Hello. I have this small metallic rattling noise that is 100% consistent every time the car drives off and hits 3~5 mph. The rattle is only for 2~3 secs but very consistent. Don't misunderstand. During normal stop & go traffic. No sounds. But every time the engine is shut off and cools for about 30 minutes. I drive off and what do you know "Rattling noise"....
Does anyone have an idea or share my problem?

 

1. Could it be simple preignition? What octane fuel do you use? Preignition makes the sound you describe (bolts rattling in a coffee can sound). Even though theres a knock sensor maybe its malfunctioning...try a tank of premium and then listen for the noise.

2. Something loose in the engine compartment. Maybe a bolt or nut or screw. Does it make it when you are idling or only when driving? Maybe a loose pulley bolt or something. Hard to tell from a post but those are the only ideas i can think of

 

I assume its an Automatic. In that case it could be a loose Flexplate, which is the what the torque converter is bolted to (front of transmission) The car is assembled here and i wont be surprised if someone left the bolts slack. I have a 02 Camry 4 cyl and have found lots of bolts left slack.In fact the drivers window fell down into the door at 20000 miles..all the bolts fell out. The park brake bolts were slack and caused the hand brake to wobble around. The passenger seat bolts were able to be turned by hand.The first year of the new Camrys (02)had some quality control issues.I do hope they fixed them.(Made in America).Also you can check the exhaust heat shield..they somtimes rattle.