Not the Adventure Bus this time, just another boring tow rig.

[Joe_the_ice_man]

Well, still no snow here so imma try and drag home the chassis donor for my dumbest project yet.

Yes, it's a shortbus. Yes, I picked it up with a motorcycle after buying it sight unseen at an online auction. Yes, I'm retarded enough that its fitting that it's a short bus.

Deal is, I bought it to use as a storage locker, but I figured it's a waste of a clean VIN to not make a driver. Plan is a motorhome/tow rig. It is a C60, but the drivetrain isn't up to that task, given it's running a 350 on propane with a 5 speed manual...fortunately/unfortunately I have acquired a 6500 Topkick with a 3126 and a 6 speed manual as a drivetrain donor. I just need to drag it home and figure out why it doesnt run...

Plan is a full frame swap providing:
1. The frames are the same-ish, both being GM/Chev 6500s, they should be close enough I hope.
2. I can figure out how the hell to lift the bus body and roll the chassis out from underneath...

Wheel base on the topkick is several feet longer, but I think that should make space behind the bus body for a flat deck with a fifth wheel/gooseneck hitch for tow rig duties.

Yes, I know I'm retarded. Yes, I know I probably bit off more than I can chew. Yes, I realize this may never happen.

[Scott Cee AKA 2drx4]

Sounds like a terrible idea. I eagerly await updates.

[Joe_the_ice_man]

Well after a bit of fighting I got the Topkick home, I *almost* want to do two separate builds (just turn this into a tow rig), cause I doubt Imma get my hands on another diesel Topkick without paying a small fortune.

Diff was frozen so the back wheels wouldn't turn, had to fight out axle shafts, so that was fun.

[Joe_the_ice_man]

Well, the kitty Cat lives. Was a warm day, I figured I'd give it another shot.

Ran the block heater plus 2 oil pan heaters for about 3 hours to get some heat in there, and fed it brake clean directly into the intake, bypassing the turbo and intercooler. (On the advice of the old timer that helped me drag it home, apparently he's seen guys bend rods using ether to start these things.)

After a couple tries it actually decided to run and sounds healthy enough, which is encouraging. Really didn't want to rebuild a fuel system for 10k (just Cat things).

Tach doesn't work, but that should be something easy. Air compressor probably needs love, cause the tank was full of oil. Hydroboost pump also sounds funny, but who needs brakes?

[Scott Cee AKA 2drx4]

That is very promising if it runs and sounds healthy. Might just need some basic maintenance to get it to start properly on its own.

[Joe_the_ice_man]

Well, I'm usually not one to cave to peer pressure, but people are slowly convincing me to not tear apart the truck. Guess I might put the bus on the back burner for a bit and build a tow rig first.

To be entirely fair, it is the only vehicle I own without at least one rust hole...

I dumped the "fluid" out of the rear diff, and refilled it with oil, hopefully now it will be mobile when it's cold. I say fluid because I probably got about a gallon and a half of clear water before the nasty white oil started coming out...I'll have to stick a bore scope down the breather hole and see what the diff looks like when my breather shows up. Fortunately the water wasnt anywhere near air (rear end takes just over 17 liters of oil ). I also discovered that at some point someone put in a locker. It behaves kinda like a lunch box, so I assume it's an Eaton No Slip as the only factory option was an air locker. Kinda a bonus as long as all the water didn't wreck anything.

Rear suspension is also gonna need some love in the form of new air ride crap. The bags hold air, but look pretty dry rotted, and the ride height valve only "works" if you wiggle it just right. I also want to add a manual dump to it, as well as pressure gauges for the tank and suspension.

[Joe_the_ice_man]

Also having run the engine up to temperature a few times it spins up and starts nice. I guess I just needed to get it primed and spinning fast enough. It started at about -5 the other day on just the intake heater with minimal cranking and almost no smoke. That makes me a happy camper.

Also it turns out it's the 330hp and 860 ft. lb version, which supposedly was only for firetrucks and RVs, but maybe they were easier to get in Canada.

[Joe_the_ice_man]

Been fixing little things. Dumped the oil and gave it some proper filters. Fortunately I have the shallow sumped version, so it only takes 5 gallons of oil.

Relaced a worn out spring in the ride height valve to get it working. (Plastic wearing through metal is turning out to be a theme on this thing.)

I retaped the hole in the intercooler piping I found while fixing the tach

Its only supposed to be a 25psi wastegate...I'm sure the tape will hold

Also got the tach working...mostly. it seems at some point in time someone had either unhooked/replace the alternator and missed the little purple wire on the small terminal furthest inboard the alternator. Apparently it's an "R" terminal or something, I'm not sure what it does, but I assume it's an AC pulse or something. Tach still does goofy things for the first couple of seconds, but it smartens up after a moment.

[Joe_the_ice_man]

Seat was kinda worn out, so I been working on retrofitting a (Ford, I'll probably regret that) driver seat. I figured as a tow rig, imma want comfort, cause theres a reason I'm not driving a wheeler. Had a seat from a loaded Explorer lying around, so begins the shoehorn process.

I wanted to keep all the ritzy power and heat options for the new seat, but also the air ride of the old, turns out that wasnt hard, as the old seat rails just bolted to the top of the air ride system.

So with a little massaging from a sawzall and a die grinder I came up with this. Dont judge my welding, that welder is crap and I didnt feel like setting up a better one on Christmas.

That picture is after I cut out the magic witchcraft box that *Ford* put in there.

. I didn't feel like figuring out how to make the electronic presets work, so I just cut out the box and wired it for just normal electric controls. I've also paired the input wiring down to 5 total wires from the truck, power for the seat, power for the lumbar, 2x power for the heated seat, and a common ground.

Now I just gotta dig out the upfitters manual I found and see where I can pull some aux power to run all that junk.

[Joe_the_ice_man]

Putting off the bus build for the moment. Main reason is that a bus with a 3126 is a whole lot cheaper than a truck. Imma watch the budget and the Kijiji for when the right deal comes along. Especially now that I *shouldn't* have to drag it home with a half ton

[Scott Cee AKA 2drx4]

The alternator R terminal is exactly what you think, it's an AC voltage output for a tach signal. Some odd fluctuations on startup is fairly common with them. It's the easiest way to get a reliable tach signal on a mechanical diesel.

And yeah, I think it makes sense to keep the truck a truck. There definitely is more diesel busses out there, and they can be affordable.

[Joe_the_ice_man]

The alternator R terminal is exactly what you think, it's an AC voltage output for a tach signal. Some odd fluctuations on startup is fairly common with them. It's the easiest way to get a reliable tach signal on a mechanical diesel.

Well that's good to know. I think it's kinda goofy that GM decided to go that route, especially considering that Cat put a programmable tach output in the ECM...but I like simple, and electric is better than electronic most of the time. I assume GM just wanted to keep the base truck as similar as possible between engines, and I don't think the 3116 had an electronic tach output, being the beginning of Cat making "small" displacement electronic engines. I did have a good chuckle when I realised that each cylinder had about the same displacement as a Samurai

[Joe_the_ice_man]

Finished jamming the seat in and wiring power for the rails.

Spoiler alert, its tall.

I dont know if it tall enough to be an issue yet, I did take it for a quick burn around the subdivision, (with a little more confidence now that I have a tach and can kinda tell when to shift) and it seemed to be OK with the seat all the way down and the air ride half way up. It is a whole lot more comfortable than the stock one.