2005 V6 possible head gasket issue

I have an 05 with a questionable past but a few months ago I was getting ready to leave it was chilly but not cold I noticed the white smoke and kept an eye on everything from there as i got further from home the trucks temp gauge began to rise I turned around and went home... since then she has sat being started periodically until I waited about two weeks and tried to start her only to hear the most god awful clattering so I immediately killed the ignition and it sat for about 6 weeks when a guy asked to buy it and he started the truck ( I asked him not to but there was a language barrier) it started and ran loud and ugly so I cut it off again... another friend and i discovered the "Tacoma Clatter" and I restarted the truck only to have the sound stop and the truck return to its usual running condition minutes after starting since then i have noticed a drop in coolant but the oil shows no signs of contamination.... head gasket? please any insight would be helpful...

 

You should also get a CEL or all of the warning lights on, TRAC, VCS, everything. Depending upon where the coolant is going you may not see any in the oil or see an oil level rise. Sounds like a head gasket to me but then the best thing to do is a pressure check on the coolant system, drain the oil and look for radiator fluid. The radiator fluid is going somewhere -------- .

 

It's possible you have a headgasket problem but there are multiple test methods to verify it, typically the first signs are mystery coolant loss, misfiring on cold starts, and mystery overheating.

The rattle/knock on startup after extended sitting is more than likely timing chain rattle/phaser knock until oil pressure comes up to put tension on the chains and keep the phasers in time.
It can be an early sign of timing chain wear but alot of engines will do that a bit after sitting for extended periods. If it gets to doing it every morning on a cold start then it's time to start thinking about timing component replacement.