How do I remove the fan clutch to replace the water pump on a 1985 F250 6cyl 300 cu in?

To be able to replace the bybass hose on the water pump, you must first make room to gain access to the hose clamps that attach to the water pump. To make room you must first remove the fan clutch, fan and fan shroud all of them simultaneously.
To do that, start by loosening the tensioner roller with a rathcet and removing the serpentine belt. Then loosen the fan cluthc nut using a 32 mm spaner and loosen the bolts of the fan shroud. Then pull the three things upwards (fan shroud, fan, and fan clutch).

special tools you need EN 48543 FAN CLUTCH HOLDING TOOL. J41240 FAN CLUTCH REMOVER AND INSTALLER. TORQUE FOR FAN CLUTCH NUT 41 LB FT. FOUR BOLTS TO FAN BLADE TORQUE 20 LB FT.WATER PUMP BOLTS TORQUE TO 11 LB FT. DONT NEED SPECIAL TOOLS REMOVE WATER PUMP.

The water pump is directly behind your fan clutch. Most probably, it's the pump. Shaft seal is already worn out (maybe because of damage bearing). You have to replace the whole assembly or replace the shaft, seal, and bearing. These items are within the repair kit that you can buy in parts store.

you need to remove the fan blade and clutch assembly as one with the big nut between the fan and water pump it turns op of engine big wrench and hit with dead blow hammer

If you need further help, I’m available over the phone at https://www.6ya.com/expert/mike_9693b5ad75773352

TO REPLACE WATER PUMP.REMOVE THE RADIATOR SHROUD HALVES.REMOVE FAN CLUTCH AND FAN.YOU NEED FAN CLUTCH WRENCH AND A FAN CLUTCH PULLEY HOLDER.YOU CAN RENT TOOLS AT AUTO ZONE OR BUY THEM AT A AUTO PARTS STORE.THE FAN CLUTCH BOLTS ARE LEFT HAND THREAD. REMOVE THEM BY TURNING CLOCKWISE.BEFORE INSTALLING NEW WATER PUMP COAT BOTH SIDES OF WATER PUMP GASKET WITH GASKET SEALER.TORQUE WATER PUMP BOLTS 18 FT LBS.

Assuming this is a 460 Ford Big Block:

REMOVAL

-Drain cooling system.
-Remove drive belts.
-Remove bolts attaching fan shroud to radiator.
-Remove fan blade from fan clutch and remove fan shroud.
-Remove fan clutch and water pump pulley from water pump.
-Remove four bolts and one nut attaching A/C compressor mounting bracket to cylinder head and water pump. Do not remove A/C compressor or power steering pump from A/C compressor mounting bracket.
-Pull A/C compressor mounting bracket forward to remove from stud on water pump.
-Remove bolt attaching generator adjusting arm to water pump. Remove four bolts attaching generator mounting bracket to cylinder head, cylinder block and water pump.
-Remove remaining water pump attaching bolts and remove water pump from engine front cover.
-Remove water pump cover from water pump. Discard water pump housing gasket and water pump cover gasket.
INSTALLATION
-Remove any gasket material from water pump cylinder front cover and separator plate mating surfaces.
-Position new water pump housing gasket and water pump cover gasket coated on both sides with Perfect Seal Sealing Compound B5A-19554-A or equivalent water-resistant sealer meeting Ford specification ESE-M4G115-A.
-Position water pump and water pump cover onto engine front cover. Install bolts and tighten to16-24 Nm (12-18 ft. lbs.).
-Install generator mounting bracket to cylinder head, cylinder block and water pump with four attaching bolts. Install generator adjusting arm to water pump with one attaching bolt. Tighten 7/16-inch bolts to 54-71 Nm (40-53 ft. lbs.) and 3/8-inch bolts to 41-54 Nm (30-40 ft. lbs.).
-Position A/C compressor mounting bracket over water pump stud and secure to cylinder head with four bolts tightened to 54-71 Nm (40-53 ft. lbs.) and secure nut to water pump to 41-54 Nm (30-40 ft. lbs.).
-Install water pump pulley and fan clutch to water pump hub with four bolts. Install fan blade to fan clutch with four bolts. Tighten water pump pulley, fan clutch hub bolts, and fan-to-fan clutch hub bolts to 16-24 Nm (12-18 ft. lbs.). Install fan shroud.
-Install drive belts.
-Fill and bleed the cooling system.
-Start the engine and check for leaks

If their is one large nut between the fan and pump then look for notches in the side of the sharp edges of the nut. If they are there then it is lefthand thread.

The text below is from the GM Service manual 4.3L V6 Engine
Water Pump Replacement (4.3L)
Removal Procedure
Drain the cooling system. Refer to Draining and Filling Cooling System .
Loosen the water pump pulley bolts.
Remove the cooling fan and clutch assembly.

Tools Required
J 46406 Fan Clutch Wrench

Removal Procedure
Remove the upper fan shroud.
Remove the fan clutch from the water pump in a counterclockwise direction using the J 46406 .
Remove the fan clutch assembly.
Remove the drive belt. Refer to Drive Belt Replacement Remove the water pump pulley mounting bolts.
Remove the water pump pulley.
Remove the radiator outlet hose clamp from the water pump.
Remove radiator outlet hose from the water pump.
Remove the water pump mounting bolts.
Remove the water pump from the engine.
Remove the water pump gaskets.
Clean the water pump gasket mating surfaces.
Installation Procedure
Install the water pump gaskets.
Install the water pump to the engine.
Apply a sealer (GM P/N 12346004) to the bolt threads.
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Install the water pump mounting bolts.
Tighten
Tighten the mounting bolts to 41 N·m (30 lb ft).
Install the radiator outlet hose to the water pump.
Install the water pump pulley.
Install the water pump pulley bolts.
Tighten
Tighten the water pump pulley bolts to 25 N·m (18 lb ft).
Install the drive belt. Refer to Drive Belt Replacement in Engine Mechanical - 4.3L.
Install the fan clutch assembly.
Fill the radiator cooling system. Refer to Draining and Filling Cooling System .
Inspect the cooling system for leaks.

Was the thermostat put in backwards? I know this is a silly question, but I've seen it happen. The water pump will fight it if it is. Another thing are the coolant passages, are they flushed out? Also, if that fan clutch is the original one, I would go ahead and replace that as insurance against the water pump breaking.

it is pressed onto water pump..will not come off when you remove fan clutch