a noise when engine started?

2014 MERCEDES BENZ B200
190,000 MILES • 2.0L • 4 CYL • 2WD • AUTOMATIC
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PHILIP GAO
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Be in Peace Gentlemen.

The actual model is B250 with a 7 speed Dual Clutch Transmission.
when start engine, intermittent come a special noise, record the follow video, the Gear is still at Park
1st video outside
2nd inside to see the engine speed from 1100 to 770 around 3 minutes.
https://www.youtube.com/watch?v=LkPJI1pUFeY

https://www.youtube.com/watch?v=H33PgF0jvTg

Question:
Where is the noise possibly coming from besides the engine noise when the gears is still in park position?

someone said the transmission should be replaced, but when I run it on the road, the transmission switch normal, the noise beside the engine sound intermittent come no matter the gears switch

Just a DIY customer, thank you any idea!
Sep 2, 2024 at 9:34 PM
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STRAILER
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Thanks for the videos, they help. I don't think this is the transmission especially when it is working okay. To me it sounds like you have a primary catalytic converter that has fallen apart internally. Please check out the images below to show you how to remove it for inspection. Check out the images (below). Please upload pictures or videos in your response of any problems so we can see what to help you with.
Sep 3, 2024 at 9:00 AM