Knock sound at idle ~1500

[bd1308]

Hey folks! Amazing group of people here...Just have a little issue that I need to determine its severity ---

I have a knock that occurs when engine is near idle to around 1500RPM. I thought it was rod knock bit its not at the front of the car and seems to go away and come back. When cold, it sounds a bit like a helicopter (chop, chop, chop). All of the descriptive words I use here make it sound alot worse than it is, so imagine that each sound is muffled. I've just never heard anything like this before.

I've heard rod knock, and diesel rod knocking seems to sound twice as loud. Its not driveline-related, it does this in P and N and when under load and not.

I'm leaning toward something vibration related (I need bushings in my shifter and can feel these knocks in the shifter when they happen)

Just to re-iterate, they'll go away and come back in some kind of cycles....I'm thinking its motor/transmission mounts, but the engine doesn't really shake and the motor mounts seem good

EDIT: I found one thread that died without an answer talking about a helicopter sound, and thats the sound its making.