things to look for M931A?

[yotawheeler]

Hello, I recently found a M931A?, not sure if its a 1 or 2 for sale at a price that I am having a tough time saying no to (he is asking about $9,000 USD). which i think is pretty good if the condition is as good as described.

The owner is not a "MV guy" and cant really tell me too many details about the truck other than its automatic, can go anywhere, only had a canvas top on it and he is saying that it was refurbished before he got it and that it has no leaks.....Its running super singles, no winch from what i can see but i don't know if it has the CTIS system on it or not. I am not able to see what the motor is either. 1985 MF date though. I recently got my class 1 (CDL) but I am still pretty green on what i should be looking for on a semi vs a standard pickup

-besides doing my standard Pre trip, what things should i be looking at specifically for this model that are known problem areas? if any

-I did manage to find a filter/parts list online and the OSHKOSH site lists lots of parts so I would imagine whatever i cant get up north in Canada, ill be able to order states side

-what is the hitch size on these trucks? I want to be able to drag commercial trailers -Van, highboy ect- I had seen on the oshkosh site there is a 2" and a 3.5". also, hitch height is a bit higher from what the seller tells me, i don't think this should generally be an issue other than the trailer not sitting exactly level right?

-when they do a factory refurb, do they put an extra sticker or placard on the vehicle to verify that its been done? or could a person contact the company -assuming it would be oshkosh doing the refurb?-

-i have heard not great things about the CTIS systems being expensive to fix and temperamental....would it be an issue to just bypass this system if/when it decides to give problems?

any advice or insight is much appreciated, I am pretty new to larger vehicles but have always wanted anything from a deuce all the way up to a M1070. this might just be the start of things for me.

 

[Jericho]

1.properly functioning brakes and sub systems, no air leaks or bypassed tanks in the air system
2. serviceable tires .
3. all lights and horn functioning.
4 engine starts and runs as normal, ie no abnormal noises temps pressures all within limits.
5.NO BIG TIME DEATH WOBBLE in the tires.
6.check all your fluid levels service as needed , check for leaks, missing hardware, torn wires ect.

fifth wheel will handle standard couplings, you can haul regular trailers . Depot work usually has a tag on the lower drivers door reinforcing channel , usually a RED RIVER MWO tag. CITS is not as bad as most make out, parts are available . easy to trouble shoot, all the tech data is here. to null out just disconnect the cannon plug in the cab near the shifter. delete kit is only 80$ or so DONT drive it on the high way until your used to it READ manual and get insurance , BRAKES are good but touchy read that section FIRST

 

[porkysplace]

Most of them were RRAD ( Red River Army Depot ) rebuilds .
Post #8 of this thread by wsucougarx tells what they did to them .
[h=1]RED River Army Depot[/h]A lot of your questions can be answered by reading this ( should be read by everyone before operating one ).
TM9-2320-211-10.pdf
TM9-2320-211-10 Operator's Manual for 5 ton M39 series trucks with multifuel engines.

 

[sandcobra164]

Since you have a CDL you know what to look for. Porkysplace gave some good advice of getting familiar with the Tech Manuals. Does it pass basic checks described in the PMCS (Preventative Maintenance Checks and Services) section. Oil in the engine and transmission, radiator surge tank full. Starts and runs, move onto builds air pressure displayed on both gauges? Moves fine under it's own power. Don't be discouraged by a RRAD truck, mixed experiences on here. Personally I own a never touched by any rebuild truck and aside from rough paint and surface rust it's a proven runner by 5,000 miles of use. It also leaks some oil here and there but I'd drive it to your house next week if I had a reason to.

 

[yotawheeler]

Hey guys, thank you for the advice so far! much appreciated. I do have the CDL so i do know to look for the things like air brake leak test, compressor building pressure, governor and all that sort of thing plus everything on the standard walk around, tires, cracks in the frame, leaks....

I was mostly curious if there was anything to specifically watch out for or avoid

I will certainly look at the tech manuals first. thank you for posting the hot link and I will check for the red river army depot sticker. is there any way to verify a full depot rebuild?

also, i was reading some info and history on these trucks and saw mention that many of them (possibly ALL?) were converted to an ABS braking system?

 

[porkysplace]

Hey guys, thank you for the advice so far! much appreciated. I do have the CDL so i do know to look for the things like air brake leak test, compressor building pressure, governor and all that sort of thing plus everything on the standard walk around, tires, cracks in the frame, leaks....

I was mostly curious if there was anything to specifically watch out for or avoid

I will certainly look at the tech manuals first. thank you for posting the hot link and I will check for the red river army depot sticker. is there any way to verify a full depot rebuild?

also, i was reading some info and history on these trucks and saw mention that many of them (possibly ALL?) were converted to an ABS braking system?

Some were released with out the ABS upgrade , this thread lists the MWO's post #24 shows the tags.
[h=1]M923 MWO Identification[/h]

 

[M813rc]

The military 5th wheel standard on these trucks is 2". It is tall because it can tilt in two axes - normal front/back, but can also tilt side to side for rough terrain crossing. There are wedges that lock this side to side out under normal use. Unless you haul in some extreme places, you will likely never need that tilt feature.

The frame rails are the same distance apart as civilian truck, so you can easily swap on a civilian 5th wheel. I did this with one of mine (added a Fontaine slider), which lowered the 5th wheel plate height by around 8". Fortuitously, several of the holes lined up, so there was a minimum of drilling.
The significance of this height drop for me was taking my M129A4 trailer nose height from 13'9" down to 13'1". The TSS is a similar height.
The slider allows more clearance for the rear wheels on short-necked trailers. My M128 would snag the landing gear feet on the rear tires under certain conditions, like turning off a flat road into a gently sloping driveway. Fortunately, those feet are hinged and can be strapped up on the back of the legs when traveling, however sliding the 5th wheel back one notch would eliminate the problem.
Oddly, the short little M146 shows no tendency to rub the landing gear.

When shifting from forwards to reverse and back, always pause in neutral, don't zoom through. Personally, my shift pause is something like forward-neutral two three-reverse.
Never use reverse in low range! The manual tells you this, and some who have not heeded the advice have seen large expensive parts of the truck literally fall out underneath.

Cheers

 

[yotawheeler]

The military 5th wheel standard on these trucks is 2". It is tall because it can tilt in two axes - normal front/back, but can also tilt side to side for rough terrain crossing. There are wedges that lock this side to side out under normal use. Unless you haul in some extreme places, you will likely never need that tilt feature.

The frame rails are the same distance apart as civilian truck, so you can easily swap on a civilian 5th wheel. I did this with one of mine (added a Fontaine slider), which lowered the 5th wheel plate height by around 8". Fortuitously, several of the holes lined up, so there was a minimum of drilling.
The significance of this height drop for me was taking my M129A4 trailer nose height from 13'9" down to 13'1". The TSS is a similar height.
The slider allows more clearance for the rear wheels on short-necked trailers. My M128 would snag the landing gear feet on the rear tires under certain conditions, like turning off a flat road into a gently sloping driveway. Fortunately, those feet are hinged and can be strapped up on the back of the legs when traveling, however sliding the 5th wheel back one notch would eliminate the problem.
Oddly, the short little M146 shows no tendency to rub the landing gear.

When shifting from forwards to reverse and back, always pause in neutral, don't zoom through. Personally, my shift pause is something like forward-neutral two three-reverse.
Never use reverse in low range! The manual tells you this, and some who have not heeded the advice have seen large expensive parts of the truck literally fall out underneath.

Cheers

thanks!, i didn't know about the wedges/tilt feature. that will actually come in very handy for some of the places on the farm that i would have to do a short haul with hay on through the river flats (about 7 miles). I suppose that the extra height could cause problems for non military trailers though if they aren't really designed for that much height on the tractor

 

[Trailboss]

The A1 model has the NHC250 (Cummins 855) engine. The A2 model has CTIS fittings visible on the wheels, and the turbocharged 8.3 Cummins engine.

If you're planning to haul commercial trailers over the road, be advised that the truck light system is 24 volts, not 12 volts.

 

[snowtrac nome]

an 85 should have the 855 with no ctis, if I were choosing a 5 ton that's the way I would go. Be advised the transfercases are kind of weak and wont stand up to trying to rock the truck or low range 6x6 that's why there is a placard that says not to reverse in low range.

 

[yotawheeler]

The A1 model has the NHC250 (Cummins 855) engine. The A2 model has CTIS fittings visible on the wheels, and the turbocharged 8.3 Cummins engine.

If you're planning to haul commercial trailers over the road, be advised that the truck light system is 24 volts, not 12 volts.

I should be able to just go through the trailer and replace the lights with 24V bulbs and be good to go though, correct? I know on a truck/power unit its not that simple to switch to 12V but the trailer should be pretty easy to change over right?

 

[Trailboss]

I'm not sure about the lights, but sounds like it should work. If you're only using commercial trailers, you'll have to change the plug to match the trailer socket. If you plan to also use military trailers, you could splice in the commercial plug and also keep the military plug, or get 2 cables and switch them out. The airlines and glad hands are the same on both types of trailers.

 

[fasttruck]

Memphis Equipment sells a converter to go from 24 military plug to 7 pin 12v commercial plug if you want to do both civilian and military trailers but it not real cheap. Check with them on price. In service we used to interchange trailers between M818s and commercial tractors. If you were trying to hook one with an 818, as long as you could get the end of the chassis under it you could scoop it up on the ramps behind the fifth wheel. If you were going to drop the trailer for a commercial tractor or M915 you left the landing legs 6" off the ground and let the trailer slide down the ramps. Care had to be exercised to make sure the truck was level left to right and you were on a hard stand.

 

[M813rc]

I should be able to just go through the trailer and replace the lights with 24V bulbs and be good to go though, correct?

Yes.

Cheers

 

[fasttruck]

Reference post 14: guess again. Military lights do not have any two pole sockets like a commercial trailer unless you have a M 872 or something that has dual 12/24volt capabilities. The military trailer line has no brake light circuit: the brake lights are actuated through the turn signal circuits. A commercial trailer has a separate wire for the brake lights. It will take more than changing the bulbs to make this work.

 

[fasttruck]

Reference post 15: civilian 12 volt trailers typically have a 2 post socket for the 1156 bulb that does the brake light or turn signal and as a running or tail light. The 24 volt bulbs used by the military hare are single post bulbs and the indexing pins will not match a 2 pin socket. The military 24 volt bulbs used in BO marker and service running light may fit (I haven't tried this) in the single pin circuits. Then there is the circuit issue as a M931 does not have a separate brake light circuit and the trailers do. M915s can do 12v commercial trailers or 24 volt military trailers so maybe a study of the circuit diagrams for a M m915, 916, or 920 may yield a solution.

 

[simp5782]

You can buy 4amp 24v to 12v step downs for around $15 each. You would need 3 of them. Scotlok splice into the tail light harness on the truck for your tail and turns. You would need a jump wire from the other side for the turn signal on the opposite side. You can then hook each wire for the lights thru the step down and mount up a connector right under the back of the bed for the trailer plug you wish to run. Each step down can handle about 5amps so led lights would work best on the trailer.


I have a 4 flat blade setup on my truck for my small trailer