MTV 1084 w/MHC Hay Feeding Truck Conversion

I just got my first MV on Govplanet and am trying to make an ultimate cow feeding machine out of it. I'm going to mount a feeder on the bed and load bales with the crane etc, that part should be pretty easy and fun.

The truck on the other hand is certainly like no CV I've ever worked on. I have heard these are electrical nightmares and from the start mine has been a pain. I have a drain on the battery somewhere so I have to disconnect the terminals after I shut down, and the starter had the common problem where it would just click instead of turning over. I probably rushed in too fast and got a new starter and put it in, but it didn't solve the issue at all. When I hotwired the K1 relay north-south, it cranks over fine. Ive tried lots of different relays in that position, nothing seems to help. When I push the start switch and test the voltage on the signal wires, they are 24v, I can't seem to get that signal to shake or waver, even though it acts like a wire is loose in it when I try to crank.

So, I just bypassed the relay and hooked the switch up to the top and bottom terminals on K1 and it works great. Is there any reason why this wouldn't be safe? Passenger cars don't use starter relays typically, you just turn the key.

I would ultimately like to strip the electrical system down to just the bare bones, I am looking for reliability primarily. I don't need a chemical detector or blackout lights, and I defintely don't need a start inhibit that will prevent me from starting the rig if either the switch is pressed or the start inhibit relay is bad. I mean honestly, why would anyone want that. Just pinch a fuel line off with vice grips.....

Anyway, has anyone done a build like this before? I don't want to start ripping things out that it turns out are important somehow but I would love to do away with lots of the junk, specifically the start inhibit and the confusing battery cable routing, and all the pointless systems I will never use (blackout) but those systems are probably most easily eliminated by just pulling the fuse.

The truck is in really good shape, and my only other issue so far is that it starts worse than my old tractors. In 50 degree weather where my diesel trucks and semis would pop right off, this 3116 coughs and sputters and piddles around for a solid 10 seconds before it gets going, and its far worse in the cold. I would say its the equivalent of my 99 dodge 24v cummins when its right about 0 outside. Is this normal for these engines? I ordered a block heater and might put a pan heater on as well, but I'm a little worried it won't start at all if it gets actually cold. I'm in Montana, if this won't start in the -20 region its as useless as tits on a bull. Motor has 30k on it, visually looks pretty good on the outside. Never seen oil so clean in a diesel in my life.

you have an air leak in the fuel system, the likely culprate is the primary fuel filter. as for the electrical you might think there is more wires than it needs,and you are probably right. if you leave it this way and fix what is wrong you will always have a road map in the tm to follow to do repairs. if you make it your way than troubleshooting problems down the road is going to be a pain. as a general rule folks who try to make their own harnesses usually have less reliability than factory wiring. where I live mine is starting with out a block heater down to 0 right now with a push of the eather button. The 3116 is a low pressure injection system like the old 855 cummins and will start in the cold that way. At 50 you should just have to bump the starter and it will start up.

I’ll check the fuel lines and see if I can find a leak. Tricky to locate those without a clear hose or filter somewhere. Maybe there’s a bleeder nut on a filter housing?

As for the wiring I don’t want to make my own harness but I do want to remove components preemptively when I have the time to do so. When my hands are freezing and 20 miles from home and I’m banging on components with a crescent wrench trying to get the truck to work isn’t how I want to spend my winter. I agree that the more I deviate from factory wiring it gets more risky. But if I’m careful and clearly document any modifications I could always restore it to factory. For example the start inhibit shuts off power to the fuel pump as far as I can tell. If I can find out how that works there must be a wire I can cut somewhere handy day on the pump itself? Or maybe there’s a harness plug in that you can just disconnect. I don’t know, but with everybody claiming them to be such electrical hassles I figured somebody might have already tried a build like this.

If you really want to hack at it, all the wiring schematics are in the TM.

I echo the others though, leave the truck as it is and just put it in good repair, and it will be reliable. If you pull the fuse panel and dash panels up you will be horrified by the anonymous sea of white cables but at the end of the day if you go through your relays, fuses, and grounds (corrosion) once, and check the usual wear spots in the bundles, the truck can be expected to work well for a long time. Other than the start system there is not much to go wrong that is going to strand you.

Homegrown wiring harnesses are a recipe for disaster unless they are expertly made because they are corrosion magnets. Building a vehicle wiring harness that won't ingress water into the cable insulation and eventually have problems is a real art, and also expensive. Maybe it's even an art you possess and will do it properly. I think we've all seen it go wrong too many times though.

When you review the schematics in the TM you'll probably see it's actually pretty straightforward and there isn't really that much to simplify. You shouldn't have a current drain but that should be easy to run down by pulling the fuses/breakers and going through with an ammeter. My truck pulls basically nothing when the rocker switch is off.

The trucks, imo, are not electrical nightmares. The issue if you want to call it that seems to be that people buy the LMTVs that were missing door glass or more commonly missing the turret lids. Then water gets into the dash and you get corrosion on the fuse panel block and in the wiring crimps and things. In turn, you have problems. This isn't a design issue, it's just an ownership issue. There are also a couple of places under the dash where the bundles can rub and wear holes, if you poke around with a flashlight you'll be able to see if everything is right or not. But just pull the panels and have a look and see what you're starting from. My truck was clean thankfully - just a bit of sand in the dash, but it looked like it was always dry.

It seems like I hear as many people saying they aren't electrical issues as people that say the opposite.

Perhaps I should temper my plans to create a lot of extra work for myself and just pull fuses in systems I don't plan to use and install a power shut-off switch for insurance, which I have on most of my other heavy trucks and equipment.

I have already rewired the starter to bypass the relay. I worked on it for an entire day and got nowhere in terms of stopping the clicking, and unless somebody has an idea for how to solve that, I think it will have to remain. I do want to remove the start inhibit system, as I have already had some issues with it. Finally, I think rewiring the main battery cables will be worth while for two reasons. First, the batteries in it are acting a little weak and if I replace them it is vastly cheaper to buy 2 8Ds than four of the 6TLs. Second, many of the battery cables are melted at the terminals and get excessively hot with only a short period of cranking IMO. Shortening and simplifying/replacing the cables should improve this?

Outside of that, I would be fine with leaving the rest of the system as is. My truck looks quite clean, so signs of any leakage or damage in the wiring under the dash.

Back to the poor start, what are the chances that this truck has been ether broken and needs a dose to start all the time? I've worked with older tractors that will hesitate to start on a summer morning without a shot of ether. Does anyone put grid heaters in these trucks to replace the ether start?

I haven't heard of anyone putting a grid heater in, but coolant heaters are popular with the folks in colder climates. In good tune the truck should start immediately in decent weather and freezing or below without ether it aught to catch quickly, stumble a bit, and then run well when it warms up. If your truck is acting worse (it seems to be a spectrum when they come out of auction) you probably have a problem you need to run down. My record is a -40 degree start, no ether, no problems. Turned over for 4-5 seconds, caught, stumbled for 5-10, and I pulled it onto the highway. Telling you this just for a reference of how they ought to be. I've heard about guys with trucks that need ether or are generally a nightmare to start in the cold, but this shouldn't be.

It's helpful if you add your truck to your signature so we know what you've got, but if it's an A0 era with the 3116, the fuel systems, racks, injectors, etc in those are persnickity. Consensus seems to be it's a real art to get them right. They also burn out the #5 valve when they are out of whack, it's a disease. So you might find it worthwhile to take the engine by a cat place if you can find one that has a guy with the touch to set a 3116. They are good engines when they are in tune, and bad engines when they are not... Lots of information about that around the net. May be related if you are having mechanical start issues.

The crane power could be staying on and draining your batts it does not turn off with the dash switch. There is a switch on the box center left if you are standing behind the truck facing the crane.

I'll figure out the signature line here in a bit, but yes, its a 1997 Model 3116 Cat. For the electrical, jury is still out on the batteries and cables, but I bought a bunch of 24V 5pins on amazon did a mass relay replacement and that has pretty much cleared up my intermittent electrical problems.
I have been turning the crane switch off, so it isn't that, but I will try to track down the current drain tomorrow by pulling individual fuses.

My record is a -40 degree start, no ether, no problems.

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I installed a block heater (which was super easy and highly recommended for anyone thinking about doing that) and did some experiments with starting. Inmy experience, diesels without glow plugs or an intake heater which this appears to have neither, don't start worth a darn in anything thats moderately cold. You will need ether at 0F, or good luck and a jumper cable to extend your crank time. -40F sounds like a pure miracle. I don't have high expectations for its starting, but it need improvement.

When I have it plugged in it starts instantly, like perhaps the fastest start I've ever seen. I had a thought that maybe I'm not getting enough voltage from my maybe-not-great batteries in the cold to get fuel injection going, but since its all mechanical that doesn't make much sense. If I don't have it plugged in, in 30 degree weather, it will start without ether, but after 5-10 seconds of cranking and then will cough and sputter for a solid 15-20 seconds. It almost never dies in this phase but it comes as close as it could. It seems to be slightly improved from when I first starting working on it though.

A fast, plugged in start should rule out an air leak in the lines, because after sitting over night it would have to crank through the air even if the block was warmed up and should take some extra cranking time.

I don't particularly want to take this down to have a Cat mech work on it at probably.....$125/hr but as a last resort I guess that's an option. Hopefully I can keep banging my head on things in my shop and discover something. Either that or just cheat and put an intake heater on. I see they were commonly installed on the 3116s.

turn the fuel up on it. The 1084 i have here was turned down almost 3 turns below the stock setting. It would spit, sputter and cloud up and run really rough when it is cold out. I turned it up about 6 turns total. it fires up now in 30 degree in the 2nd spin over and sounds fine now.

simp5782 said:

turn the fuel up on it. The 1084 i have here was turned down almost 3 turns below the stock setting. It would spit, sputter and cloud up and run really rough when it is cold out. I turned it up about 6 turns total. it fires up now in 30 degree in the 2nd spin over and sounds fine now.

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Do you have any tips on how to do that? And how do I know what the stock setting is?

Is it gutless? Every 1084 I've drove has fell flat on its face off the start.


https://youtu.be/1YtbqKv0828

That looks fairly straightforward. Hard to know where the adjustment is at now though.

I haven't driven anything similar, so I can't say for sure. It certainly isn't overpowered, but they are awfully heavy empty with a reasonably small motor so I didn't expect it to come flying off the line. I feel like it has enough power, but the transmission shifts....frustratingly. When it grabs a gear right I seem to take off pretty well.

cowhock35 said:

That looks fairly straightforward. Hard to know where the adjustment is at now though.

I haven't driven anything similar, so I can't say for sure. It certainly isn't overpowered, but they are awfully heavy empty with a reasonably small motor so I didn't expect it to come flying off the line. I feel like it has enough power, but the transmission shifts....frustratingly. When it grabs a gear right I seem to take off pretty well.

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Adjust your throttle cable up.

To help the trans shift better? I would have to drive it a little more to determine if there is something wrong or out of adjustment on it. I just kinda figured this is how an auto would be in a heavy truck...pretty sluggish and often not in the gear you want it in, but at least you have an available hand all the time.

Well, I really did it this time. I noticed that the trans will lock out if the PTO switch is turned on and for my application I need to be able to drive while operating the PTO. Figured it might be a sensor or something that was just wired into the PTO switch so I disconnected the pins and started probing around with a jumper trying to get the light to come on and see which of the pairs was the connection to turn the PTO itself on. Well.....It popped and crackled and lightly welded the end of my jumper to one of the pins and it took about a second for me to yank it off and now the transmission display won't turn on. I checked fuses in the VIM and fuses on the main panel. I'm astonished as fuse and relay generous they were on these trucks that I would be able to fry the trans ECM, but its looking that way to me. Anyone have any advice or troubleshooting tips from here before I send the ECM off for testing and repair?

The wtec2 pinout is online. See if there is power to the tcm. The pto runs at a higher rpm than the transmission is designed to shift at. You can’t have it both ways. Say the pto is intended to run around 1700rpms you can’t shift into gear at that rpm and if you go down to 600rpms it’s not really enough to run the pto. If you want to run hydraulics and drive then you will have to install a pony motor with its own separate pto.

Suprman said:

The wtec2 pinout is online. See if there is power to the tcm. The pto runs at a higher rpm than the transmission is designed to shift at. You can’t have it both ways. Say the pto is intended to run around 1700rpms you can’t shift into gear at that rpm and if you go down to 600rpms it’s not really enough to run the pto. If you want to run hydraulics and drive then you will have to install a pony motor with its own separate pto.

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I don't need to drive fast, just creep at a 2-3 MPH, but I absolutely have to be able to move with the PTO running. I've been running the PTO at idle for most of my testing and it doesn't seem to affect it. If it was truly a pinch I think I could make do with electric/hydraulic but I would defintely prefer to make this work. My neighbor has a 7 speed allison auto in his bale picker truck and drives with the PTO on all the time, so I don't think it should be an issue. I don't think his is a WTEC2 though, its a little newer truck, 2003 or so.

The TCM is installed under the dash behind/connected-to the shift module right?

The wtec2 keypad and computer are screwed together in the dash. The pto is driven off a ring gear in the transmission that spins at engine speed. Engine would have to be at idle to shift even if you defeated the pto lockout. The trans control wont allow shifting over a set rpm to prevent damage. A real hay baler truck is probably designed so that the hydraulics work when moving.

Does the transfer case on these trucks allow for a PTO setup like the 5 ton wrecker or the PLS trucks? I assume the 1089s run off the transmission PTO as well. I know can use those at a slow creep speed while it is engaged and not hurt it.

If you want to run a PTO off the transmission you may have to find a way to go to a manual system for the PTO. or simply what will said a pony motor with pump would be the easiest.

No tcase output for pto. Just the ring gear/pto port on the side of the trans. Electric hyd usually has a duty cycle.