I have a 4x4 v6 4.0 automatic 99 ford ranger and my heater core valve exploded and so I replaced that and on my way home my battery light was coming on and off like every 5 seconds and I just replaced the battery. Also my truck runs super hot and I put coolant in and it seems to be gone every month There’s no sign of a leak under the car so I replaced the coolant sensor but I think I put the sensor where the sender should be does that have anything to do with my truck not running right

 

Welcome to the forum

No, neither temp sensor or temp sender can effect operating temp of the engine, they just report temp to computer and dash gauge

You have a 4.0l OHV engine in a 1999 Ranger(1990-2000), if this engine ever overheats it will cause a head to crack between the valve seats, weak point in these heads

So the bypass valve for the heater broke and you lost coolant, did the engine temp ever get above 3/4 on the dash temp gauge?

If so then you need to check for a cracked head, same symptoms as a blown head gasket, this will cause coolant to disappear and continued over heating


For the test you will need a latex glove and rubber band, OR a balloon, OR, a Condom, yes condom, lol
Also vacuum cap, OR gum, OR putty

Cold engine
Remove radiator cap, coolant should be down at least 2" below cap opening, more is fine, drain some coolant if needed to get the 2" of air at the top or the radiator
Remove overflow hose from rad cap opening, plug that opening in rad cap with vacuum cap, or gum or putty

Disconnect Coil Packs 4 wire connector, you want a No Start

Put Latex glove over rad cap opening and seal it to rad with rubber band, OR use a balloon or a condom instead of the Glove

Cooling system is now air tight

Crank engine and watch the glove
If glove bounces/inflates then you have a cylinder leak
If glove just lays there then you don't

If glove bounces then start removing 1 spark plug at a time, and crank engine again, repeat until glove stops bouncing
Put last spark plug removed back in, hand tight is fine, and crank engine to confirm glove bounces again

It is possible to have 2 cylinders leaking, so if you remove a spark plug and glove bounces LESS but still bounces then remember that cylinder, and continue on removing spark plugs until glove stops bouncing.

You want to see if one 1 head has the crack or both heads do

And no, there is almost never "coolant in the oil" when you blow a head gasket these days, it can happen but not as common as it was in the old days, a cracked head can never put coolant in the oil


A cylinder has 150psi air pressure inside when cranking the engine, so if a head is cracked or head gasket is blown then some of that air pressure will be pushed into the cooling system
That causes the Glove to bounce, removing the spark plug prevents that 150psi air pressure from building up so glove stops bouncing

When engine is running the cylinders have 1,000psi pressure inside when cylinder fires, this pushes "air/exhaust" into the cooling system, which pushes coolant out of radiator to overflow tank
And on the intake stroke of that cylinder the leak point SUCKS in coolant and burns it, so exhaust may have a Sweet smell of burning coolant and a white color
As head's coolant passages fill up with "air/exhaust" then engine starts to overheat from lack of coolant flow


Do the test FIRST get that off the table or find out if it is the problem, before wasting time and money on non-fixes

There are Block/head sealers that work temporarily until head(s) can be replaced, Rislone Head Gasket Fix is something I have used over the years and have no complaints
I stress, regardless of the claims, any of these products are TEMPORARY, and no there is no "time" on how long they last, a week or a few months