Clunk Noise 5 Secs. After Start Up?

[jrbet83]

I have a 2010 5.3 Sierra 4x4 with 7000 miles on it. The last three starts there's been a bad grinding clunking noise coming from the right side of the engine compartment (passenger side), about 5 seconds after start up. Does it once then won't do it till the next cold start up. It hasn't done it when it's really cold like 25-35 degrees in the morning, but does it after work when it's 45-60. Oil level is good.

 

What could this be? Ever heard of a compliant like this?

[jrbet83]

It's not the starter. It has a pressure release sound to it....... So nobody as a clue?

[rick08]

I had the same thing on my 08 Sierra, a loud grinding sound, only lasted a couple of seconds but mine was at the end of a really hot summer day. It turned out to be something with the AC compresser. I took it to the Dealership and they flashed the PCM, Never heard the sound again.

DocumentID 2022356

Hope this helps,

Rick