M923A1 30,000mile OTR Report

Ok gents as most of you know I do transport a lot of equipment and trucks crisscrossing the southeast and middle part of the US in my 923. I hit the 30,000 mile mark yesterday when I crossed into Illinois. I started doing this with around 180hours on the engine meter around july 1st. It now reads a little over 1000. All miles are GPS calculated for record in my log book. The hours vary due to warm ups/dead idle/and just general running time. My NHC250 has some mods done to it as you all know. My standard empty gross weight for truck and trailer is 38,780lbs. 923 weighs 27,460 with two full tanks and me in it. and the trailer weighs 11,320lbs empty with all its chains and crap. Max gross weight on all of my hauling was 72k. I generally gross 52 to 58k with any load.

Lets start with repairs made during this time.

-Radiator replacement - Small leaks in the core. I believe from an nose to nose impact with an LMTV having to be jerked off the trailer. Replaced with a used one. I went in and replaced all the hoses and clamps along with the thermostat at this time to get it over with.
-Heater core- Lets face it. It is getting cold and mine leaked from day one.
-Small brake lines breaking I guess due to vibration.
- Transmission replacement - Burned up in November. Unsure why. Replaced cooler as well.
- Replaced Tie rod ends - They were just flat worn out.
- Replaced shocks - Tire cupping
- Replaced lowest leaf in rear springs on both sides. They were both broken.
- Replaced RR lower dogbone bracket clamp. Came up missing. Bolts missing. Assume vibration caused this.
- Replaced All air diaphragms as I had a massive air loss on stopping. Also replaced the shut off valves for the primary and secondary tanks.
- Replaced two tires due to wear/blowout on 1.
- Replaced 1 fuel filter along with several oil changes. Spin on Donalson filters, Rotella 15-40. 175hours/7500miles per change.
- Replaced 3 spring brake can tubes. I have had several break off. This is my current major problem as I have broken 4 so far. Even the brackets have broken.
-Replaced water pump and belt due to broken plastic impeller.

My injection pump, dual fuel line kit, ram air system was all done prior to starting all of this hauling. Along with my belts and u joints. I also grease the truck every 100 hours regardless of the miles.

Fuel mileage is calculated in different ways. Loaded 50-62k in weight is approx. 5.6mpg. This mileage can go up and down as well. I get around .5mpg more with a skid steer in the bed of the truck over it being on the trailer that weight I guess helps a lot.. At 72k I got around 4.8mpg. With an empty trailer I am seeing consistent usage of 37 gallons of diesel over the 303 miles from my place to the pickup yard in Texarkana. So around 8 mpg. No traffic all highway non stop 5 hours of driving.
With just an empty truck I am unsure on the mileage since I hardly ever am with just the truck itself. My speed varies but I tend to cruise at around 2050/2100rpms around 59/61mph. give or take how many hills there are.

I have specific places I tend to fuel up at along my travels. I shop around for diesel and avoid truck stops due to the high prices. I tend to stick to Kroger, Murphys/Walmart, and BP fuel. I will force my way into a Kroger for the 3 cents off $2.13 a gallon over the $2.57 a gallon at Loves. It is even $2.73 a gallon at Loves near Paducah, KY. Best mileage I have gotten off diesel was from a BP in Montgomery, Missouri. Worst mileage is from Loves/Pilot stores. I also get better mileage and it seems a lot more power running after 10pm until about 9am. Just seems to run better and is quieter.

I did notice the in-cab temp started to get a little cold at 15 degrees outside temp running 60mph. I need to do some sealing on the windows.

I will post some pics of repairs I have made and what not tomorrow as well as my fuel filter change. This one has alot of miles on it.

Outstanding write up!

Very nice write up, this kind of thing fascinates me as someone who's considering not only daily driving a 923 or 925 but also driving cross-country with one visiting most if not all states. Keep us posted on how things progress.

I'm really glad you did this Simp. It gives us a vague glimpse into the future of the life of our own trucks, in a much shorter period of time. Be sure to keep us updated as time permits. Stay safe in your travels.

Very nice write up Wes. Is shows these truck need to be worked to stay fit. Sitting long periods and little to no use really affects their reliabilty. Once the bugs are out , they keep rolling.
JC

Excellent information documented!!

I would like to suggest you look for farmers coops along the way for diesel. They have premium diesel at good prices most of the time.

Fuel filter was replaced 7/12/16. Approx 5,500 gallons of diesel ran thru it. Kinda nasty as well as the can. Did have a small clean spot. I tore the cardboard cover off.

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Here again, this is fascinating, Wes! I'm an eventually to be M923A0 owner, and I intend on driving it that much myself, so seeing these well-used (they usually weren't by the military) is interesting to me...what will need repair/replace and after how many miles, etc.

Had a blowout on the way back from Hattiesburg on the drivers front tandem. It always something. Air impact gun didnt want to work right. Trigger is messed up. Then couldn't find my manual socket. Found the bar but not the much needed part. Also did not have my trailer with me so i did not have a chain to bind it up with. Ended up using a big ratchet strap and limped it the 4 miles to Loves to use their impact. About a 3hr delay total. Did not have any rim damage this time. When i blew out the last XZL it did some wheel damage and tore some stuff up.

That tire was one of the last originals i started with so it was around 36,000 miles. And nearly bald. I had to plug i a few weeks ago so it was on its last leg anyways. Hoping to come cross some 14.00 xzl's on the tire contract.

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Update at 60,000 miles on 6/9/2017

OK folks cross the 60k mark yesterday since July of last year. Was a long week. Did 2,700 miles this past week alone. Not too many problems to note in the past 30,000 miles. Or atleast anything major. I just changed my oil again and found some pieces in the bucket when I was done. Nothing to be concerned with I don't think. Just looks like some slag. I had a drain plug that the magnet has gotten week so I replaced it. No telling how long it might have been in there. This is only my second oil change in 30k. The last oil change had 43% life left when I changed it at 15,000miles. I am going to have this oil change lab tested as well. Replaced my fuel filter again. I haven't since the last report and this one looks about the same but didn't appear to be too bad at all. Also some pictures of the filter canister. Some dirty water at the bottom but not bad considering I NEVER drain it. Had 2 blowouts this go around on the new 395s. Probably due to road debris or road conditions with the massive craters. I am still on the original Napa fan belts. I have replaced the alternator and PS pump belts since I had to get longer ones.

Repairs are as follows.

-3 torque rod inserts broken and replaced with some stock and some of the HD versions.
-Replaced Air Filter
-Oil changes x 2
-Air Compressor - Most have read the thread on that. Also replaced some air lines.
-Air Dryer - Caused by compressor
-Installed an Updated alternator how ever the alternator quit charging due to overheating. Problem was solved.
-Water pump belt broke x 1. Bad belt I guess.
-Double Check valve # 7 was replaced after it failed.
-Transfer case replaced after the oil pump went out in it.
-Both lower leaf on the spring packs are breaking... again....
-Both turn signals in the front quit working. One turn wire had broken near the hole where the harness comes thru the frame, the other was a bad pin in the switch so I jumped the harness to one of the two wires going to the rear turns.
-Updated the 24v Flasher Relay for LEDs
-Upgraded to 8D batteries, Ran dedicated charging wire.
- Replaced window channel runs and 1 regulator.
- Broke the downpipe at the engine flange - Welded new flange on
- Replaced Power steering lines - Just old and some leaking
- Replace Steering shaft joints - Just flat worn out.
- Dropped the button in my pump to a #18 and did an inspection about 10,000miles ago and everything was looking good.
- Swapped to 395 XZLs on LMTV wheels with runflats
- Replaced RPM cable - Air discharge line burned thru it.
- Some wiring issues due to pinching or just bad connections.
- Replaced Air governor - Was not letting the compressor cycle off.

I added air conditioning, LED marker, backup and front lamps to the truck, Did the parking light mod with the front turn signals, Redesigned the air intake system I use, Tinted the windows, Added a Puradyn Oil Bypass Filter system, added 16 inch fans again to the front.

Yes my front turn signal lights are painted black but you can see the turn signals thru them during the day time and at night they are still pretty bright.
It is just a slight black layer so I don't have the big orange on the front.

Mileage with 395s went down some as expected especially with run flats installed. On a normal day to RRAD - 313miles there empty at 38,200lbs returning with an SEE the 313 miles which is around 16,000lbs added burns 116 gallons of diesel. so around 5.4mpg. On a recent trip with just the truck I didn't calculate mileage really but I went Memphis to Raleigh, NC on my one drivers side tank.

I run Donaldson Fuel filters since they cost around $30. I run a Baldwin B96SS Severe Service Oil filter. Or a LuberFiner670XL if they have it. Handy that the same filter for the Transmission works for the engine. So I just buy a bunch of them. I run Rotella 15-40 standard stuff and buy it at wally world. I do add a gallon of Lucas to it though as well. It helps I believe. I also add the Lucas fuel treatment to the tanks sometimes but not a lot of the time. I didn't notice any difference and the pump seems to be ok with it.

Turn and parking

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Thanks for the "LEAD THE FLEET " (LTF) evaluations Simp, I don't think I will ever reach 60 k, I am just over 4k, biggest thing plaguing mine is NOT ENOUGH DRIVING, sitting alot

Thank God you have that air ride seat in there or you would spend just as much on preparation H as you do diesel

Well here is a brief 80,000 mile report, Since I did the big 16 speed swap. I have done a few long road trips.

Broken items between 60k and 80k :
- 2nd Allison Transmission
- 2nd fan clutch - Rear bearing failure
- Front main seal is leaking
- Replaced all the belts after 1 broke, This set had been on the whole mileage I have driven.
- 1 torque rod bushing that I just replaced for the heck of It since I had it apart.
- Replaced the broken rear leaf spring pack with a set of wrecker springs
- Check Valve at the primary tank
- Swapped both Rear ABS modules with NON ABS valves
- Air filter
- Air compressor discharge line collapsed and I replaced it.

Went in today and inspected the front wheel bearings and brakes. I have not had them off since I got the truck in June 2015. Everything looked good inside.

I plan on running the overhead on the engine sometime this week and replacing the front main seal. I also will replace my water pump belt while I am in there since it is loose again. The eccentric does not seem to work properly.

https://youtu.be/J8pexFi36XU

Simp , Your reports are invaluable , Thank you, they are very insight full . Couple of questions,

1. The primary tank check valve, did you change it because you had air venting up the Intake

and

2. did you run ATF in your trannys before failure ? not HYD OIL , do you think your failures are lack of cooling ?

Iam not pounding the miles on like you but my main failures have been , The Air dryer check valve, replaced air dryer ASSY with a MRAP item, seems to really take care of the moisture I had before . Bad coolant shuttle valve and various brake system valves, most of which I found P/N s for because you took the time to pass them 0n. In the AIr Force Aircraft or Jet Engines that are used to amass hours ahead of the fleet to find weak links are called Lead The Fleet "LTF" You certainly are Lead The Fleet Thanks, Andy

Jericho said:

Simp , Your reports are invaluable , Thank you, they are very insight full . Couple of questions,

1. The primary tank check valve, did you change it because you had air venting up the Intake

and

2. did you run ATF in your trannys before failure ? not HYD OIL , do you think your failures are lack of cooling ?

Iam not pounding the miles on like you but my main failures have been , The Air dryer check valve, replaced air dryer ASSY with a MRAP item, seems to really take care of the moisture I had before . Bad coolant shuttle valve and various brake system valves, most of which I found P/N s for because you took the time to pass them 0n. In the AIr Force Aircraft or Jet Engines that are used to amass hours ahead of the fleet to find weak links are called Lead The Fleet "LTF" You certainly are Lead The Fleet Thanks, Andy

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My First Allison went out due to heat. I know that. It had Dextron in it. The second one I went thru it before install and put dextron in it as well. It ended up having a rear output bushing go bad and caused a vibration which backed the bellhousing bolts out of it and eventually pulled the torque converter out of it. It pretty much burned it up.

Heat was what I noticed on the transmission the most. June towing up and down hills the truck temp 210 and the trans temp 225/240. When I went over to the MRAP radiator which has the built in cooler and I ran the Allison cooler lines to it and bypassed the heat exchanger the trans temp would never get above 160 even on long pulling hills. So almost an 80 degree drop on that alone. I was amazed at that. Profo runs the same setup in his big camper and his temp is a steady 160 as well.


The check valve is that KN23000 one way valve. Mine was sticking and wouldn't allow air to build past 60. it was weird to track down but that was the culprit. I guess it was closing and then the secondary tank wouldn't bleed over air either. It was actually a nightmare to track down. Ask people who talked to me on the phone. Flipping out crazy trying to find that little issue.

It would build with the shop compressor on it to 145 but with the truck compressor at idle it didn't have enough CFM to force it open I guess unless I was up around 1800rpms

How are you liking the wrecker spring setup?


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Hey Wes,

Great log, thank you but you never mentioned if you added any trans fluid in your diesel or did you run it straight? Any injector issues with them sticking?

Thanks again...

Jbulach said:

How are you liking the wrecker spring setup?


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Not as bad empty as one would think. With a load in the bed and behind it she just floats. It's pretty nice. No broken ones yet.

Thanks for the speedy reply, I watch you post constantly Andy