Howdy,

Over the weekend i was busy tried to purge out air of my 95 Ranger with 4.0L. I followed instructions and all that to ensure there no air in the system, however no luck and the cost of coolant ... you know it it's EXPENSIVE!! soo I'm wondering with two hoses that hooked up to heater core pipes comes out of the firewall ... which coolant get circulated first into the core? from the water pump or the intake manifold? I'm considering of adding bleeder valve like seen here -> https://www.rxauto.com/ez-bleed/ (east bleeder 1) on bottom of that web page

let me know and Thank you

 

Welcome to the forum

It is a self purging system but you want to get most of the air out when refilling.

Just remove either heater hose from firewall or by-pass valve, whatever is the highest point.
Then refill thru radiator cap opening until coolant comes out the hose and Core(firewall)
Reconnect the hose and all the air is out.

Not that it matters at all since there is no direction of flow thru a heater core, but the coolant comes from the water pump hose, goes thru the core, and then back into the intake by thermostat housing.
You SHOULD reverse the heater hoses at the firewall every time you change coolant, this back flushes the core which will make it last longer.

Leave radiator cap off after refilling and start engine.
Coolant should NOT come out the cap opening, if it does then you have other issues.
Make sure Overflow tank has coolant in it, to COLD line at least
Let engine run for 2 or 3 minutes, and top off radiator as needed
Put cap back on and go for a drive longer than 15 minutes
Put TEMP to HOT, you can leave Fan off
Temp gauge should go up to just below 1/2 way, 190degF, 210degF is 1/2

If it goes higher than 1/2 while driving on flat ground then you have other issues NOT air in the system.

After driving shut off engine and let it cool down.
4 or 5 hours at least
Open rad cap and coolant should be at the very very top, this confirms there is no air left in the system.
If there is air then rad cap or overflow hose or tank is the most likely problem.

When coolant heats up it expands in volume
That creates the Pressure in the system, NOT the water pump
When pressure exceeds 16psi the rad cap opens and sends extra pressure and coolant to overflow tank, any "air" left in the system would be at the top of the radiator at that time, and it would go out FIRST and into the overflow tank, where it would bubble up to the top and be GONE.
After engine is shut down the coolant cools down and shrinks back to cold volume which causes pressure to go down to -1 psi, this pulls open the smaller valve in rad caps center, which SUCKS coolant back in from overflow tank.
So self purging system, air out, coolant back in


And just a heads up on the 4.0l OHV engine, if it is EVER overheated a head will crack, no do overs, it WILL crack.
Cracked head causes "air" to be pumped into the cooling system, this displaces coolant and causes overheating.
So if you have reoccurring "air' problem then you have a cracked head
Pull out all 6 spark plugs
One will be "steam cleaned", very white tip, thats the cylinder with the crack

 

Thank you for your answer within my questions ... I will take a look at spark plug and hopefully it's not steam cleaned with white tip. So far i checked oil and it's not milky. so far it hasn't overheated yet ... so just for precaution i will check spark plugs ... if it's clean as whistle then i'm darn lucky on this one with no crack head if that's the case then i have work too do on fixing it

I will get back with ya on this

 

Milky oil still happens but hardly ever any more with blown head gaskets, better gasket material prevents it
And it could never happen with cracked head, no connection to oil passages.

Hope you get the air in the system sorted out