Well, the RV from Heck finally broke its jinx. We have just returned from a successful trip from home to Fayetteville, NC and back. Fifth attempt to do so. First failed two hours short with a dead alternator. Second and third failed with some wonky transmission wiring. Fourth failed because of a dying starter. Fifth time was a charm. I’d found and reserved a campground near Fayetteville, had a great time with the kids, grandkids, and a nephew of my wife, in from SoCal doing training nearby.
However, the title of this post leads to a different issue. Naturally. Over the last few months I’ve rigged the Zombie Emergency Response Truck (ZERT) as a “toad”. In RV-parlance, that’s a tow-ed vehicle, or in nautical terms, a dingy. Got a good deal on a strong tow bar, made safety chains, magnetic lights and wiring, and modified the front bumper for the tow bar mounts. The trick with flat-towing a vehicle is to keep the transmission from spinning while the driveshafts are still connected. A 4×4 with a real transfer case can select Neutral on the case, and put the transmission in Park, and be happily towed. There’s some caveats, but not part of this discussion.
Anyway, the Zombie Truck happily rolled along behind the RV all the way to Fayetteville. Unhooked and used the truck several times, but noticed a rumbling noise each time. Planned to look into the problem when we got home, as I am also getting ready to install new springs and shocks (see prior breakage for reason). Well, about two hours into the drive home, I’m looking in the rear view mirror and notice smoke billowing from the ZERT. Quickly pull over and assess. Hmmm. Rear drive shaft front yoke is demolished. Some ATF from the transfer case (correct for an NP208). Transfer case is HOT to the touch. Being on the side of a busy Interstate, didn’t see a need to troubleshoot or inspect, just get back on the road. So, I unbolted the rear driveshaft’s rear yoke and used heavy zip-ties to suspend it under the truck from the frame. Didn’t want to pull it completely, GM used a slip yoke in the front and removing the drive shaft would cause leakage of ATF. 20 minutes after noticing smoke, headed back down the road. In reality, I could have safely pulled the rear drive shaft entirely and not worried about ATF loss.
Got home, pulled off the center console rear panel (upholstered plywood, 6 screws), and looked down at the transfer case. Or more exactly, what remained of the transfer case:
Ummm. Front of the ZERT is to the right, the rear driveshaft is out of the picture to the left. See the big piece of aluminum that’s vertically oriented in this photo? That runs crosswise in the ZERT, has the transfer case chain inside, you can see a little of it. That dark-colored set of gears, shifters, etc. in the upper right of this photo? That used to be contained in the forward half of the transfer case. About 1/4 of the complete transfer case is missing, most of it being the front half. Along with all of the fluid from the case. Big Bada Boom somewhere after we left for home.
Couple of theories, nothing for certain other than that this transfer case is now an expensive piece of scrap metal.
My first guess is that the U-joint on the slip yoke on the rear drive shaft got loose, worked the rear seal out, causing loss of ATF from the transfer case. No lube, no cooling. Kaboom. My second guess is a little more complicated: The transfer case in this vehicle is rotated about 40 degrees out of normal position for better ground clearance. Custom adapter between the transmission and the case. The pump in the case may not have been able to pick up fluid if it was too low. Same result: no cooling, kaboom, though I wasn’t having any problems when driving the vehicle. Third possibility is that the boot covering the transfer case shifter pushed the lever into an partially-engaged position, causing wear and heat in the gears. The transmission was in park, so I’m praying that nothing happened to that. I’ve already replaced the transmission because of a snapped input shaft…
Either way, the case is getting dropped out tomorrow afternoon, won’t take much time. No oil to drain, and I’m not going to be gentle getting it the 24 inches from truck to ground. And I’m planning, after all is said, done, replaced, will disconnect the drive shafts before towing. It only takes a few minutes, there’s no need to jack up the vehicle either.
All in all though, a good trip, and we weren’t stranded anywhere…