Coolant leak bottom front of 2010 f150 5.4 no overheat

If the liquid is clear in colour and has no smell it is unlikely to be coolant in a 2010 vehicle. Is there oil floating on top of the coolant in the expansion tank? Is there a 'Mayonnaise' like build up inside the oil filler hole? These are signs the head gasket is failing.
If you live in a colder part of the world condensation can form on the radiator making it look like it is leaking.
Have you examined the radiato with the engine running at working temperature? The coolant system does work as a pressurised system and some leaks will only show up when the engine is working hard.

The big question is it overheating because of coolant loss (a leak or leaks) or is the overheating caused by a jammed thermostat, blocked radiator or the cooling fan not working.
This is the confusing chicken-and-egg situation that often faces the diagnostician, especially as when checked the coolant level is likely to be low in both cases and overheating can create coolant leaks...
Furthermore when an older engine overheats a lot or boils it can begin a chain of events that causes great expense and inconvenience over an extended period of time...

In your case it would seem the coolant is low because of a leak and that is what caused the overheating. Clearly you need to trace the leak and I can be of little help in the matter other than to suggest a hose can fail at any time and although regular inspections can greatly reduce the chances it can't entirely eliminate the possibility. Water pumps on the other hand, often aren't accessible for inspection without removing lots of stuff but they are generally very reliable and tend not to suddenly start gushing coolant. Most often they are responsible for a minor mystery coolant loss that gradually gets worse over an extended period.

I am wondering if the previous owner could have known something about the problem.

Locating the leak would generally mean getting under the car and removing any undershield components in order to narrow the area of the leak and then remove any further components until eyes can be rested on the actual source of the leak.

First I would look at all the hoses for pinhole leaks. The test the water pump by trying to move the radiator fan back and forth(on a longitudinal engine, not transverse). Turn on the engine and see if there is any coolant leaking from the front of the coolant pump. If so, the coolant pump is going bad. Otherwise, can you smell the sweet smell of coolant in the cab? If so, you probably have a leaking heater-core,

CAR OVERHEATING FIRST CHECK FOR LOW COOLANT IN THE RADIATOR COOLANT OVERFLOW JUG.IF COOLANT LEVEL IN OVERFLOW JUG LOW REFILL ADD COOLANT BACK TO THE FULL COLD MARK.PUT RADAITOR CAP ON COOLANT OVERFLOW JUG START ENGINE LET IT IDLE UNTIL IT OPERATING TEMPERATURE.MAKE SURE TOP RADIATOR HOSE GETTING HOT WHILE ENGINE WARM UP.IF TOP RADIATOR HOSE DONT GET HOT WHILE ENGINE IDLING YOUR THERMOSTAT COULD BE STUCK CLOSE CAUSING CAR TO OVERHEAT.IF TOP HOSE IS GETTING HOT.CHECK FOR COOLANT LEAKS CHECK TOP RADIATOR HOSE AND BOTTOM RADIATOR HOSE FOR LEAKS.CHECK FOR LEAKS AT THE RADIATOR CORES AND PLASTIC SIDE CONTAINERS.IF ALL IS GOOD ENGINE OVERHEATING WHILE IN A LONG TRAFFIC LINE, COOLANT FANS NOT COMING ON.COULD HAVE FAULTY ENGINE COOLANT TEMPERATURE SENSOR OR BLOWN COOLING FAN FUSE OR RELAY.COULD HAVE PCM FAULT.MAKE COOLING FAN ELECTRICAL CONNECTORS AND WIRING NOT DAMAGE OR BROKEN.

You may have a radiator leak. Or your coolant level is low. Using the heater is not a solution to an overheating vehicle. You can usually smell coolant and see the leak. Often times a gasket can leak mixing engine oil and coolant, decreasing effectiveness of both sytems. Check color of fluids make sure the cooloant is viscus and not sludgy.

Also check coolant fan electric connections and fuses. The fan really cools down the engine moreso than coolant. It should kick on when your engine reaches a certain temp. If it does not the vehicle will overheat.

Your radiator could be clogged or your thermostat is not opening, take your car to a radiator shop to have it looked at. Do not overheat and drive your Honda, Japanese cars, once they are overheated, their head gaskets are prone to blowing which are very expensive to replace.

First, plastic tube may be the overflow vent from the coolant bottle.Check to see where the attached end goes. You are going to have to check engine for coolant leaks (carefully refill system without spilling anything, then look for dripping anywhere. Look for leaks from all hoses, fittings radiator, water pump etc) After checking for leaks, start it up and check again (watch where you put your hands though) While running, check that the fan comes on when the vehicle reaches operating temp.(no fan, check fan motor, sensor & relay) Turn the heat on (does it have heat?) Check temp of lower hose and upper hose. If overheat happens, is lower hose still cold? (likely bad thermostat). If you found a leak, replace whatever is leaking...best insurance is to change thermostat after any overheat. Last, is there any white smoke from tailpipe, does engine run rough? If so, could be a failed head gasket or crack in cylinder head. (at this point last thing to worry about unless there is excessive smoke or rough run or oil in radiator or coolant in oil).

You have a coolant leak most likely in the heater core. Try disconnecting your heater hoses and coupling them together, then running the engine to see if the leak goes away. If it does, I would have the heater core replaced.

is it gushing out of the pressure cap on the radiator or coolant reservoir? if so its possible the head gasket is on its way out. when you start the vehicle is there any white smoke/steam coming out of the exhaust it doesn't have to be a cloud.
If you fill the system then run engine, let it get warm and leave the hood open, switch off engine and stand well back and try and see where the water comes out of.

If you smell coolant then there is a small leak, it is most likely the water pump shaft seal, look for stains, coolant leaves a white powder when it dries, look on the underside of the hood for any coolant stains from it been flung there by the spinning water pump. Also have a radiator pressure test run, good insurance aginst an engine overheat if leak worsens, engines are very expensive to repair if overheated badly.