LMTV Alternator Disaster, engine now catastophic

[Aernan]

I don't have high hopes in improving the fuel economy of the truck but I do hope that I can find lower cost fuel sources to augment the diesel. I'm hoping that methanol/water can help. Diesel is currently $3.50-$3.80 a gallon in San Jose CA.

 

[snowtrac nome]

the c series is longer and taller than a b, it will make a bit more torque, and is a wet sleeved engine not a bored cylinder like the b series and 3116 cat. the cat is a 7 liter engine and the c series engine is 8 liters. the c series should be about the same size as the cat but a b will be much smaller.

 

[aleigh]

Another version of all this, of course, is for the money I just double down and buy another LMTV. Make a good truck out of the pair, pallet the extra Allison and axles for a rainy day, pick it over for good parts, and scrap the chassis. My one with the bad engine is in phenomenal condition otherwise.

 

[mkcoen]

Another version of all this, of course, is for the money I just double down and buy another LMTV. Make a good truck out of the pair, pallet the extra Allison and axles for a rainy day, pick it over for good parts, and scrap the chassis. My one with the bad engine is in phenomenal condition otherwise.

That sounds like the less stress version.

 

[aleigh]

Maybe I need to do a poll, haha.

A) reman / new engine
B) 2nd LMTV
C) swap (6CTA/etc)

 

[snowtrac nome]

I was once a diehard cummins fan, since I have spent the last 10 years on cat stuff, I cant say its any better just a little different. I wouldn't go through the trouble to re power unless I had an engine I could no longer get parts or service for. Like I said I have a snow cat wit a dorset ford diesel in it I replaced it withy a like motor because I believe that was the most cost effective way to do it.

 

[coachgeo]

well.. IMHO:

. the commercial version went with a cummins for a reason.... it fit the needs of the kind of use it would get.... and better matches the needs of what most of us need too.
. The needs of the military version was fit better with the CAT 3116.

So now if you keep that in mind.......

. as the military jumped up to a newer CAT as it became available......
. if they had kept the commercial version going it too would most likely jumped up an engine as well..... aka jumped up a Cummins 8.3 or to the 24valve

Since 24valve is electronic? and would complicate things... IMHO go 8.3 to keep in line with the progressive step it would have gone to anyway ...

 

[aleigh]

I'm telling myself on the bright side that at least with all this I can try to solve A/C at the same time. I have one of the HVAC pods sitting here for the cab, with the A/C.

 

[Duckworthe]

I do engine swaps a lot in my world and I can safely say this, "It always seems like a great idea at the start. Then after you get it bolted into place, (which it the easy part), You have to start getting into all of the little things that take a tremendous amount of time to get finished. And it also can start diving deep into the Wallet, $$! Most people cant finish a hotrod build let alone a project of this Physical size. Many on here including myself make this stuff look easy, "Heck, I will just make this bracket to replace the correct one that wont fit!" But many on the our site, and many I have met in person, just don't understand the amount of work and money it takes to swap any type of engine. That's why you can find a million unfinished projects for sale everyday. Not to mention that life just gets in the way sometimes. Just to be clear, Aleigh, this is not pointing directly at you! Heck you might just be the person who pulls this swap off! I would just do the direct swap if I had the known good replacement engine in my possession. I look at the cost of the engine swap and the vehicle it is going into. I hate to do it but many of my friends have purchased a several thousand dollar LS engines to put in a car that will never be worth a grand in the end except for parts. But to each his own and sometimes we do things just because it doesn't make sense!!! LOL good luck and sorry to hear about all the trials! Eric

 

[Aernan]

Update: Had new drive shafts fabricated and fitted. Have done a few hours of freeway driving on them now. The truck is no longer shaking violently and is actually becoming nice to drive. No longer losing the alternator bolt. Have checked it recently it's still on and tight.

 

[aleigh]

Update: Had new drive shafts fabricated and fitted. Have done a few hours of freeway driving on them now. The truck is no longer shaking violently and is actually becoming nice to drive. No longer losing the alternator bolt. Have checked it recently it's still on and tight.

It was shaking violently? Yikes. My truck is (was?) nice and smooth.

 

[f8617]

I'm currently getting over 8 Mpg out of my truck but it's unloaded. Rumor has it you can get 10 out of the truck with tuning, tires, high speed gears...

One of the sources in that study (post #213) cited significant rolling resistance losses due to under inflated tires. Perhaps LMTV/FMTV's 55psi maximum CTIS pressure should be closer to the 95psi maximum tire pressure?

 

[coachgeo]

.... My truck is (was?) nice and smooth.

Have you had a chance yet to see where the oil came from? Hopefully it is one of those hoses mentioned. (turbo return or the other one that rubs) Twould be nice to not need a new engine.

 

[Pointman0853]

Again, I crawled under mine yesterday to check the rear prop-shaft. I found play in the splines and a pooched rear u-joint. My A-0 truck has had the 'D' mod redone and the current prop shaft is definitely the 4" unit. I just snowed here...finally, so I plan to pull the prop shaft and have it re-balanced. New U joints front and rear, and it should be good to go. Any remaining vibrations would most likely come from shimming the hubs..

I have already replaced the front prop-shaft with one from an A-1 and it calmed things down quite a bit.

There are reasons the Gov. are selling these trucks. I would love to to see the repair sheet on what was needed to repair each one before the decision was made to get rid of them. Something to think about, as we all trouble shoot and chase gremlins that seem to be mostly maintenance items...

Pointman

 

[aleigh]

So just an update on this. What a long crazy road it's been. With some distractions like buying a business and lining up a replacement engine, the truck is up at Zender's Diesel in Bellingham WA right now getting the new engine in. The old one's out on the ground, and they are thinking this week maybe. I am kind of glad it took this long in a way because now I don't have to drive the truck down to AZ in 120 degree weather.

The old engine had 4 bearings spun and was good and seized. Apparently caused them a bit of a problem getting it out because the T/C is snapring'd onto the Allison in this application so they couldn't just slide them apart. Someone else must take an LMTV in there, they just said they had another in recently that the guy had done the ATF conversion on for the tranny. I'm also having them have the driveshafts spin balanced and replacing all the u-joints, for peace of mind more than anything else. I'm still convinced that overheating cooked the engine and the rest was just inevitable.

Now we wait to find out if that engine I lined up for it is good!

Any tips on what to scavange off the old engine before I junk it? I'm thinking about picking up the turbo, air compressor, etc.

 

[wheelspinner]

Any tips on what to scavange off the old engine before I junk it? I'm thinking about picking up the turbo, air compressor, etc.

Injectors, hydraulic pump, any bracket, hard lines that carry fluids ( a lot of them will fail eventually from vibration). That's a good start anyways

 

[aleigh]

I guess the TPS for the Allison too now that I think about it

 

[olly hondro]

This thread freaked me out when I read it, so I asked Jack to make sure the alternator bolts are tight and should I get the drive lines balanced? His reply:

"The factory fixed the vibration problem years ago, they put all new drive lines on and changed the flywheel housing on the first batch of LMTVs, the Military wasn't allowed to drive them over 35 mph until that was fixed."

I'm ok with that.

 

[Suprman]

Things still vibrate loose or become unbalanced on 20 year old trucks that have been put thru the ringer though.

 

[olly hondro]

I agree, Supr, it looks like the first two items in the LMTV tool kit will be locktite and torquewrench.