My new LMTV is blowing water pumps and loosing alternator brackets!

[Aernan]

I find that Home Depot is hit or miss for the metric hardware for these trucks, but Ace Hardware seems to have a much larger selection (stainless, 10.9/12.9 class fasteners, flanged head, various lengths, etc.).

I haven't been to an Ace in years. I would have never thought of looking there. Thanks. I'll pop in. I'd like to get some of the basic 6mm bolts that appear all over the engine for spares so I can swap the rusty old ones out as time permits.

 

[Awesomeness]

If you're going to get a bunch, I would order from McMaster or Fastenal. Ace is great when you need a few, but they only have them stored in little divided plastic organizers so they only have a few of each type/size.

 

[Aernan]

If you're going to get a bunch, I would order from McMaster or Fastenal. Ace is great when you need a few, but they only have them stored in little divided plastic organizers so they only have a few of each type/size.

That's sound advice. The next trick is figuring out what the common bolts/nuts are on the vehicle so I know what to order.

 

[Awesomeness]

What I do is any time I need a bolt (and can wait to get it) I order a whole box from McMaster. I usually wait until I have a few different bolts to order, to save shipping. I keep them organized by diameter in a plastic parts organizer (e.g. M4, M6, M8, etc.). I only have a couple lengths of each size, and some have an extra head type or two (e.g. flat head, socket head cap screw, pan head, etc.), and it seems like I'm buying them less often because I already have them. You'll see in my parts spreadsheet that I list any (most anyway) bolts I've bought. The parts TM lists out many of the bolts too (e.g. "Bolt, M8 x 40mm", etc.). I've been buying stainless bolts for non-structural things (e.g. for dash bolts, but not for the water pump). I still go to Ace a lot though too, when I know I just need a couple and probably won't need more anytime soon.

 

[Duckworthe]

Good morning all. So I posted a few pages back that I had my bracket issue fixed. Well it was for about 3000 miles. I was just out in the mountains near Idlewild Ca and I noticed that my belts were loose. I looked at the mount that I had built and noticed that it had broken the welds. all the bolts were still tight but the ear of the bracket broke off. I haven't had a weld break in over 40 years. Everything else was fine luckily. I think I am going to sit down and see about a better system for this mount. Probably just mill it out of a single piece and see if it can be double shear also. This is obviously a serious problem that many of us are having. It should have more than a single top ear supporting it. Maybe one in the top rear also. I will let you all know what I come up with as soon as I can. I need to be on the road soon so I need to get busy! For now, I'm glad I carried a small ratchet strap. Have a great day!

 

[Awesomeness]

Stronger brackets are great, but I think that is trying to treat the symptoms not the root cause. Without solving the underlying issue, if you eventually build a bracket strong enough not to break all you will likely do is push the failure to the next weakest part in the chain. I doubt it's "just an LMTV poor design problem" or it would be much more prevalent. Enough of us have the similar issue that we probably found an root cause we have in common - my bet is still on drive shafts.

 

[coachgeo]

Good morning all. So I posted a few pages back that I had my bracket issue fixed. Well it was for about 3000 miles. I was just out in the mountains near Idlewild Ca and I noticed that my belts were loose. I looked at the mount that I had built and noticed that it had broken the welds. all the bolts were still tight but the ear of the bracket broke off. I haven't had a weld break in over 40 years. Everything else was fine luckily. I think I am going to sit down and see about a better system for this mount. Probably just mill it out of a single piece and see if it can be double shear also. This is obviously a serious problem that many of us are having. It should have more than a single top ear supporting it. Maybe one in the top rear also. I will let you all know what I come up with as soon as I can. I need to be on the road soon so I need to get busy! For now, I'm glad I carried a small ratchet strap. Have a great day!

Do I recall right that your Camper Module is direct bolted to the chassis? If so could one unintended benefit of the front spring mounts on the 1079 system that it reduces other stresses that flow thru the system? Granted the Alt. Bracket etc would certainly be a very indirect relationship to the mounts so it is a bit of a stretch (pun not intended) The Beds are direct mount too but they are lighter...... sure they get loaded...... but not "all the time" like a camper module.

Or is that someone else's rig that got direct bolted?

 

[Recce01]

Do I recall right that your Camper Module is direct bolted to the chassis? If so could one unintended benefit of the front spring mounts on the 1079 system that it reduces other stresses that flow thru the system? Granted the Alt. Bracket etc would certainly be a very indirect relationship to the mounts so it is a bit of a stretch (pun not intended) The Beds are direct mount too but they are lighter...... sure they get loaded...... but not "all the time" like a camper module.

Or is that someone else's rig that got direct bolted?

i might be wrong, but I think Eric's camper is lighter than the standard bed? I am watching this thread closely. I hope you guys find the root issue!

 

[Awesomeness]

Officially declaring it a root cause will be difficult, because the cause-effect relationship is so indirect.

My front driveshaft had 0.055" runout, which is way more than the 0.005" spec. It was also out of balance, one spline twisted ("out of phase"), and the u-joints had wallowed out the ears of the yoke so that the u-joint caps were no longer a press fit and were instead slip fit. I had all that fixed in one shot. So if it was the driveshaft that broke all my stuff (e.g. water pump, alternator bracket, cracked block), I don't know if all those issues with it were the sum contribution, or if any one of them happened first and then caused the others. Also, the best I'll know is that if it doesn't happen again the driveshaft could have been the cause (a lot of other things have changed too, such as new bolts and Loctite on everything, so we're not following the scientific method of changing one thing at a time).

I haven't checked the front shaft.

One thing that I like about blaming the driveshaft(s) is that other issues would not have damaged the driveshaft, but the driveshaft could have damaged other things. For example, if the transmission was having some kind of shifting issues it is unlikely that it would have bent the driveshaft or knocked it out of balance.

 

[Duckworthe]

My camper is directly mounted as the bed was. Yes, my camper weighs less then the bed system did on the truck. I am going to take my shafts down to my drive line shop and have them checked out anyway, and that will give me a reason to look at the u joints at the same time. Who knows, it might be one of the reasons Uncle Sam started getting rid of these older trucks in the first place. we always follow the methods of "Get 3 bids to build trucks, take lowest bid, wonder why truck is not the best thing on the planet, get 3 new bids, take new truck and wonder why its not the best truck on the planet, rinse and repeat." well you get the picture. Anyway, I love my truck and will keep using it as I built it to be used. If I have to repair things as I go, so be it. My truck hasn't been in the shop as often as my other diesel pushers have been. When that happens I will retire it also.

 

[Awesomeness]

will give me a reason to look at the u joints at the same time.

Another thing I forgot to mention is that all the safety/lock plates on my u-joints were missing! There are supposed to be these thin sheetmetal plates that you put on top of the u-joint cap before the bolts go in. After the bolts are in, you bend up the ears/tabs on the sheetmetal and it hold the bolts so they can't vibrate loose. The torque spec on the u-joint caps is surprisingly low (like 20 ft*lb; it's in the manual), so those safety plates are doing all the retention. I'm not sure if you can buy them from somewhere else, separately, but my new u-joints came with them.

 

[coachgeo]

My camper is directly mounted as the bed was. Yes, my camper weighs less then the bed system did on the truck....

About how much is the Bed System's Weight? What all do you include in your term "Bed System" (just so not too assume). Do you perchance got a clue on what the Box on the 1079 weighed? Was ir aluminum and steel construct?

Now that I think about it... this will hijack this thread. Feel free to PM so not to hijack this. Or throw it up in your thread on your truck. Look forward to your report on what your shafts come out as. I am for sure going to the first 6x6 axle as my single rear axle.

 

[Aernan]

Just discovered there was a driveline update. If you look on your data plate there should be a giant D stamped in if it was done. I was told they changed the drive shafts and steering components.

 

[frank8003]

Just things I see lying around
View attachment LMTV ADA416765.pdf

View attachment LMTV story.pdf

View attachment LMTV problems and industry 11132017.docx

 

[Awesomeness]

Just discovered there was a driveline update. If you look on your data plate there should be a giant D stamped in if it was done. I was told they changed the drive shafts and steering components.

Interesting. Do you have any more information (a document perhaps describing the install)? Do you have a picture of a data plate with the "D" stamp?

 

[frank8003]

see post #20 in here.......................
https://www.steelsoldiers.com/showt...-early-years-before-1996-first-contracts-quot

 

[Awesomeness]

Just things I see lying around
View attachment 708089

View attachment 708090

View attachment 708091

Interesting. It sounds like all the trucks should have received the upgrades - I wonder if that's true. It's also clear that when things aren't right in the driveline, it can have big effects.

As an aside, I wonder what this looks like? "One of Mitchell's suggestions — a reinforced rear tail light assembly that can be used by soldiers as a foothold to climb up into the cargo area at the rear of the truck — will be implemented."

 

[scottmandu]

I think I am going to sit down and see about a better system for this mount. Probably just mill it out of a single piece and see if it can be double shear also.

Stronger brackets may certainly fix the bracket breakage problem, but that will move the failure to the next weakest link. An engine block is far more difficult to repair..

 

[coachgeo]

Just discovered there was a driveline update. If you look on your data plate there should be a giant D stamped in if it was done. I was told they changed the drive shafts and steering components.

They ALL got the update long ago. Been discussed in here previously a good bit. Either that study... or a second study done later. ( I forget which) made a recommendation based on solid analysis to use a special type of CV jointed driveshaft . They did NOT take the recommendation and went/stayed a beefier drive line as mentioned in above info. Think they also updated TM's (in 1998 and put increase eye on the issue with more often maintenance and stricter tolerances on when replacement of driveshaft must be made. Then in 2008? they started making all new LMTV 4x4's with a different rear axle "sorta". Sorta as in.. started using the front 6x6 axle in the 4x4's. This raised the rear driveshaft to something nearly parallel to the chassis which allows for small vibrations to have less effect on things up the chain.

Post 76 just above points to more info on the topic. A search will find you even more detail on this topic as well.

 

[Awesomeness]

Either that study... or a second study done later.

It looks like that is the later (2003) study. Here's the first one (1998 ).

Check this out...

The first failure on this vehicle occurred the second day of actual testing. The vehicle's water pump cracked and started leaking coolant. Testing was stopped with 80.3 miles on the vehicle. The water pump was found to have a 5 Vi inch crack starting across the top and moving down the side (see figure 3). The location of the crack indicates that vibration in the vertical direction is the most likely cause.

It is our opinion that some redesign of the bracketry holding up the alternator would likely reduce cracking of the water pump. The water pump is bolted to the engine on the left side (referring to figure 3). Bolted onto the right side of the water pump is the bracketry used to hold up the alternator. The weight of the alternator and its associated bracketry is just over 60 pounds. This weight is supported by a combination of the water pump and a straight bracket off the engine which is in turn attached to the U-bracket. However, do to the configuration of this bracketry (see figure 4), the water pump ends up supporting a good portion of this weight.

That doesn't sound like the exact bracket we currently have, so I'm assuming they changed it as a result of this study. Interesting how their first failure was the water pump. Next the starter cracks (like mine did). Then a u-joint seizes.

View attachment ADA366822 - LMTV Driveline Failures.pdf

As an aside, for the money the government spent on this report, it's as if nobody proofread it before they submitted it as official. I would be ashamed to turn this in.