I just bought a 1989 cherokee with a closed cooling system. I have always had newer cherokees and I'm not familiar with the closed cooling system but noticed that the overflow tank is near empty when it's cooled can I just add fluid? Without having to burp any air out? And if so with the engine running or off!

 

Add coolant to the overflow bottle and run it until the thermostat opens, while its running air bubbles should bubble out through the overflow bottle. Shut it off, as the engine cools atmospheric pressure will draw coolant back into the engine, keep doing this until the upper and lower hoses are tight when the engine is warm. Be careful not to overheat it while your idling it, my friend did that and cracked his head

 

If it's "near empty when cold", add coolant to no more than 1/2 of the bottle when cold. Re-check frequently when cold.