LMTV Alternator Disaster, engine now catastophic

[Aernan]

That MHC is killer. I think I got to get one now.

 

[Aernan]

So while on youtube I got a targeted advertisement for a tool that uses a laser to analyze vibration in motors and drivelines. http://www.fixturlaser.com/Shaft-Alignment/Fixturlaser-SMC/
I have no idea how expensive it is but it sounds awesome!

 

[scottmandu]

I'd suspect just a few LMTV's worth is what it costs.

 

[Aernan]

More on vibration analysis. There is an iPhone / Android app for $400 that does full driveline analysis.

Sent from my SAMSUNG-SM-G930A using Tapatalk

 

[DiverDarrell]

Or just check your drive shafts. My truck started random shaking, found the rear shaft has .02 movement. Probably more but too lazy to set my indicators up for a more precise test when I already know it’s bad. Wheel balancing can be done with airsoft pellets in the wheels. I found with the rim locks in that there is no way for them to get into the ctis.

 

[Aernan]

Or just check your drive shafts. My truck started random shaking, found the rear shaft has .02 movement. Probably more but too lazy to set my indicators up for a more precise test when I already know it’s bad. Wheel balancing can be done with airsoft pellets in the wheels. I found with the rim locks in that there is no way for them to get into the ctis.

Tell me more about this wheel balancing using airsoft bbs

 

[Awesomeness]

Tell me more about this wheel balancing using airsoft bbs

Not much to it. You open up the tire, and put a bunch of airsoft pellets or ball bearings in. I think the number thrown around is 1oz of pellets for every 13lb of tire, which means if you use airsoft pellets you need a lot of them (1/2 gallon?).

 

[DiverDarrell]

Here is my write up

https://www.steelsoldiers.com/showthread.php?159554-FMTV-LMTV-Tire-balancing

 

[aleigh]

Remember that time I drove up to Seattle for Christmas, missed christmas, and then stayed for a month...

Picked up the radiator, fan etc from Will yesterday at UPS. Going to give it a go this weekend if all goes according to plan.

 

[DiverDarrell]

Well at least you got to see some rain you were missing out on.

 

[aleigh]

Got the air clutch replaced. The holes were not lined up with the bolts on the old one, so bodged up an air supply and it came loose after I hit it with a hammer a few times, thankfully. Wonder how you get one of those off if the clutch is busted and won't release. The water pump gave me a start when the replacement had an extra hose takeoff, but a 1" expansion plug from the local parts store fixed that. Couldn't find cat yellow in a hurry so just painted it tan. I claim it's a tactical water pump now.

The holes on the bracket were still bodged up from all the problems, but welding solves everything right. I didn't see a reason to need to remove it again (or if I do I'll just get a new bracket). That fourth stud/nut deal that bolts it into the water pump is a hateful thing. I got it by taking the water pump off but I wonder how people get to it with everything still on/in the truck.

The engine is great to work on when you can just stand where the radiator goes...
More photos: https://www.flickr.com/photos/adventioneering/albums/72157691979335674

 

[Awesomeness]

Got the air clutch replaced. The holes were not lined up with the bolts on the old one, so bodged up an air supply and it came loose after I hit it with a hammer a few times, thankfully. Wonder how you get one of those off if the clutch is busted and won't release.

Mine was exactly that, frozen and broke. What I did was hit it with a hammer to break it free, and then I used a large/thick screwdriver to reach in the hole and pry against the head of the screw in order to rotate the clutch housing until the bolts lined up with the holes. It worked way better than I expected it to.

That fourth stud/nut deal that bolts it into the water pump is a hateful thing. I got it by taking the water pump off but I wonder how people get to it with everything still on/in the truck.

Yeah, that 4th nut is not ideal, but I've removed it and reinstalled it several times and it's not that bad. There is a path up from below and behind that you can reach in with a wrench, and install it in 1/8 turns.

 

[Reworked LMTV]

I carry loctite around like women carry tubes of lipstick in their purses.

The thing I am trying to grok here is how the suggestion to use a pair of shorter bolts would work like he was suggesting. Since it has to go through.

Sometimes it is best to accidently swap LOCTITE for lipstick!!

 

[aleigh]

So earlier on this thread there was a big debate about my failures, people talking about bolts coming loose, vibrations, all that. I examined the old water pump closely and it failed by cracking on the front cover plate (A $40 part). This is more evidence towards my original theory that the pump was damaged after the engine over-heated due to dropping the belt. I sincerely hope nothing else is wrong, although it did make it hundreds more miles.

Also it turns out that if you put your NEW water pump on the tire and it falls off and hits the axle, right on the cover, it ruins the cover (goughed it exactly on the o-ring groove). This entire trip is cursed. I'm going to go pickup a new cover tomorrow (which is how I know they are fourtey bucks). There are two versions of the cover, one with a hole, one without. The LMTV takes the version without the hole. The part is cat #107-7701.

Also the replacement water pump I bought didn't actually FIT in the engine. Remember the extra hose take-off I put a freeze plug in? It turns out that hits on the engine. We ground it off short (like the pump I took off) and tapped in another freeze plug.

 

[Aernan]

Another data point. I lost my alternator bolt twice and my water pump was replaced before I got the truck (still unpainted). I checked my drive shafts for play and was able to shake them. I took them in for rebuild. The splines were trash, the main tube was bent and the u-joints were too work to be reused. So the shop made fresh drive shafts and fitted them. I wish I had known they were in such bad shape I would have ordered NOS or found aftermarket reinforced ones. The truck drives a little better but I believe I have a tire that is very imbalanced so it's still a bumpy ride.

 

[Awesomeness]

So earlier on this thread there was a big debate about my failures, people talking about bolts coming loose, vibrations, all that. I examined the old water pump closely and it failed by cracking on the front cover plate (A $40 part). This is more evidence towards my original theory that the pump was damaged after the engine over-heated due to dropping the belt.

You have the exact pattern of symptoms, including cracking the water pump housing, as the military studies and other posters (including myself). You ultimately won't know until you get the driveshafts checked, or break more stuff, but the logic favors you having the same vibration problems, not a different one. Those are just odds, so it isn't impossible, though.

Thanks for the note about the water pump not having the hole. I had both in my spreadsheet, and have removed the version with hole.

 

[aleigh]

The housing didn't crack. The cover cracked. To be pedantic, but I think it matters for the purpose of this discussion. The cover it turns out is CNC aluminium and the housing is made out of something else, some kind of steel or iron. It's not outside my imagination that they have different expansion characteristics and when overheated...

Also I don't know that correlation is causation - Maybe the knuckle head kids overheat the trucks a lot.

 

[Awesomeness]

The housing didn't crack. The cover cracked.

My "cover" is what cracked. We're talking about the same thing. I replaced the cover (which I have been calling housing to differentiate between it and non-waterpump parts like hoses and fittings), and then broke a bunch more stuff after that.

Also, if you are convinced it's steam pressure that did it, check your radiator cap. It should have released at a fairly low pressure to prevent just such things. (This theory really doesn't make a lot of sense objectively, since pretty much everything else should have blown out before the metal water pump cover... hoses, radiator passageways, seals, etc.)

 

[aleigh]

And you think this static part cracked because it was shook? I'm scratching my head at that one. Why that and not the oil pan, valve cover gasket, or innumerable other static parts also bolted to the same engine.

 

[Awesomeness]

And you think this static part cracked because it was shook? I'm scratching my head at that one. Why that and not the oil pan, valve cover gasket, or innumerable other static parts also bolted to the same engine.

The military studies answered that question in depth, with pictures, when theirs cracked exactly like that after something like 80 miles into their test.

How much pressure do you think it takes to crack that aluminum cover? It's about 1/8" thick. It would take probably a couple hundred PSI to damage it, and a crack probably wouldn't be the first damage (it would more likely bow the "flat" surface out).

A crack is a fatigue failure. It needs an explanation of why it has been repeatedly stressed and unstressed. Vibration, thermal cycling, impacts, and shock loads are pretty much your choices.