This doesn't qualify to "what'd I do to the GM truck today", as all I did was drive it...
Took the Sierra on a long trip yesterday to get a truck bed tool box (the kind that mount in the front of the bed, side to side). Guy was selling it for $100 (same one new goes for $430 now), and it takes up less room in the bed than the wheeled storage trunk I carry tools and stuff in, so I figured I'd jump on it.
Trip was uneventful until I stopped for gas on the way home. Left the engine running, as the battery sounded weak, even though it was damn near fully charged, thanks to the hours on the highway.
As I'm finishing the fill, I'm thinking... "damn, the valvetrain sounds noisy... why is that?"
After I put the fuel cap on and get back in the truck, I found the windshield had totally fogged up from the inside. "That's weird... "
Turned on the defroster and sat for a minute until I could halfway see, so I could move the truck out of the fuel bay. Then the DIC dings and tells me "Coolant Temp Overheat" (or something like that). WTF? Then I look at the gauge... it was exactly one notch from being pegged at 260F. NOOOOOO....
Get the truck to a legit parking spot, in case I was going to be there awhile, and shut down the engine. Looked at the coolant tank, and it was full. It was then that I figured out... I lost the e-fans. They'd been working like a champ for six months or more, up to that point.
Grabbed an energy bar and a drink at the inconvenience store, and waited about 45min... and the gauge was below the halfway mark. I saw the serpentine was in place, so if I could keep moving, the temp would stay at it's rock solid 192F, just as it had the whole day.
Made it home without further issue (but very stressed, of course) and parked it until daylight.
Checked the two fuses today; they were fine. Started up the vehicle cold, and turned on the A/C, which should trigger both fans. Neither ran. Connections are good and tight, so it's time to take the Envoy out of the garage, pull the Sierra in, and start digging in depth, along with the scanner, so I can command the fans on, etc. Since this is a retrofit kit, I doubt I'm going to see any codes, even though I take advantage of the two PCM leads to turn the fans on / off. No CEL light on, either.
A shame, because I was really enjoying the scenic drive through WI, and how well the truck was running / performing. Oh well... at least I didn't blow the head gaskets (hopefully). Looks like I'd have to get past 260F (?) to warp the heads, but I won't know for sure unless I remove them.
I'd been wanting to replace the bearings in the bottom end, and figured I'd do that along with re-ringing the engine, etc. I may get to start that project earlier than I'd planned.
I did save the old mechanical fan / clutch, along with the plastic shrouds, so I can rip out the e-fans and go back to the old school setup, if I need to. I *know* that fan will run, if the water pump is turning. Sigh. And I had been giving thought to someday going with an electric WP, to free up a few more ponies. Doubt I'll ever do that, now.