KEEP CLUTCH MASTER CYLINER FULL BRAKE FLUID WHILE DOING THE WHOLE BLEEDING AND FLUSHING PROCESS.

I have the same problem,, put all new brake components on truck, needed it anyway,, found out that the booster is not designed for a diesel application,, ford made a model change for the diesel,, number from ford is F 5 T Z - 2005 CA a zero loss booster,, have ordered on will put on when arrives, $240. good luck,,

Unfortunately you will have to remove the axles on that model of truck to access the brakes and it is necessary to replace the seals at this time because you will probably cut the old seals upon removal.I would recommend that if you are going to check them you at least need to clean and de glaze the old shoes if you don't replace them!!!! make sure to use a good quality brake cleaner.

Rear To Remove:

1. Remove the brake master cylinder filler cap and remove fluid until the reservoir is half full.
2. Raise and safely support the vehicle.
3. Remove the rear wheel and tire assembly. CAUTION
   Never allow the brake caliper to hang from the brake hose.
   
4. Remove the two disc brake caliper pin bolts.
5. Lift the disc brake caliper from the anchor plate and position the caliper out of the way. Do not disconnect the fluid line.
6. Inspect the disc brake caliper for leaks and replace the caliper if necessary.
7. Remove the pads and retraction clips.

To Install:
CAUTION
Do not allow grease, oil, brake fluid or other contaminants to contact the pad lining material.

1. Install retraction clips.
2. Install the brake pads.
3. Slowly compress the caliper pistons with a large C-clamp. CAUTION
   Use care not to damage the bleeder screw or front disc brake rotor shield.
   
4. Install the disc brake caliper.
5. Install the disc brake caliper pin bolts. Tighten the pin bolts to 26 ft. lbs. (35 Nm) (F-250, F-350 SRW). Tighten the pin bolts to 56 ft. lbs. (76 Nm) (F-350 DRW). Tighten the pin bolts to 46 ft. lbs. (62 Nm) (F-450 F-550).
6. Install the wheel and tire assembly.
7. Lower the vehicle.
8. Fill the brake master cylinder reservoir with DOT 3 motor vehicle brake fluid.
9. Inspect for correct brake operation.

Check the fluid level in the reservoir for the slave cylinder, or look underneath to find a leak. If the reservoir is empty then you need to replace the clutch slave cylinder. A quick fix is also try to bleed the clutch slave like you would bleed brakes, open the bleeeder push the pedal down and hold it until the bleeder is closed, repeat until solid fluid comes out...will take 2 people.

Do not put oil in this system.It uses brake fluid in the reservoir.If the system doesn't have any fluid in it, there is a leak, and both the clutch master cyl and the clutch slave should be replaced. They both were used the same amount of times, and wear evenly. When you add fluid, the clutch master cyl compresses the fluid down the line/hose into the clutch slave cyl. This depresses the clutch fork/arm and disengages the clutch disc so the input shaft into the transmission stops moving, allowing the trans to be put into gear. LOOK FOR THE FLUID LEAKING TO ISOLATE THE PROBLEM. This is a closed system, and the fluid never gets used, unless there is a leak.

you must have a leak in your brakes! check your brake fluid! They may work for now but after all your brake fluid is pushed out they wont work. You better take a look underneath and get someone to press on the brakes to see where it is leaking out. You can keep toping up the brake fluid and that might get you by for a while.

Adjust your rear brake shoes. Then rebleed the system. Start at the master cylinder Bleed master first then the wheel furthest away from the master (right rear then left rear then right front then left front. Do that and your pedal should be good.

5 Inspect Brake Fluid Type Brake fluid loss or contamination 10 Inspect Master Cylinder (Brake System) Worn or leaking brake master cylinder. 11 Inspect Brake Power Booster Damaged booster vacuum line/check valve, or diaphram