I need some help reinstalling a head on a d16y5, I changed the head from one to another but head bolt #8 won't fully seat, it will get almost tight then get loose again. Does this specific bolt need to be longer than the rest? The other hear bolts all seat fine. Please help, I have to finish this by tomorrow so my parents can go to boise, its their only car.

 

it is possible that the #8 bolt threads female side is stripped and may need a heli coil insert. or there is fluid in the bolt hole causing a hydro lock to prevent the bolt to sit tight.

 

I'll check right now

 

I went back outside and my dad already had the head on and valve cover on, now its pouring oil. I'm almost certain he didn't put the head gasket on correctly and now its almost dark outside and its been raining all day which is just fantastic. I'll more than likely end up taking them to boise tomorrow in my GS-T, but may need some help tomorrow or the next day. I'll provide pictures when I do, ill keep you updated

 

Sorry for the misfortune. Rain and no valve gasket is a formula for a headache.
Hope you can fix it. The threads in the engine block sound like they are stripped.
Classic tighten almost then loose again. Stripped. There is the proper way to fix it.
Using heli-coils. Or just drilling a slightly larger hole and tapping threads into it.
Then using a larger bolt to screw in and hold down the valve cover.
The mostly forget about fixing it right and get it running fix is to put Teflon tape around it.
Enough so that it will grab the threads passed the stripped part.
But not too much that it will stop too soon. It is temporary until it can be fixed right.