weird sound when starting

[Ganja Man]

ok i got this car about 2 weeks ago from a dealer. has a brand new engine with only 25k miles on it. the rest of the car has 97k on it. everything is stock. it started up fine this morning but after driving around for a while and i started it again i heard a weird metal clank noise for about 3 seconds then it went away so i turned car off and started it again. it made the same noise. after about 3 sec it goes away and i dont hear it again until i start the car. not sure what this could be. any input appreciated.

 

[Sotarts]

Check if the heat shield around the upper end (right before flex) of down pipe is loose.

 

[Ganja Man]

hmmm well the other day i was going out of town. i get about 20 miles out then my car starts over heating. found out had to get thermostat replaced. now it doesnt make that noise anymore. could a thermostat make that kind of noise i explained?

 

[theTuner]

lifter tick? i hvae it too