Stewart and Stevenson for an Overland Camper?

[Diversified_shenanigans]

Regarding the reliability and maintenance:

These trucks are on par with a semi.. The operating costs, maintenance expense, tools all fall very near that of a big rig.

If you want to know what it cost to run one, that's a good base line to research. Granted, most won't see that sort of mileage.

As mentioned above, if you spend the money going in to bring the rig up to par and maintain it....it's a million mile rig. But it won't be like servicing your glamper van a Quicklube for $39.95 a year. You can easily spend a grand on annual service (more if you just spin into the CAT dealer).

A lot of these trucks started out life being driven by 18 y/o crazy kids. And a lot of what got put out to pasture were trucks that the motorpool guys said "nope, nope, nope.......start pulling parts off this one". So some need more love and attention than others.

I get that this covers mostly, if not all, the engine/transmission aspects of the truck, but what about the components such as the airlift cab, the crane(?) for moving the spare tire, etc.?

I feel like the engine and tranny are Cummins reliable, but I’m still curious about the durability/reliability of the smaller parts. Will these hold up in between service intervals and while doing 1000+ mile trips on the interstate? Will the breakage of the smaller parts leave me stranded?

 

[Diversified_shenanigans]

4x4 vs 6x6

The 4x4 can actually fit in most parking spots. They turn in the same radius as an F350. They fit easier in a standard driveway as well. Advantages if a daily driver. Less maint of course and 2 fewer new tires to purchase.

The 6x6 have several advantages as well. Wee bit harder to get stuck, and a bette driveline angle in the rear (the M1078's are notoriously prone to vibration issues from the sharp down angle of attack the rear drive shaft takes....exception being the A1R 4x4 trucks with were the last of the line and very rare). Supposedly the 6x6 are a bit more thirsty when it comes to fuel (my old M1078 A1 got 7 mpg but my C7 M1079 only gets 5mpg). None of these trucks are cheap to feed going cross country.

Would you say there is stability gained on the highway when at speed by going with the 6x6? Or would the 4x4 hold its own rather well in terms of highway speed stability?
(I know there’s much more of an impact tonnage when relating 4x4 vs 6x6, but I would like to resolve the stability aspect first)

I ask from the mentality of SRW vs DRW in relationship to pickup trucks.

 

[ckouba]

I ask from the mentality of SRW vs DRW in relationship to pickup trucks.

My frame of reference is a 2013 3500 Crew Cab DRW Ram and my M1088. They are light years apart in terms of driving experience, although both feel remarkably stable. That said, all the weight in my camper box is low down near the chassis. It may change some when I load the box up with expedition-y stuff.

 

[Mullaney]

I get that this covers mostly, if not all, the engine/transmission aspects of the truck, but what about the components such as the airlift cab, the crane(?) for moving the spare tire, etc.?

I feel like the engine and tranny are Cummins reliable, but I’m still curious about the durability/reliability of the smaller parts. Will these hold up in between service intervals and while doing 1000+ mile trips on the interstate? Will the breakage of the smaller parts leave me stranded?

.
The smaller parts like the tire lift are okay. The key for these vehicles is maintenance. Most of them have been sitting out in the desert for a few years - and we really don't know how (why) they were sidelined (parked). The cab jack and the tire lift can be operated two ways. One is "air over hydraulic" and the other part of that system is a simple manual hydraulic jack. There are rebuild kits for all the tiny O-Rings and because of age I suggest you rebuild them. Very much like a 20 year old pickup, a little attention to some maintenance will go a long way. READ THE MANUAL on how to safely operate both of these components. The cab could mash you like a bug and the tire lift could break arms, legs or your scull if you don't spend some quality time "hitting the books".

There are two rubber "cab supports" behind the grill on the 4x4 and 6x6 "Stewarts". Those need to be replaced. They are old and tired and dry-rotted by now. Again, simple maintenance that needs to be done. You will be amazed how much better the truck will ride. Speaking of ride quality, there are two small air suspension bags on the back of the cab. Mine have worked perfectly since I got those two trucks. Your mileage may vary. Some folks here have had to replace their air bags.

There is a PPB (Polarity Protection Box) that is hidden under the spare tire when it is in the stored position. All the battery wiring from the battery box to the cab flows through that box. They either work or they don't. Again routine maintenance says a 20 year old truck needs to have all the battery connections cleaned including that PPB.

That brings to mind that the batteries that you might need to replace could be replaced with 2 rather than 4. Lots of information about that here on the site. And cleaning and using oxidation paste on everything will make your vehicle more reliable. Looking on the passenger dash side of the truck will entertain you with hours of maintenance that should be done on the fuse box.

 

[Third From Texas]

I get that this covers mostly, if not all, the engine/transmission aspects of the truck, but what about the components such as the airlift cab, the crane(?) for moving the spare tire, etc.?

I feel like the engine and tranny are Cummins reliable, but I’m still curious about the durability/reliability of the smaller parts. Will these hold up in between service intervals and while doing 1000+ mile trips on the interstate? Will the breakage of the smaller parts leave me stranded?

Part of the refresh process when you get the truck, typically. The two main culprits are the cab latch ($30 o-ring kit) and the hydraulic pump ($60 rebuild kit). The kits are readily available and simple to rebuild the pump (which often has failed/leaks due to sitting). The cab and spare cylinders themselves are pretty tough units. Most of the time simple issues like air in the line (from the truck sitting for years) can be resolved simply by refilling and bleeding. But for the most part, the systems are pretty tough and once maintained and kept topped off will last the life of the rig.

A good rule of thumb is to plan on replacing pretty much all the rubber bits that have weathered the elements over the 20 or so years. Rubber dies with age. So always look to new (often civilian or custom made) solutions over some NOS (ie: new surplus) rubber that has sat on a shelf for that same 20 years. Rubber lasts about 8 years before it can start breaking down. Things like cab bushings, swaybar bushings you will want to replace before hitting the road any great distance. They may "look" intact, but once you start applying pressure to them they disintegrate quickly.

Most of these trucks have the newer fan clutch/mounts. A few of the older trucks may not have gotten the upgrade though. It's important to check (and easy spot test) to confirm. Else you can put the fan thru the radiator (as happened to the owner of my first M1078 . There is also a small metal oil line that is prone to failure, but it's an easy fix if inspection warrants such. I can lead to engine failure if left unchecked, though.

There are a few other things you want to check before a long haul. Like the compressor bracket which is surprisingly often loose and can start bouncing enound and crack things the engine casing where it's mounted too. U-joint play, etc. A few other things like that that, but most are simple spot checks with a wrench.

edit: I should have read all the replies so as not to repeat stuff. LOL

 

[Third From Texas]

Would you say there is stability gained on the highway when at speed by going with the 6x6? Or would the 4x4 hold its own rather well in terms of highway speed stability?
(I know there’s much more of an impact tonnage when relating 4x4 vs 6x6, but I would like to resolve the stability aspect first)

I ask from the mentality of SRW vs DRW in relationship to pickup trucks.

I've honestly never driven a 6x6 FMTV. I can tell you that the 4x4 handles like any other big pickup truck going down the road. It's hard to compare to a dually, but more about payload capacity than stability (and I don't know if you've seen one of these 396 tires in person, but they are big, fat, f*****s). LOL

Tires are a consideration, though. Some trucks still have the Michelin "may-pops" on them where others got the far safer Goodyears. The general consensus is to lose the "may-pops" or experience the joys of a blowout in a 25,000 pound truck. But of course any tire that's sat outside under a parked truck for 20+ years needs a solid inspection. Tires are a considerable expense. You can often get used, but I've seen dry rotted tires sold all the time (both at auction and by surplus "flippers". You can often pick up a set of MRAP tires for $1200 out of CA via GovPlanet but keep in mind shipping and remounting them). You will often see folks ask tire about date codes and while not the definitive, they are a good reference point when you cannot kick the tire in-person. But new from Goodyear will run about $3K a pop for the actual milspec tires. And another consideration: do you want to buy four our six at that price.

I'd say that the choice between 4x and 6x would be the size of your habitat. Myself and the dog fit fin in a 12' box and I really don't need more room, so the 4x was a perfect fit. *my FMTV is my daily driver and only street legal vehicle I've owned for the past six years.

 

[Third From Texas]

One thing I will mention because because I feel it should be stated. It's the true Achilles heel of these trucks.

They are not four-wheel-drive or six-wheel-drive. They are all-wheel-drive.

Basically if you lose traction on both axels, you'll have two tires spinning and the two that are stuck sitting there like anchors. No traction, they stop turning. And it sucks. You can add Detroit-style lockers but no manual hubs or air lockers for these trucks.

Military logic: "why spec lockers when we can have a million dollar tow truck follow everyone around?"

This is likely where the 6x6 shines by having an extra axel to get you out of the s***. But they too can suffer the same fate and owners often slap lockers in them as well.

But as I said, you can slap an $800 locker in the rear and become a full time 3x and "three outta four ain't bad". I do a LOT of deep sand driving and while I've only ever had to bust out a shovel once in hundreds of adventures, it was a wakeup call. I plan to add a rear locker and a Sherpa Stallion for safe measure (and because I hate shovels).

 

[NVDiveguy]

I see the thread and I'm sure it will become more relevant as I go on my journey more. Now that I have some my initial questions answered, I'll focus first on what size box I'll need, weighing 2.5 ton vs 5 ton pros/cons, and how I'll go about buying a truck.

I have civilianized a M1078. I took care of all of the issues it had coming from the auction. I have titled and registered it in NV. I have decided to go with a 6x6 for a number of reasons. I have set my sights on one up for auction so I am looking to sell my M1078.

I agree that they will make a GREAT platform for an overland RV.