Originally Posted by jruthven

Awesome information j_martin. I removed the old thermostat early this morning and swapped in a new one. After taking the truck for a little ride, the lower radiator hose is warm to the touch, whereas the upper is not. Is this normal? The temp gauge still hovers to the right of center... But I am thinking I need a better gauge than the terrible factory one. What temps should I expect to see? I am in the process of removing the plug above the t-stat housing in order to burp the system - I didn't realize that this had to be done. It's in there pretty tight... Going to put some penetrating lubricant on it and work at loosening it up. Thanks so much for the help

Originally Posted by j_martin

It's a tapered pipe plug. You need a good quality Allen wrench and a cheater. Either the plug will come out or the wrench will break. Usually the plug comes out. Pipe threads are both tapered and 100% fit, so pennetrants usually don't help much. When you re-install it, lube the plug and the hole (very little) with a good quality teflon pipe thread sealer.

Don't even try it with a dime store wrench. You'll just wreck the wrench and the hole in the plug, leaving you with the chore of drilling it out.

Originally Posted by jruthven

Update: I pulled the plug out, installed the new Cummins thermostat, and filled her up with fresh coolant. After that, no issues whatsoever. Thanks guys!

Originally Posted by j_martin

Ain't it amazing how good things go when you do it right?