I just remembered my bronco also runs really hot like my thermostat is going bad. The needle is always at 3/4 to full hot then drops just a tiny bit when it goes to full. Im planning on replacing the thermostat next weekend. Will this possibly solve the issue also? But I am still going to look into something for overflow. My dad has a 77 ford and 79 ford supercabs that im going to check out how they are set up tommarrow. possibly steal something off his if need be =P
Do the Basic checks asap before engine components are damaged
Damaged water pump
Cooling fan inoperative (check belt, etc. check fan clutch for fluid leakage. If the fan spins more than five revolutions when turned by hand, the fan clutch mechanism should be replaced. Faulty fan clutches are a major cause of overheating)
Check hoses, clamps, radiator. Examine the hoses, clamps, and the radiator and cap. Repair or replace if necessary.
If engine is hot, allow engine to cool down before proceeding.
Remove radiator cap & check coolant level @ radiator
Check coolant for contaminants such as rust or corrosion. Also, check for color discoloration
Visually inspect A/C condenser core (if equipped) & radiator for obstructions, such as leaves or bugs.
Allow engine to run for 10 minutes.
Feel the inlet and outlet heater water hose and the underside of the upper radiator hose
Are the upper radiator hose and heater water hoses cold?
Yes - REPLACE water thermostat.
No - LEAVE engine RUNNING
Check for proper cooling fan clutch operation
Did cooling fan clutch operate OK?
Yes - CHECK the following:
Rust or scale in radiator
Water pump shaft and impeller (leaks, shaft is loose
Collapsed lower hose
No - REPLACE fan clutch
Do a Pressure Test - tester is available for rent (money back if returned as given) @ many parts stores.
While you are checking the coolant level, check the radiator cap for a worn or cracked gasket. It the cap doesn't seal properly, fluid will be lost and the engine will overheat. Worn caps should be replaced with a new one.
At least once every 2 years, the engine cooling system should be inspected, flushed, and refilled with fresh coolant. If the coolant is left in the system too long, it loses its ability to prevent rust and corrosion. If the coolant has too much water, it won't protect against freezing.
The pressure cap should be looked at for signs of age or deterioration. Fan belt and other drive belts should be inspected and adjusted to the proper tension. (See checking belt tension).
Hose clamps should be tightened, and soft or cracked hoses replaced. Damp spots, or accumulations of rust or dye near hoses, water pump or other areas, indicate possible leakage, which must be corrected before filling the system with fresh coolant.
to check the operation of a thermostat place it in a pan of boiling water. If it does not open more than 1/4 inch, do not install it in the engine.
Removal & Installation in 78-79 351M & 400M; "...Drain the cooling system below the level of the thermostat. Use the petcock valve at the bottom of the radiator to drain the system. Disconnect the vacuum hose connector from the PVS valve located on the thermostat housing. Remove the upper radiator hose. Remove the thermostat housing retaining bolts. Remove the gasket and thermostat from the block and clean both mating surfaces. Position a new thermostat in the recess in the block with the spring side down. Coat a new gasket with water resistant sealer and position it on the outlet of the engine. Position the thermostat housing onto the mounting surface of the outlet. Torque the bolts to 25 ft. lbs. Install the upper radiator hose. Connect the vacuum hose. Fill the radiator and operate the engine until it reaches operating temperature. Check the coolant level and adjust if necessary..."
Fan & Clutch Parts Break-Out Diagram in 78-83 351M, 400M & 460
Water Pump Removal & Installation in 78-79 351M, 400M & 460; Disconnect the battery ground. Drain the cooling system. Remove the bolts securing the fan shroud to the radiator, if so equipped, and position the shroud over the fan. Remove the fan assembly. Remove the fan shroud. Remove the accessory drive belts and water pump pulley. Remove the alternator and brackets. Remove the compressor and bracket and lay it aside. DO NOT disconnect the refrigerant lines! Remove the power steering pump and brackets. Lay it aside. DO NOT disconnect the fluid lines! Disconnect the heater hose and lower radiator hose from the pump. Remove the bolts securing the water pump to the engine and lift off the water pump. Clean all gasket mounting surfaces thoroughlyInstall the water pump in the reverse order of removal, using a new gasket coated with sealer. Torque the bolts to 12-18 ft. lbs. Install all remaining parts in reverse order. Fill the cooling system, start the engine and check for leaks.