Hi and thanks for using 2CarPros.
First, make sure the motor oil is clean and full. Now, a heat shield can be noisy and rattle. However, I don't know for sure that is the problem. Can you record the sound and upload it for me to hear? If I hear it, I should be better able to recognize the sound.
In the interim, here is a link that discusses engine and related noises. Take a look through it to see if it helps.
https://www.2carpros.com/articles/engine-noises
Let me know.
Take care,
Joe
Saturday, March 2nd, 2019 AT 6:16 PM