Vibrations maybe bad motor mounts

[sctrl]

Hey everyone. Got a 08 Denali few weeks ago. Love it so far!

I've been noticing vibrations while sitting on the red light. They are coming through the brake pedal I can feel them in my foot, almost like rough idle, but RPMs are solid. Also going past 50s I can see vibrations in the dash. Like my phone is attached to the mount and I can see the screen vibrates just so subtle. Also shifting from between D and R also feels like something is moving under the hood.

I thought it might be the motor mounts. So I recorded a video of the engine going through start-up, a bit of throttle, and shift from P to D to R. What do you guys think? is that enough engine movement to point to bad motor mount(s)?

 

[OR VietVet]

I personally do not see enough movement. Others with that year will chime in with better knowledge. Did you get maintenance/repair paperwork with the rig? You can have a vibe at idle and still have a smooth rpm gauge. Codes?

 

[Fless]

Are you powerbraking it when you punch it? In gear?

 

[avalonandl]

Check your plugs and wires.

 

[wsteele]

It was a little unclear what was going on in the video. When you revved it, was it in drive with you standing on the brake? Or was it out of gear when you revved it and only changed gears while idling?

 

[sctrl]

It was a little unclear what was going on in the video. When you revved it, was it in drive with you standing on the brake? Or was it out of gear when you revved it and only changed gears while idling?

I revved it in P, and then changed gears while idling.
There are no codes.

 

[gooffeyguy]

Snap a pic of the drivers side mount. The previous owner may have replaced the mounts with H3 mounts, which on the 6.2l will give a very slight vibration at idle

 

[OR VietVet]

I revved it in P, and then changed gears while idling.
There are no codes.

That doesn't tell you anything. You have to be in either reverse or drive and foot firmly on the brake pedal and the park brake on and snap throttle it in either gear and then the engine will torque and try to lift from the mount. Don't hold the throttle down, just do a snap throttle. If the mounts don't allow any more movement than what was already seen, then you have no mount problems other than what @gooffeyguy said.

 

[wsteele]

I revved it in P, and then changed gears while idling.
There are no codes.

What @PNW VietVet said. That is why I asked.

 

[sctrl]

I gotta do this test you guys suggested with revving in gear.
Meanwhile here are pics of motor mounts.

Passenger side mount


Driver side mount