Knocking after 5.3 crate swap out?

2011 CHEVROLET AVALANCHE
5.3L • AUTOMATIC
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MAGNOLIA BODYWORX
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  • 1 POST
Swapped out 5.3 crate motor , have a hard knock specially when driving . Got under checked all mounts , bolts to flywheel. Heard engine with stethoscope sounds smooth. Noise sounds like from above trans area.
Oct 22, 2026 at 2:41 PM
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STRAILER
  • ✓Experienced Mechanic
  • 55,694 POSTS
Can you please upload a video of them noise so we can hear it? Does it sound like a little tapping from the top of the engine or is the noise coming from the engine down low? Some times the torque converter will slip out 1 step and when you install the engine it can damage the front pump of the transmission, here is a video to show you.

https://www.youtube.com/watch?v=ZC7xHVMKLRw
Oct 25, 2026 at 8:01 AM
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