2000 ford ranger 3.0 v6 engine.coolant being forced into the reservior and both top and bottom hoses at radiator are collapsing.i have replaced the thermostat.whats could be problem

Do you have the right mix on the coolant you have in the engine? Could you have trapped air in the coolant system, did you have the heater system on when you were filling up with coolant. I assume you changed the radiator cap when you replaced radiator. I guess it could be caused by headgasket, are you loosing coolant, does oil look milky or oil in coolant. Belo link list a few things to look at but you have addressed most of them.
Ford Ranger Overheating (repairpal.com)

How to Replace Radiator Cooling Fan and Clutch 90-04 Ford Ranger V6 4.0L - YouTube

fan clutch good or bad? ' The Ranger Station

Hi , it sounds like you have caused a vacum i.e. not enough water in the system. You have to check you car when the engine and water has cooled down. The expansion tank is were the water level has a line you must fill it up to the level line with water when the engine is cold. And when its cold weather you have to use antifreeze to top up the level.

The procedure is fairly generic on the Ford and other non-transverse engines. First think of direction of coolant circulation. In radiator, coolant flows under gravity (and negative pressure as will be seen) to the bottom radiator hose and through it to the intake of the water pump. (The pump is directly aft of the fan with the vibration damper and accessory belt drive pulley sheaves in between.) The pump then forces coolant through a port into the engine block and galleries; and also force coolant through the heater coil circuit which returns it (also) to the engine block. Under pump pressure, the speed of which is governed by engine RPM (crank rotational speed), the coolant circulates back through the coolant pump via a second engine block port until (like an 8 track tape)...until the coolant has heated (by combuston chamber heat sinking) to t'stat (thermostat)-regulated engine-normal-operating temperature, at which point the coolant flow though said engine bock recirculation port abates and is supplanted by coolant flow through the t'stat and out the engine and back to the radiator (inlet) through the upper radiator hose. So it's clear then, that where the upper radiator hose joins the engine block (near the top of the engine) there also will be the thermostat, held in place by a connector fitting or fittings to which the upper radiator hose couples on one end, and which bolts onto an engine block outlet port and flange on the other end. At that point, it is a simple matter of unbolting that coolant flow port fitting to find the t'stat squeezed in and concealed behind. Of course, you will want to have let the engine cool (to the point where upper radiator hose is squeezable), and to have disconnected that upper hose from the radiator and held it aloft to reduce spilling and then lowered to capture any spillage. (The engine having cooled, the t'stat will be closed and preventing any outflow into the hose; and the cool engine block coolant level will have have retreated under gravity to its lowest level...below the t'stat. Now that the t'stat has been removed from the hose connection flange, you will have noted beforehand its direction and orientation top to bottom...because the new t'stat must fit in the exact same manner. In case you overlooked it, those are also embossed on the new t'stat. Now remember this: each new t'stat must be installed with a new overlap seal ring, but WITHOUT any other sealant or gasket sealant material (the seal is not a gasket despite what you might read or see) and its overlap of the t'stat forms a double seal layer sufficent to contain and prevent any coolant seepage. So, now that you've clamped in the t'stat with the hose fitting and restored upper-radiator-to-engine-block hose connection, you need only to pour any captured coolant back into the radiator, screw on the radiator cap, start the engine, and bring to operating (t'stat open) temperature. Then relieve radiator pressure with radiator cap and note that coolant is circulating in the radiator. If not yet circlating, wait a while until the new t'stat opens. Finally, after engine off and cool-down, check and top the coolant level to about 1 inch below bottom of radiator filler tube.

Nothing.
The second hose is the actual overflow hose where coolant escapes should the tank become full.

Hello again Vicki, you can read my first post to you on type. Now for where and how. Put suitable container under radiator drain valve. Start to drain old antifreeze, you can also loosen radiator cap for faster drain, but make sure antifreeze doesn't start to spill all over your driveway or garage floor. When radiator and engine are mostly drained, I would recommend to change the thermostat. Follow the top radiator hose down to the engine. This is where you'll find the thermostat. Remove the attaching bolts and remove thermostat.If you wish to flush your engine,you can put water down the thermostat hole as well as the radiator cap hole, or you can do a fancy flush. Shut drain below, reinstall thermostat housing without thermostat, fill radiator with fancy flush cleaning solution and water replace radiator cap ,run for time stated on can of flush. Now you go back to where I began and start the draining again. Dispose off antifreeze correctly it is dangerous to animals if they ingest. Close drain,and fill engine with antifreeze thru thermostat housing, when almost to top install new thermostat and gasket. fill radiator almost to top, start engine, open inside heater and let engine warm to operating temperature. At this time the antifreeze level will drop, because thermostat will open, and you can fill some more .This should eliminate any possible air bubbles. Fill your coolant tank. I would like to know how you make out. GOOD LUCK.

The lower radiator hose is usually connected to the water pump. It's purpose is to draw coolant from the bottom of the radiator and circulate it through the engine and heater. a word of caution, even if you drain the radiator when you loosen the hose there will be a sizeable amount of coolant flowing from that point. Keep a pan handy!!!

1. Make sure the engine is cool.
2. Using a clean bucket disconnect the lower radiator hose and carefully drain around 1 gallon off coolant then reconnect hose.
3. Follow the upper radiator hose to the engine where it's connected to the gooseneck on the engine.
4. remove the 2 bolts holding the gooseneck and lift it up to remove the thermostat making a mental note on how it was installed.
5. Clean both sides of the gasket surfaces, install new thermostat in the same position it was removed and replace O ring(only use a Motorcraft replacement to avoid having fit issues) alternate tightening bolts until tight.
6. Refill radiatior to proper level.
7 Leaving the raditor cap off, start the car turn on the heater and let it warm up keeping an eye on the coolant level, it will go down once the air works it's way out of the cooling system.
8. Top off the system and tighten radiator cap. Check the coolant level several times during the week, there may still be some air left in the system.

A heater core transfers heat from a 1994 Ford Ranger's engine to the passenger compartment by running hot radiator coolant through a serpentine of tubing. Air blows past the hot fins of the heater core and into the truck cab.

The hoses running to and from the heater core must be removed from the engine compartment, but the core itself is accessed from inside the passenger compartment, on the driver's side next to the center console.

1. Turn off the engine, open the hood and remove the battery cable from the negative terminal. Make sure the engine is cool.


2. Attach a 3/8-inch interior diameter hose to the drain outlet on the bottom rear corner of the radiator on the driver's side, and place the bottom end in a resealable plastic container. Turn the drain valve (located above the drain outlet) counterclockwise with a pair of pliers. Drain the engine coolant into the resealable container, then close the valve by turning it clockwise. Remove the hose from the outlet.

3. Loosen the hose clamps on the radiator hoses where they attach to the heater core on the firewall. Remove the hoses.

4. Unscrew the screws holding the underdash cover in place on the driver's side of the passenger compartment. Remove the underdash cover.

5. Unscrew the four screws on the cylindrical heater core access cover and remove it. Remove the heater core by pulling it down and toward the rear of the vehicle. Replace the unit with a new heater core.

6. Reinstall the heater core access cover and screw in the retaining screws. Replace the underdash cover and screw it into place.

7. Replace the radiator hoses on the heater core in the engine compartment. Tighten the hose clamps. Add coolant until the level is between the minimum and maximum marks on the reservoir.

8. Replace the battery cable and start the engine. Check the system for leaks.

Sounds like the radiator is clogged, have the cooling system flushed, the water pump pumps water into the engine and it comes out the top hose to return to the radiator to circulate through it to cool, if the radiator is clogged the water pressure will build on the top hose, also look at the bottom radiator hose, if it collapses when you rev the engine the radiator is clogged, although sometimes the bottom hoses are reinforced with wire to prevent them from collapsing so just because they do not collapse it does not mean the radiator is not clogged.

If you need Illistration I Can Email it to you Im at
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Removal

CAUTION: Do not mix Standard (green) Coolant with Extended Life Coolant (orange). If mixing occurs, drain engine cooling system and refill with originally equipped coolant type. If this contamination occurs, the service change interval on Extended Life Coolant will be reduced from 6 years/150,000 miles to 3 years/30,000 miles.

1. Drain radiator until engine coolant is out of degas bottle. Disconnect radiator overflow hose and engine coolant vent hose at degas bottle.
2. Remove power steering oil reservoir retaining screws and position power steering oil reservoir out of the way.
3. Remove degas bottle return hose and clamp. Remove degas bottle retainers and remove degas bottle.

Installation

1. Position degas bottle in vehicle and install retaining screw and nut. Tighten retaining bolt and nut to 9-12 Nm (80-106 inch lbs.)
2. Connect degas bottle hose and clamp to degas bottle.
3. Position power steering oil reservoir onto degas bottle and install retaining screws securely.
4. Connect radiator overflow hose and engine coolant vent hose to degas bottle.