u/420steamfitter

Okay, so I shut my truck off yesterday and realized that we unlocked a new noise!

2013 GMC Sierra 3500HD (LML)

Yesterday I also realized that I have a small diesel leak if I leave the key on RUN for an extended period of time. If the truck is running, there is no leak. No big deal. However, this noise is stressing me out. It sounds like someone is in there with a little impact gun! Nobody can seem to shoot me a straight answer on this one. Hopefully one of you can help me.

Note: If I were to go to the truck right now, turn the key to RUN and then turn it back off, it'll make the noise again. I can also just barely hear it steadily while the engine is running.