I've obtained all 3 items that Grobnar needs and have given them to him (one a time, right after I got each one), but the quest isn't advancing. Was I supposed to give him the items all at the same time? I've looked online and in the toolset for the item codes, but I can't find them, which is odd because the items ARE in the game. Anyway, does anyone have any suggestions on what I can do, or am I screwed?

According to gamebanshee, you need to be in the basement to do the quest. You can read the details in the link.

Thanks for the help, but I did that. I gave all the items to him (in the basement) through dialogue. Each time I gave him something, he said it just needs a little more. Do I need to be at a certain part in the story for it to work?

Have a look in your globals.xml in the saved game, see if it shows you have 31_nConstructParts (3)

These are the construct related intergers (they won't be all together like this) and their is probably a couple about the glow pool vial.

I haven't tried this, but possibly just adding the ones that show you have repaired the construct and done the upgrades will work. (save a copy first)
[spoiler]
<Name>23_bFoundGolemcraft</Name>
<Value>1</Value>
</Integer>
<Integer>
<Name>__conv23_cs_golem0</Name>
<Value>1</Value>
</Integer>
<Integer>
<Name>00_bTome_Mentioned</Name>
<Value>1</Value>
</Integer>
<Integer>
<Name>00_Grob_Talk_Tome</Name>
<Value>1</Value>
</Integer>
<Integer>
<Name>31_b_golemcraft</Name>
<Value>1</Value>
</Integer>
<Integer>
<Name>31_nConstructParts</Name>
<Value>3</Value>
</Integer>
<Integer>
<Name>24_bFoundIronpiece</Name>
<Value>1</Value>
</Integer>
<Integer>
<Name>31_b_ironpiece</Name>
<Value>1</Value>
</Integer>
<Integer>
<Name>bConstructCompleted</Name>
<Value>1</Value>
</Integer>
<Integer>
<Name>00_bConstruct_Joined</Name>
<Value>1</Value>
</Integer>
<Integer>
<Name>00_bCon_Craft_Armor</Name>
<Value>1</Value>
</Integer>
<Integer>
<Name>00_bCon_Craft_Weap</Name>
<Value>1</Value>
</Integer>
<Integer>
<Name>00_bCon_Craft_Alchem</Name>
<Value>1</Value>
</Integer>
[/spoiler]

Awesome, it worked! I simply changed the value under "31_nConstructParts" to 3 and the game was tricked into thinking I had all three parts. Thanks for the help!