Fluid is leaking from the front of the engine, but no hoses seem to be leaking. The car does fine, then I notice the temp gauge needle has pegged on hot. I add 3/4 of a gallon of water and things are fine for a day or two. I live in very mountainous El Salvador. What gives with the fluid leak? Water pump? Gasket?

Is this a ford ? Don't know of any other car maker using cylinder head temp sensor ! Is the cooling system full an no air ? probably a gauge problem !

You could replace the sending unit to cross it off the list of possible problems.
You could check resistance cold and then with the engine at normal temp too. The gauge on the dash could be faulty too.

It sounds like you have a couple of issues here, so lets start with the transmission one first. What it sounds like is that you have a busted hose, and the good news is that it is not expensive to repair. You will need to get under the vehicle and find the hose or hoses that are leaking and cut a piece of each hose off so that you can take it to the parts store and get the correct hose to replace it or them. I would recommend getting new hose clamps as well to re-attach the hoses. It also seems that you have some type of radiator leak if your vehicle is running hotter than usual. The leak could be a slow one and that could be the reason that it went un-noticed. The reason that the heater is not working even though the cars engine is hot is that the water that is used to cool the engine is scalding hot and that hot water flows through your heater core and that is how heat can be selected and blow hot air out of the vents. If there is not enough water, then there will not be any heat. This is some thing that you will also want to address immediately as if the engine runs hot due to a lack of water/antifreeze then you will run a high risk of damaging or blowing the motor and that would not be good. My advice is that you locate the cooling system leak and fix it ASAP to avoid some costly damage. A lot of cooling system leaks are, the water pump, radiator cap or bad hoses, so make sure that you check them thoroughly. I hope that you have found this information helpful as that is my goal.

Make sure your battery is charged fully and the terminals are very clean. Get a free stress test at a parts store. If you have a charger, connect it up and see if that solves the problem. Voltage levels that might allow the car to start and run fine may be low enough to cause electronics problems with radios, gauges and locking mechanisms.

they are designed not to fluctuate with engine temp and are kept stable once operating temp is reached. only if the temp exceeds a set mark will the needle rise to indicate overheating,

try changing the thermostat or you have a block somewhere try flushing it out with a garden hose

Your overheating problems can have several possible causes.
1) Airlock in heating system - solution - bleed air from cooling system. Method is dependent on make/model of vehicle
2) Radiator blocked - solution - drain and flush radiator
3) Failed waterpump - solution - fit new waterpump
4) Engine thermostat stuck in closed position - solution - fit new thermostat
5) Electric cooling fan (if fitted) failing to operate - solution - check fan, fan operating switch, all wiring and connectors
6) Not enough coolant in system - solution - check and top up to required level. Also check all hoses for sign of leakage.
7) Faulty temperature gauge giving incorrect reading

most likely, replace thermostat .

Jess, Make sure you don't have the ground and sender level circuits crossed at the gauge. If the needle is pegs to full it indicates an open circuit, if the needle pegs to empty it is indicating a short to ground.
Let me know.
Regards,

Warm the engine up to operating temperature. Does the upper radiator hose get warm? If no, then cange the thermostat. If yes, then the thermostat is working fine. On the thermostat housing, there is a sensor. Some engines have 2 sensors. One goes to the computer and the other goes to the temp needle in the dash. Unplug the harness and put a jumper wire in the harness. Turn the key to on, and see if the temp needle goes up. Which ever harness causes the needle to go up, replace that sensor. Hope this helps.