Thanks for all the advice guys.. I'm not so worried about the mystery hole now

I was thinking I could pop the upper half of the timing belt cover without tearing anything out. I removed the bolts from it, but it doesn't seem to come free. It looks like it should be able to slide down and come out... Am I mistaken?

 

You first need to remove the valve cover and then 2 or 3 10-mm bolts.

 

Okay that's what I was afraid of! It's not a huge deal, but I was hoping I could quickly pop the cover, take a peek and go from there. I might as well replace the gasket while I have the VC off. Anything special there or just clean the surfaces and slap down the new gasket, torquing everything per the manual?

 

The valve cover gasket can usually be reused. You just need to lift the one end of the valve cover enough to unhook it from the timing belt cover. Take the nuts or bolts off completely but you can just pull the spark plug wires up to disengage them from the plugs and leave them in the holes.