M1031 Build Thread

[hrbergeron]

I’m starting this build thread to keep myself reminded of what I’ve done to the vehicle and plans I have for the vehicle. When I can, I try to help people on this site with their vehicles, and one of the best ways I have learned how to do something for my military vehicles is simply observing others’ build threads. Hopefully, this will help someone with their build like others helped mine. PICTURES help me much more than anything, and I try to take pictures to show what I’ve done.

This is going in the “CUCV Hot Rodding and Modification” thread because I will be doing several taboo non-stock mods to this vehicle because I plan on keeping it for a long time.

To start, I have previously restored a M1009 CUCV and several other MVs.



When I first got into this hobby, my father strongly recommended I purchase a CUCV contact maintenance truck. It only took 5 years for me to finally listen to him and get one.

I purchased this 1986 M1031 off GovDeals from a small county in Georgia, and, as usual, the pictures were terrible at showing condition of the vehicle. It was sold as INOP, “Needs high pressure fuel pump. Truck was running until pump went out.” The auction price it sold for reflected the operational status.



The pick-up started bad as I had issues with the winch on my trailer. Something I hadn’t seen before, the winch power cables corroded internally to literally dust and I had to cut around 2 feet off each end to find clean wire to send to the battery terminals. What I found odd is that I used the winch less than a week earlier without issue. Other than that, pick-up and loading was uneventful. (You may notice that the vehicle is loaded all the way to the front of the trailer. I had a load to pick-up afterwards that went behind the CUCV and distributed the tongue weight back.)

 

[hrbergeron]

Once I got home and started doing an overview of the vehicle, I noticed some irregularities. A pleasant surprise, the motor was replaced with a HMMWV 6.5L GEP motor back in 2010. The other main irregularity was that the vehicle was on 37” HMMWV MT/Rs. To do this, the military put different rims on to fit 16.5R tires. The starter was replaced at some time with a new style gear reduction model, but was missing the support bracket.



According to the county sheriff I picked up the CUCV from, they received it around 2016 and the vehicle had been INOP since 2018 and the county lacked the funds to fix it. So I guess this CUCV was in service from 1986-2016ish, which is an incredible service life of a military vehicle

 

[hrbergeron]

I started work on the vehicle by diagnosing why they could not get the motor running. My first issue was getting the starter to work. I could hear the relay click, but there was no voltage going to the starter solenoid ignition terminal. So, I automatically assumed the relay was bad and installed the “Doghead” mod as everyone else does. This accomplished nothing aside from a much more audible relay click. After 2 hours in total, I discovered someone bypassed the relay by a push button on the side of the dash. I discovered this by tracing the ENTIRE starter solenoid ignition wire.



So, all this work just to be able to turn the engine over to diagnose why the motor didn’t run! Originally couldn’t get any fuel out of the fuel filter bleeder valve, so I checked the fuel level. The gauge said ¼ full, but I decided to add some fresh diesel to the tank and could hear the diesel hitting the bare bottom of the tank. Once I put about 5 gallons in, there was fuel coming out of the filter valve. I then moved to the injection pump. There was zero fuel going to any of the injectors. I checked to make sure the fuel supply lines were clear and they were.

 

[hrbergeron]

I purchased this vehicle expecting to put a $50 fuel pump in it and have a decent vehicle. Instead, I had to replace a $700 injection pump. I had a spare core IP in my parts bin and I took it to the best rebuilder in the area (which does most all of the local military IP rebuilds).

The 6.5GEP had a CUCV IP installed, so I got to thinking, “well it doesn’t matter if you have a 6.5L GEP motor in there, if you have a regular CUCV injection pump on there that motor will run on 6.2L specs.” The local rebuilders are great at their job and I had them rebuild it to 6.5L specs. I’m not an expert on IPs, but it effects the actual fuel delivery amount and other tuning. While changing everything over from the other pump, I discovered the TPS was broken. Interestingly, the new one I bought off eBay was made in 2010 and had the military NSN data label on it.



Out with the old, in with the new.

(note that in the picture I had the throttle pushrod installed on the wrong side, causing the engine rpm to max out)

While bleeding the new IP, the starter died. Work shut down on the vehicle for 2 days until the new starter arrived in the mail along with the support bracket. I needed to drop the starter anyways because the starter support bracket was missing so it wasn’t a big deal. Installed the new starter and a minute or two later the motor was running. (Note the push button start in the video)

 

[hrbergeron]

What’s next? The glow plug system doesn’t work at all. Haven’t started diagnosing the system yet. The 24v system is working properly. There is rust at the top of the rockers and the cab corners are rusted out. The fenders were cut to fit the 37s and they are damaged. The doors are damaged too. There are components missing for the PTO generator relay panel. The truck seems to drive fine and shift properly. The brakes are extremely firm, probably because someone swapped the brake fluid to DOT3 over DOT5. I will replace the rotors, pads, calipers, front rubber lines, and rear drums because I don’t trust any braking component that is 35 years old.

I haven’t decided if I’m keeping the 37s on this vehicle. I know if I do, I will want to do it properly with a 4” lift.

 

[hrbergeron]

A contact of mine had a CUCV generator, control panel, and relay panel for sale. One of my relays was missing and their panel had it. Sadly for me they wanted to keep everything together, so I now have an extra generator, control panel, and relay panel. I’ve read some on here about an updated relay programmed by a member on SS, but I’ll try this first and see if it works. If it doesn’t, well, I’ll still have these extra parts. I also picked up a new undamaged front bumper and brush guard from the same person to replace this one with.

 

[hrbergeron]

I started to calculate the amount of hours required to fix the rust and damage to the cab, fenders, etc and came to the realization it would be easier to just replace the whole part. I’m purchasing a squarebody dually from a friend of mine next week and going to swap the whole cab, fenders, etc. onto the CUCV. Aside from the rust on the hood, there is no rust on the rest of the body. This truck spent most of its life in Texas. The mirrors will stay on the doors, I think they’ll work better than the stock CUCV ones because I have the maintenance body on the back. I’m not a fan of the roof clearance lights, but oh well. This dually has factory AC, so I will be figuring out somehow to run AC in my 1031.

 

[Recovry4x4]

That cab and chassis rear would turn your SECM into a nice looking dually. You already have 6 rims.

 

[Skinny]

Nice! Nothing taboo here...just some honest CUCV wrenching.

Do yourself a favor and scrap all of that stock generator controller stuff. Very unreliable and complex. A member on here sells a new unit which works great and is worth the money. You can install one yourself but requires programming and wiring. Completely doable but for not much more money you can just get one that is turn key.

To run AC you have a few options. Get one of those wonkey brackets to fit the compressor on the passenger side which sticks way out and is ugly.

Convert to 12v and use a civilian setup which it sounds like you already have that. Note that this set up uses the pancake compressor which sucks brand new. You wont find many people that like the A4 compressor.

Convert to M1010 brackets. This will let you run 12 or 24 volt. You will need to source one or two J180 alternators. Leece Neville self exciting 160a units run about $175 each and are burly. The factory Frigidaire A6 compressor moved a ton of refrigerant at idle but they suffer from a seal leak that is tough to resolve. If you go that route plan on stopping off every season. Sanden makes a drop in A6 replacement which I have. No extra brackets. Drops right into the A6 set up and is brand new.

You can use the a factory evaporator and controls from a civy truck. Will just need to fab up new lines which is easy. I put bucket seats in my truck and out a backhoe unit on the back of the cab. That way I didn't have to get my dash and it cools better. All are different options.

Hope this helps...

Sent from my Moto G (5) Plus using Tapatalk

 

[Recovry4x4]

If you were to go the ambulance path that Skinny mentioned, this thread has valuable information on the install. Chevyc60 posted on there and he did my ambulance when I had it. Charging was never an issue in the 6 years I owned it. I think this would be the most robust way to accomplish what you seek.

 

[Curtisje]

If you were to go the ambulance path that Skinny mentioned, this thread has valuable information on the install. Chevyc60 posted on there and he did my ambulance when I had it. Charging was never an issue in the 6 years I owned it. I think this would be the most robust way to accomplish what you seek.

I wish I had read that before I rebuilt my alternators.

 

[hrbergeron]

If you were to go the ambulance path that Skinny mentioned, this thread has valuable information on the install. Chevyc60 posted on there and he did my ambulance when I had it. Charging was never an issue in the 6 years I owned it. I think this would be the most robust way to accomplish what you seek.

That's what I'm planning on doing, swapping an ambulance system into mine. I found a person that is parting out a CUCV M1010 and I'm getting the compressor, brackets, etc, but someone had swapped the truck to 12v and removed the brackets for the passenger side alternators and replaced them with a standard alternator and bracket.

So, I need to source something for the alternator(s) because I want to keep the truck 24v

 

[hrbergeron]

That cab and chassis rear would turn your SECM into a nice looking dually. You already have 6 rims.

It could... but the frame on that dually was torched. So I would have to swap the axles if I really wanted it to be a dually.

 

[hrbergeron]

Nice! Nothing taboo here...just some honest CUCV wrenching.

Do yourself a favor and scrap all of that stock generator controller stuff. Very unreliable and complex. A member on here sells a new unit which works great and is worth the money. You can install one yourself but requires programming and wiring. Completely doable but for not much more money you can just get one that is turn key.

Thank you for the writeup of options. I've probably scrolled and read through about 6 hours of posts here on SS about AC systems and about M1031s. I have found info about the controller and I've messaged the member on here who programs them. Maybe they still do it.

 

[Skinny]

Yeah no worries. If you're have any questions let me know.

If I were to do this over again and didn't want to go to bucket seats or a backhoe evaporator I would do just the aftermarket dashboard evaporator. This would give you defrost, dash, and foot doors that go full cold to hot.

Then do the Sanden A6 compressor with a modern R134 condensor. Mine has that with two fans which is superior low speed cooling then the stock Chevy R12 condensor.

Sent from my Moto G (5) Plus using Tapatalk

 

[Recovry4x4]

It could... but the frame on that dually was torched. So I would have to swap the axles if I really wanted it to be a dually.

That's what I was referring to. Should you decide to go that route, your existing gearset and NoSpin would swap over to the chassis cab rear end or if it had a favorable ratio, swap gears in the front. Then it's a simple hub/rotor swap in the front. I've done 2 this way so far. The other consideration is that your SECM body has a frame rail that would possibly interfere with the inner tire. I had to remove some material on mine but I have the older Dodge M887 body.

Hey James, sorry buddy!

 

[Mad Texan]

That's what I'm planning on doing, swapping an ambulance system into mine. I found a person that is parting out a CUCV M1010 and I'm getting the compressor, brackets, etc, but someone had swapped the truck to 12v and removed the brackets for the passenger side alternators and replaced them with a standard alternator and bracket.

So, I need to source something for the alternator(s) because I want to keep the truck 24v

Here is one of the brackets: https://www.ebay.com/itm/CUCV-Chevy...391660?hash=item2d0dc2b1ec:g:7OMAAOSwS3Za9vCf

 

[hrbergeron]

Here is one of the brackets:

Thanks! I just bought it. Now I need the other one.

 

[Jlprober]

I modded mine to nv4500 and got Doug from SS to program a Woodward Advanced Proportional Engine Control System APECS Model 4500. He sent me the wiring digram which helped alleviate alot of the Mil wiring down to just 5 or 6 wires. This removes all the transistor like components and makes it stupid proof. I wired mine up in an afternoon and it worked perfectly the first time.

The NV4500 trans swap is great when running the generator as i can pick the gear i want to run the generator for whatever load i am running at the time. In 5th gear with pto engaged the engine is running barely over idle at approximately 800-900 rpm. Thats based off of a rudimentary tach that has a mag pickup from one of the alts. And the gen stays steady at 60 Hz with no fluctuation, whereas before there was always an oscillation in rpms.

I've kept mine 24v and no A/C......i have other trucks i can keep cool in.

 

[rossbart]

I modded mine to nv4500 and got Doug from SS to program a Woodward Advanced Proportional Engine Control System APECS Model 4500. He sent me the wiring digram which helped alleviate alot of the Mil wiring down to just 5 or 6 wires. This removes all the transistor like components and makes it stupid proof. I wired mine up in an afternoon and it worked perfectly the first time.

The NV4500 trans swap is great when running the generator as i can pick the gear i want to run the generator for whatever load i am running at the time. In 5th gear with pto engaged the engine is running barely over idle at approximately 800-900 rpm. Thats based off of a rudimentary tach that has a mag pickup from one of the alts. And the gen stays steady at 60 Hz with no fluctuation, whereas before there was always an oscillation in rpms.

I've kept mine 24v and no A/C......i have other trucks i can keep cool in.

I’m super interested in getting one of these apecs controllers for a new M1031 that I’m trying to get working reliable as a farm service truck.
Very slick, rust free, tight truck. Just 32,000 miles and with a fresh 6.5. But, the generator is not dependable. Sometimes works perfect. Sometimes won’t govern at all. Sometimes won’t make electricity OR govern?
Any chance you could help me get in touch with the SS member that helped you out with the APECS controller?
Thanks in advance for any assistance...