Hello ranger gang. (Finally popped my Ford cherry)
(as the title states) my 1996 XLT 4.0 V6 is leaking coolant moderately with a strong coolant smell coming through the vents Plus minor overheating occasionally I believe I'm able to rule out heater cord to the floor not being wet and no moisture on the windows. The thermostat because it hasn't overheated severely so I know circulation is happening. Pretty much other than that the engine is foreign enough to me to where I'm stumped.thank you in advanced for your insight & input!

 

Welcome to the forum

You will need to find that coolant leak first
If you smell coolant then its leaking onto something HOT, so may be evaporating before it can hit the ground under the engine, so hard to track down

You can rent Cooling system pressure testers, some auto parts stores Loan them for free but have to leave deposit.
Its basically a rad cap with a hand pump and pressure gauge attached
Cold engine
You install the cap and pump up system pressure to 20psi, system normally runs at 16psi when warmed up
Then wait and watch, pressure should start to drop because there is a leak, and because engine is cold you will see coolant dripping out of the leak point

There are also UV Dyes that you can add to the coolant, then drive it a few days
Then using UV flash light you look for the trail of dye going back to the leak point(s)

But in any case you need to find the leak

Radiators and water pumps are the most common leak points in all vehicles
4.0l OHV engine can leak from lower intake at each corner, because lower intake is aluminum and head is cast iron, the aluminum can get eaten away at the coolant passages in those 4 corners if coolant isn't changed every 2 years as it should be

4.0l OHV is also known for cracked heads, these engines WILL get a cracked head if overheated, so never let gauge get above 3/4, pull over, do not "try to make it home", let it cool off then head for home if close enough
Signs of this is white smoke from tail pipe, and bubbling overflow tank, with overheating

 

Alright then. I know my mission. Thank you very much for your help and advice. As soon as I track it down I'll let ya know the outcome.

 

So while I was changing out my starter I happened to look behind where the starters installed to see two freeze plugs there and one that noticeably was leaking coolant I wasn't able to see it before because the starter was in my way now that the starter was out I was able to locate my coolant leak! so right on! To the gentleman above who replied to the thread first if you see this what do you suggest that I do from here? And I guess it doesn't necessarily have to be that gentleman either just anyone else's recommendation? Is this going to be a massive engine teardown job or is it fairly simple

 

Replacing a Core Plug, the correct name for freeze plugs, lol, is fairly easy if you use an Expansion plug, these are "rubber" plugs

Expansion plug looks like this: https://m.media-amazon.com/images/I/..._AC_SX355_.jpg
They come in many sizes

You need to drain all the coolant first
Then you will need to remove the old rusted metal plug, you can just pound it into the block, it won't hurt anything or cause issues with coolant flow, its metal, so it will just sit at the bottom
If you can get it out that's fine too, it you use a screwdriver or drift on one edge of the metal plug it will often spin so the other edge comes out and then can be pulled out, but rusted ones are usually hard to extract that way

Clean the edges of hole and insert the expansion plug so its all the way in, tighten it up


Core plug holes are there to remove the SAND from the metal casting when the engine blocks, or heads, were make, i.e. molten metal cast into a sand mold
The metal plugs are the cheapest way to seal these holes
I assume years ago when vehicles just used water, no anti-freeze yet, these plugs would pop out if owner forgot to drain the water out, and temps dropped below freezing
And that's how the "freeze plug" name came into being

There is no down side in using expansion plugs, just costs more than metal ones, but these are way easier to install in tight places

No, I don't know the size of your core plugs

 

There are 3 freeze plugs on each side of the block. They are 1.5" in diameter. Check the passenger side, those seem to always rust faster. If you go with exact replacement free plug inserts Id suggest brass and use gasket sealant. Although Expansion rubber plugs are easier as Ron mentioned.

Get fresh coolant back in there after a real good flush.