I did the cleaning the LIM, coolant passage block, and the porting out of the LIM passage at the endcap. I went and ahead did this today while I was in there for: New Valve cover gaskets, NEW LIM Gaskets with metal gaskets (not faulty plastic anymore, and it came with the tube of black RTV sealant), new dorman UIM with reinforced/aluminum chimney for the Exhaust Gas Recirculation port, new PVC valve (came with the dorman UIM), new fuel injector O-Rings (6 came with the dorman UIM, and 6 came with the LIM Gaskets), new thermostat gaskets (came with the LIM Gaskets), new map sensor seal came with the LIM Gaskets), new water pimp, new heater hose fittings that connect into the LIM and block, thread sealant for all LIM bolts and water pump long bolts, and cleaning/detailing everything including all bolts (one LIM bolt was so corroded I had to buy a new one).
Here's my ADDITIONAL NOTES for the mods:
Cleaning the LIM:
It's been proven that engines run cooler and better when clean. When an engine runs cooler, it makes more power, it doesn't wear down, and has more tolerance to the abuse you give it. Really this goes for everything in life, something clean runs/lasts/looks better than something dirty.
Coolant passage block:
Use a 7/16" drill bit to make the hole large enough to start the tap. Next, take your time with the tap, that's the key. I thought I needed a special holder for the tap, but no, just the tap. I went to an autoparts store, asked for the 1/4" NPT tap and two 1/4" NPT brass plugs, no problem... OK, I confess it was more a bolt store, than an autoparts store, but similar.
Porting out of the LIM passage at the endcap:
I didn't need any special GM Gasket. I simply purchased a roll of Felpro gasket Material for $3 (aka karropak 3045, O'Reilly carries it), and tapped out the gasket I needed with a ball peen hammer. Now I have plenty of gasket material for anything else I may need in the future... and it was cheaper/closer than driving to the dealer.
Next, I used a [right-angle] grinder and a cutting wheel and very careful grinded out the interfering area.
slap it back together, and voila! Well, OK, it was easy for me, since I happen to have these things lying around.
