I'm at about 94k and the dealership "suggested" a sparkplug change. I haven't had a chance to dive under the hood, but can this job be done with only removing the plastic cover or do I need to remove the intake manifold?
The intake plenum (upper manifold) should be removed. Some have changed plugs without doing so, but found the task more cumbersome due to space constraints. It's also a good idea to put in a new gasket when reinstalling the plenum.
On my earlier model- 2010, the intake is aluminum as compared to the black plastic ones in later years.
But I found that fine dust and small rocks have accumulated in the area of the plugs/coils and intake.
I vacuumed this area. I also used a mirror to check the inside of the spark plugs to make sure there was no liquid seepage and or particles that fell in. (which could then fall in further when the plug is removed).
I was able to change the plugs on my wife's 2007 Acadia (did it @100k & 200K). The rears are a pain, but I didn't have to remove the upper intake plenum, but I needed 3 swivels and 3 extensions to get to the plugs. Also, the coil packs are not fun to remove, but a 10mm socket and a mirror will aid.
I think it took me ~4hrs for the whole job (all 6 spark plugs) with the majority of the time on the rear 3, for the first time. The second time, I was able to finish in 2 hrs - since I knew what needed to be done.