servantsalesmen

Does the truck vibrate when it's not moving? If so, it's likely somewhere in the engine, flexplate, or torque converter.

Are all of these issues happening with chevy's or are some GMC's doing it too? If it's just chevy's then that could help narrow it down.

Measure twice buy once!

Here's mine! 2004 GMC sierra 2500HD. It's a 6.0 long bed extended cab. It has 88,000 miles and is currently broken down. Can't wait to get it up and running again though!

That's frustrating man. Sorry to hear that. Best of luck with this one. Please let us know if you find it

GM uses a crappy stamped steel plate for their flexplates and they can break. It's not super common but also not super rare. Typically a cracked plate is loudest when the engine is running unloaded meaning in park or neutral. When you shift into gear or start to accelerate you put a load on the plate and that force is enough to push it together enough to keep it quiet but the minute you coast and let rpm drop the noise comes back. If it is a flexplate, fix it! Don't let it go. Yes it is possible to put several thousand miles on a broken one but it's a disaster waiting to happen. If it totally let's go and grenades itself, there is a big metal disc heading right into the cab and it will slice through the truck like butter.

Flexplate. That's what I'm calling. Start your truck up and then get out of it and crawl underneath it and try to find the source of the sound. If it seems to come right from the bell housing on the tranny, you probably have a bad flexplate. Mine cracked in like 8 places and sounded terrible.

No its not! Go check out the k2xx suburban yukon forum on here and there is a big long thread on it. But I really hope that it's not happening with the HD trucks too. Lots of these trucks go for north of 60k and that's a lot for a vehicle with separating roof panels. I know what it's like to buy an expensive truck that goes south fast.

Maybe the roof is separating on the cross members like several of the new Yukons...

I feel that pain brother. My truck had the flexplate crack at 80,000 miles. Dealer wanted a grand to fix it. Now I have a truck in my driveway on stands with no transmission, transfer case or drive shafts.

Could the fuel filter be clogged? I might be way off and too basic but if I'm right, it's a cheap and not too bothersome fix

If it was bell housing, you'd know it right away lol! Exhaust manifold bolt wouldn't surprise me.

To me, it sounds like a cracked flexplate. I say that because I had a similar sound coming from my 6.0 and that's what it was. In the video, it seemed to be louder when you were down low. Crawl under there when it's running and listen right around the bell housing on the tranny and if it's real loud and a very sharp, metalic sound, it's a flexplate. Also, if the sound goes away or quiets when put into gear, that could be another indicator because as you apply load to the plate, the force is enough to push the Crack back together, making it quiet again.

I wouldn't trust it.... how long has it gone on? You say it comes and goes with rpm but how about with gear changes? For example, can you hear it more distinctly when it's in park versus drive or reverse. Also, try to locate the sounds origin as best as possible. Top end, bottom, back or front.