6.2L gen1; Name this noise please?

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slade8

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Hello, please help me identify this fast thumping/knocking sound. The truck is warmed up and in park. The sound is not always there and does not go away if you rev the motor. It sounds like plastic thumping or vacuum related to me but it is concerning since I am just learning about my 2014 94k miles truck. Scanned for codes and got none. Truck runs good.
Thank you
 

rschap1

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Anything going on with the serpentine accessories/drive?
Might try running for a few seconds without belt to see if noise still there or not...
About my only guess from the video.
 
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slade8

slade8

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Thanks for looking. Sorry the video isn't the best but I was just focused on picking up the sound. It sounds like it's coming from the rear drivers side of the motor more than the passenger side. I looked in the belt area and hear a high pitched squeal that may be a pully but not related to this imo. If it's a rocker arm I don't understand why it's intermittent. I might try what you mentioned if I don't get answer on here or locally soon. Here's a longer video.
Thank you
 

Marlboroman

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Purge valve selonoid. Feel it for a pulse. Pretty common and sounds like that. It on the throttle manifold drivers side.
 
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slade8

slade8

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The first week I owned the truck it coded for the purge valve and I replaced it with an autozone $25 one. I will see if its thumping later today. That sounds like a possibility for sure. Thanks
 

rschap1

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I'll have to keep the purge valve in mind for myself if I the need arises...
I was going to mention that I had an exhaust leak a long time ago that I was sure was valve train.
Studs were ate away, manifold had cracks, and broken section of manifold would "slap" the head.
In case it doesn't turn out to be purge valve.
good luck.
 
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slade8

slade8

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work sucked and I never had time to fire it back up but will later this afternoon. I really hope it's that simple.
 
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