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Q: Engine knock

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I have an engine knock and I have guesses on what it is but not sure. Prior to this knock my engine battery and died then on my next start up it was good until I came to a stop light then my car started rattling and reving at low 500 rpm and from my recelection it stalled. Now I have this loud rattle when I start the car I do have a video on this knock for better understanding. It's at https://youtu.be/ljvSWo3eKa8 . I either think alternator gone out but my buddy's say maybe it's a cracked intake manifold, spark plugs bad (but wouldn't that make a popping noise misfire), rod knock, rod bearing spun, or the engine is no longer good

Thank you for your time !

My car has 180000 miles.
My car has an automatic transmission.

Based on the sound heard in your video, I believe you have damaged some of the valve train parts. If this happened during the engine dying, it is very possible that something has broken on the inside of the engine. I would recommend enlisting the assistance of a qualified technician to determine if the engine can be rebuilt or if it requires replacement. If the engine requires an overhaul or replacement, I would strongly recommend having this done professionally to make sure the job is done properly and will last many miles down the road.

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