How do you replace the heater core in a 1992 Ford Ranger STX V-6 4.0?

This is a re-badged Ford ranger so watdh the video of rthe ranger heater core change out. How To Replace Heater Core On Ford Ranger

Your heater core could be plugged. If you have an air compressor, you can try removing the heater core hoses from the firewall and blowing some air through to unplug it. This worked for me before.

Is the leak under the dash ?

Have you checked the positive and negative connections at the battery, and are you getting voltage at the starter and solenoid when the key switch is in the start position ?
Have you checked the clutch safety switch ?

No problem,shift to 4wheel while not moving.Your clutch has an adjustment.

no...that would effect running temperature. I would guess a clogged heater core or hose would be more likely than that. First, check the actuator on the input line to the heater core. As I recall from my '92 Ranger, it was actually vacuum driven. First step would be to make sure the vacuum line (or control wires if it's electric) is attached. If everything looked good, I would pull the valve off and apply vacuum (or voltage if electric) and see if it is actually opening. Beyond that, it may be that the heater core is clogged. Remember, the heater core is just a small radiator and the same calcification / sludge that builds up in radiator passageways causing them to clog do the same inside the heater core.

Old rule of thumb highest hose to top heater core inlet.

the dash must come out.

how do I change the heater core on my 1992 ford ranger
it had a short and cot on fire, put out and drove off, need to replace

allow the system to cool down

take radiator cap loose to release pressure

once pressure is released tighten cap

loosen clamps on the heater hoses in the engine compartment on the pass. side of firewall.

plug or cap off the heater core tubes to prevent spillage when you pull it into the truck

place a trash bag on floorboard in case spillage occurs

remove the five screws holding the heatre core access cover, three on top and two on bottom

carefully pull heater core back and down and remove it from the dash

install is reverse

Hope this helps