Rad Making Gushing Noise

So everytime i start my truck for the past couple days, i hear all this gushing, kinda like water traveling throught the Rad system...

never noticed it b4 so i took a look under the hood

poped the Rad cap and noticed that some was missing so i was gona top it off....

should i just drain out the whole thing then just top it off with some fresh coolant and to the "burp" process....

or is it better to drain, then flush with water, then fill back up with coolant...

been reading some threads about this, some ppl say when they used the Rad cleaner that there water pump went out bcuz they think that the cleaner cleaned the water pump and made the bearing dry and made it stop working or sumthing like that, i dunno....

so is this water gushing noise sumthin bad, or should i just drain and fill and forget the water/cleaner flush..........


im at 55K, i hav an 06, V6........i got it used so im not sure if they did it, i didnt have a copy of any Rad maintence so im guessing that they didnt.


help,

 

so i did a lil more research and i think its from a low coolant level.....also some other ppl at other forums said it was their power stearing, but when i looked under my hood yesterday all my levels were good except for a lil missing coolant.......


i think im just gonna blast my heater on my way home, pick up some coolant, get home, wait for it to cool, than drain, then fill back up, then top off as needed, incase there are air bubbles and it burps it out, then i need to add more coolant as the air bubbles come out and create more room in the Rad for more coolant.

anyone see anything wrong with im gona do tonight?..........kinda werid but i feel like im talking to my self, maybe cuz i am lol.

i guess im just thinking out loud