Was doing the cylinder bank closest to the front today, taking on the job of doing 6 new coils & plugs due to a misfire in cylinder 4 from faulty coil (doing the easy side. I ran into 2 issues that aren't super good it seems.

First one is the plug for cylinder 2 just wouldn't come out, I didn't try anything to crazy besides some hard pulls but it was way tighter then it should have been. Did some reading online and found out that this can be caused by ether carbon build up, steel plugs doing into an aluminum head, or just from the heat causing it to expand and contract. I sprayed some penetrating stuff that's used in situations like this and am leaving it over night since I ran out of day light and I feel it would only help more anyway. If there is anything I'm missing here or a method I should try please share them with me.

The other one I feel is a bit more confusing and don't know what to think of this really. so on the spark plug tube for cylinder 6 there is an opening leading somewhere else that for me was open threads to where what seems a bolt of sorts went. Checked in the same spot but for cylinder 2 and something that looked to be a plug was in the basically same spot but in a different plug tube. I'll attach some photos to help.


This is the cylinder 6 spark plug tube and you can see the threads, which seem to be clean. Seems whatever may have been there wasn't not there for a super long time. This is kinda scary for me since I just don't know what that might be. (excuse the dirt and stuff please still have to clean the valve cover off better.


This is in cylinders 2 spark plug tube, this appears to have a plug present in that same area. Not sure though.



Any help would be very helpful, thanks for reading.

 

2nd pic looks like a freeze plug, from the picture

 

The spark plugs are most likely the original ones installed at the factory. After the engine has cold-soaked, you should be able to remove them by slowly applying torque until they break free. Go slowly so the threads in the head are not damaged.

When you install the new spark plugs, apply some anti-seize compound to the threads suitable for aluminium.

The 'plug' you reference in the photo is to cover machining of the cooling passages. The plugs also serve as freeze plugs to save the cylinder head from damage should the coolant freeze and expand. The plugs have nothing to do with the spark plugs.

 

My major concern is the picture showing the open threads, the picture showing that plug was meant as reference to maybe help find out if those open threads need that plug

 

That sure does look like a missing bolt, see if you can find some diagrams of your engine.