91CavGT, good work. We Colorado owners will have to pool our knowledge. I just bought the truck this month and I'm just getting started on FE mods. Since mine's a crew cab, 3.5 and auto we should have some interesting comparisons. I have a ScanGauge II, so I'm monitoring what goes on. More later.
Oddly enough, after blocking off ~75% of the grille on my Jeep Cherokee, I noticed that the coolant temps came down as well!! It's difficult to verify with hard numbers, as 89 is before the time of the Scangauge....but it seemed very odd to me.
However....the temperature of the engine bay seems to have risen.....I've noticed that after a long drive, I need to pop the hood to keep the coolant temps from climbing
91CavGT, what's involved in pulling the Colorado grille. I thought I'd piggyback on your knowledge. My Colly is my only vehicle, so I need to work quickly on projects.
I started to do a grille block with black coroplast like I did on my xB (traded in on truck), but decided your back side solution would look better.
You actually don't need any tools to remove it!!
First off, unplug your DRLs on each side at the top and get the wire harness clear of the little built in clips that hold it (not really clips, just spots in the grill that the harness fits into).
After that, there are 4 little clips on top of the grill. They are little black horizontal plastic things. Push them down and you will see that they can slide back slightly into the grill. Just don't push them too far.
Next start on one side of the grill. There are 2 larger silver clips around the lights on each side, and 3 of the clips in the center of the grill towards the bottom. On one side, grab the grill and with a slight jerk, pull it straight out. The clips will loose their hold and the grill will start to come off. Do the same for the center of the grill (you can usually reach your arm down there to help pull them off). Once you pull them off on the passenger side then the whole thing will come off. If you don't want to pull the grill then you can get a long flat head screw driver and use it to pry the clips loose.