Clunck on start up

[agency12]

I have a 2018 sierra 4X4 with 9300 miles on it. At times, when I start the engine, I feel a cluck like something in the transmission is engaging when it is in park. Has anyone else had this happen? It happens periodically and not all of the time so I have a hard time reproducing this when I take it in.

[1SLOW1500]

If it does in OnStar up.and not in. Gear this is odd tou.need it in the air to look over everything. Hate to here it is a tc.

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[Jacoby]

1 hour ago, 1SLOW1500 said:

If it does in OnStar up.and not in. Gear this is odd tou.need it in the air to look over everything. Hate to here it is a tc.

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Huh?  Stop typing while driving bro. You’re gonna kill someone

[Alec DiAstra]

Does this happen when starting on a hill? or all the time? Does this happen after having used 4wd? 

[agency12]

Alec, happens when starting up on level ground at random times in 2wd. Have not had the chance to use the 4wd so we can take that out of the equation.

[1SLOW1500]

Sounds like the tc to me. Engine spins and the tc spins and the truck isn't in gear so we know it isn't driveshaft and rear end. Has to be in trans or bad engine but engine would have codes or a larger issue I would assume.


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[gm125800]

Glad to see i am not the only one who has felt this. My driveway has about a 5% incline. I apply the parking brake before shifting it into the Park position as to not put any stress on the trans. This doesn't happen on every startup though.