I have a 2009 H3. This is my 3rd H3. I never had trouble with any of them. Last July I took it into the dealer for an oil change and tire rotation. Within 2 weeks I had the vibration. I took it to another dealer and they said it was 2 qts low on oil. So they changed the oil and wanted to do an oil consumption test to see if the engine was consuming more oil than it should or if I was shorted oil They had me come in every 1000 miles and it was full each time and the vibration continued and then new things started to happen. Finally I talked to a tech at the dealer who intervened after 5 months of the stupid oil check which was full everytime. The heat shield had now rattled loose which you could hear, so that was fixed and they tightened some engine mounts. I got it back and the vibration was still there. I am talking the seat, steering wheel, door etc visibly shook. So I took it in again and they said it had a collapsed engine mount they could not see until it was off. Got the Hummer back, still not fixed and it is back in there again. Thankfully I had renewed my GM warranty before it expired so this will be covered but I am fed up with the dealer having the Hummer more than I do. I do not believe it is the engine. The tech told me he had that engine in a Canyon and never had an issue. As I said I have had 3 H3's and never had one issue until now. I will let you know if they figure it out. I came on here hoping to find a solution on my own.

 

I hate jumping in on this old thread but there seems to be a lot of ppls opinions on here as to what it is. Mine also started vibrating quite a bit at idle and I just figured oh well everything still runs fine but it is annoying. so tomorrow Ill swing by my local advance auto parts and have them run a quick diagnostic on it and see if any misfires are happening or if any coil packs are bad. seems like that is the most likely thing for my situation. I have an 07 with 36,xxx on it. Id be happy to replace a coil pack and have the issue resolved. Ill post any results I get.

 

@qci....mine was/is doing the same thing. Shop said they would replace the motor mounts and if it didn't stop it, they would put the old ones back in and not charge me for the mounts. It didn't eliminate it however they said it was so much work, they left them in. Personally, I think it helped a little but not a lot. Shop owner went with me to closest town that sold Hummers and we test drove a few...surprisingly, mine had even less vibration than the new ones! So, that is where it stayed with mine....hasn't gotten any worse with time.

At Hummerx3....I find it interesting that you had your tires rotated at the same time. I would be curious to rotate the tires again to see if makes any difference. The reason I say that, is that for some reason, everytime they jack my Hummer up with their handjacks at the tire store to rotate the tires, when they put it back down, I have no vibration...but shortly it returns. I have had people confirm they see the difference, but no one can find why in an effort to make it permanent. When I read your post, I just found it interesting that you had tires done at the same time the problem started.

 

Cleaning the TB fixed mine. I now do it once a year.