1980 Jimmy Build - K5 owner again...

[BC98]

I have a love/hate relationship with bodywork and I had started to hate it (again) so after the tailpan was installed I took a brief break from the welder, cutoff wheel and grinder and switched to something mechanical. I pulled the LQ4 out of its temporary storage location (i.e. the engine bay) and got it mobile on a stand. At some point I had decided that I wanted to switch the engine to drive by wire so I pulled the engine harness, throttle body, intake, and ECM from a 2004 Denali out of the junkyard. The throttle body and intake were swapped onto the engine and I modified the wiring harness based on the very detailed YouTube videos from LT1swap.com. I also grabbed the pedal assembly out of an OBS with the 6.5l diesel and modified the plug to work with the 2004 TAC module. The ECM was updated to remove the VATS and CELs for the rear cats with PCM Hammer and LS Droid. I am going with Earl's Vapor Guard EFI hose and grabbed a TBI tank, sending unit and Delphi pump to get the right pressure for the fuel injection.

I had wanted to test fire the engine before I got everything set with the Jimmy for a number of reasons. 1) The engine had been disassembled/reassembled by me, 2) been sitting in my garage for over a year, 3) I had no clue if the engine would build oil pressure, 4) Didn't know if any fuel or oil leaks would be present and 5) I wanted to make sure that my modified harness would actually work. I was able to get the engine set up on a stand with a sketchy fuel system (my pump and sender dropped into a 5 gallon bucket with gas), the OBS pedal, a battery on the floor and the underhood fuse box from the donor Yukon. Definitely not OSHA approved but it worked like a charm. The engine cranked once and then fired right up. It idled great, no leaks anywhere, built good oil pressure and didn't throw a single code. Even the throttle pedal worked. Unfortunately, I was like a kid with a new toy and forgot to take any photos of the setup or video of the test fire...

 

[BC98]

Properly motivated with a running engine, I switch back to my role as a body man and tackled the install of the rear cargo floor. It took a little longer than I had wanted but was able to piece the majority of the floor back in and I'm relatively certain that it is won't leak. I'll be laying seam sealer over all joints and welds once I'm done so I'm hoping that should keep the cabin watertight once this rig is back on the road.

 

[BC98]

I spun the truck around and started tackling the front frame ahead of the firewall and front suspension. Based on everything else that I have found wrong so far I was assuming the frame would be cracked around the steering box so I wanted to address that with an ORD weld on repair kit, as well as install some of the Deuling Design frame plates and ORD steering box brace. I also cleaned the springs up, installed ORD bushings and HD shackle along with an EZ Inch up front. I was pleasantly surprised to find the frame had zero cracks so that was a nice change. While I had easy access, I also installed an ORD high clearance crossmember and Comp motor mounts.

One note: I installed the small-block version of the ORD crossmember knowing that I would likely have clearance issues with the stock LQ4 oil pan. My reasoning was that if I decide to build this truck up into a trail rig down the road, I wanted to keep it fairly low and still maintain as much uptravel as possible in the suspension. I did confirm that the truck pan interferes and ORD suggested a pan that should work with the combination.

 

[BC98]

Currently, I am back to body work. I stripped everything off the firewall and am working on rust repair along the seam between the upper cowl and firewall. It is definitely suffering from some leakage due to hardened/cracked body sealer in that area so I will address the rust, chip out the old seam sealer and apply new. There are also a couple of small holes in the windshield channel that I'll need to fix (one is actually done already).

In the meantime, I have been scouring FB Marketplace for used body panels so that I can avoid needing to patch up the existing parts. I've been able to find really good deals on a driver's door and fender and they're waiting to be swapped on when some of this other stuff is done. I would really like to finish the firewall work, set the engine in place, and get a front clip mocked up to get a little bit of motivation. It will all get blown apart again later when I do the final wiring and some brake line work but it would be really nice to see it as a "whole" vehicle for a little bit.

 

[BC98]

Wow, I didn’t realize that it’s been over three years since my last update. Since my last post in 2022(!), I was able to finish patching up all the rust in the firewall and coated the firewall in primer. Due to the pretty extensive rust in the upper firewall area, I ended up pulling the remainder of the wiring out of the body. The plus side to this was that I really got a chance to look at the whole harness, inspect it for damage, and learn a little bit more about the wiring on my rig.



As far as non-bodywork related things, I was able to get the steering column rebuilt. I put in a new turn signal switch, horn components, lower column bearing, and new key/ignition cylinder. I also got a chance to threadlock and tighten the 4 bolts from the tilt mechanism along with getting a turn signal stalk (1983 Suburban) and wiring that will let me run the cruise control through my DBW engine harness, and cleaning/painting all of the metal parts.

Other junkyard & Facebook Marketplace finds included: a good set of doors from a Suburban with power windows & locks, a (hopefully) functional 4L80E from a GMT800 series Suburban, a gauge cluster from a ’90 Suburban, front seats from a 2005 GMT pickup, and rear seats from a 2008(?) Suburban, and a few other small things.

To date, here’s the bodywork that has been completed (in addition to what has previously been shown):

• Patch work on the front of the hood (I like the added body lines stamped into the front of the ‘79/’80 hoods)
• Large rust spot and fill of trim holes on the tailgate
• Kick panels replaced (driver and passenger)
• Inner and outer rockers replaced (driver and passenger)
• Front and rear floor braces needed metal repair on the flanges that welded to the inner rockers (driver and passenger)
• Portions of the floor next to the inner rocker were replaced (driver and passenger)
• A section of the footwell for the rear passengers was replaced (driver and passenger)
• Small holes in the cross brace that the front of the cargo floor bolts to had to be patched (prior to the floors covering it back up)
• Part of a vertical support brace that runs from the cross-brace mentioned above to some of the lower stiffening structure underneath the floor plan had to be fabricated and replaced (driver and passenger)
• A support structure inside the B-pillar was repaired (driver and passenger)
• A new lower b-pillar panel was fabricated (including the lower seatbelt mount) and welded into place (driver and passenger)
• Repaired inner wheel well panels (driver and passenger)
• Repaired driver inner wheel house and replaced passenger inner wheel house (AMD)
• Reinstalled both and seam sealed joints

 

[BC98]

At this point, I THINK that I have all of the interior of the Jimmy sealed up and ready to be primed, seam sealed, and top coated. In late summer, I decided to switch gears a little and get the underside of the body cleaned, prepped, and sealed. Unfortunately, the only way to do that was to pull the body off the frame to get access to all of the areas on the underbody and the frame that still needed to be cleaned up. By some weird patch work of car dollies, jack stands, a floor jack, and an engine hoist I was able to get the frame out of the garage and the body propped up on jackstands.



While the weather was nice, I concentrated on cleaning the remaining surface rust off the frame and getting those areas treated. I primed and topcoated the whole frame with a combination of Seymour primer, MRO paint, and Rustoleum Professional flat black. The two exhaust heat shields (one on the frame and one on the body) were removed, all of the previous undercoating/mud was cleaned off and given a fresh coat of primer and high heat paint. Unfortunately, I didn't get any good pictures of that.

After the frame, I moved to the underbody of the GMC. The vehicle had factory undercoating that was a bear to remove. The biggest problem was that about half of the coating was dried up and brittle (this was actually the easiest to get off) but the other half was actually still “wet” from several engine oil leaks from the previous powerplant. Top that with a hefty amount of dirt from its previous life and it was, well, gross. And a giant, messy, PITA to clean off. But it did eventually came off and I painted the whole underside with Zero Rust, seam sealed every seam panel seam and patch that I welded in, and coated the underbody with Raptor Liner. I am really happy with the way it came out.

Fast forward to last weekend, and I had to rush to get the frame and the body back together because I needed space in the driveway to replace an alternator in my Tundra. Through another patch work of car dollies, a car jack, engine hoist, AND the Tundra, I pushed the frame back under the body and got everything bolted back up with a new set of poly bushings that I got from ORD a long time ago. And we are fully caught up to now.