W95civicEXcoupe

EJ1/D16Z6. After car was shut off, it made these noises after both times it was shut off after a drive. The noises are faint but it kinda sounds like "rumbling tank." (*this happened after I filled up my overflow reservoir before my drive.)

Thoughts?

Video: (*by the way. Hood shut after a righteous slam of just letting the hood fall down. Weird. What is up with my bumper now though) ?

https://www.youtube.com/watch?v=Rv1-UqIciJU

W95civicEXcoupe

Better video coming up. From shut-off to emergence of noise. What is going on for that to happen?

Thank you

https://youtu.be/aBgeEkOChWs


https://www.youtube.com/watch?v=aBgeEkOChWs

W95civicEXcoupe

Ok well FWIW I flushed the whole system today. CLR I used. Replaced a heater core hose that had a leak and sprayed under pressure. Bled for air. Tomorrow I flush again with water, all the CLR out.. then I replace with 50/50.

Has not yet re-occured..