LMTV Alternator Disaster, engine now catastophic

[aleigh]

Does anyone else think this thread would be better with... pictures?

More here: https://www.flickr.com/photos/adventioneering/albums/72157667885796619

expeditionnw - it snapped off flush with the engine. the bracket went with the alternator, leaving two bolts in. I usually reach for the PB blaster and reverse drill bits, but, we'll see what they do tomorrow.

 

[Awesomeness]

Here are the specs for the long bolt.

That's going to be a really hard bolt to find. M12x1.5 (fine thread) x 200mm, Class 12.9.

Fastenal doesn't have longer than 170mm. McMaster has one that's the right diameter and length, but is coarse pitch (1.75) and only class 8.8 (about 60% weaker)... https://www.mcmaster.com/#91280a758/=1aw1gdi

Maybe do class 12.9 threaded rod? https://www.mcmaster.com/#1077n14/=1aw1hz1

 

[Awesomeness]

it snapped off flush with the engine. the bracket went with the alternator, leaving two bolts in.

The cast curved alternator bracket should bolt to the engine block with 3 bolts and 1 stud (so a total of 4 "bolts" through it). The L-shaped bracket bolts to the top of the cast curved bracket with 2 bolts.

 

[aleigh]

That's depressing about the bolt availability.

The cast curved alternator bracket should bolt to the engine block with 3 bolts and 1 stud (so a total of 4 "bolts" through it). The L-shaped bracket bolts to the top of the cast curved bracket with 2 bolts.

So I am not in front of the truck anymore but this is what I remember from looking at it. The L shaped bracket went with the alternator. The alternator still firmly seemed attached to the curved bracket. The long bolt and hardware is awol though. I didn't see anything that looked broken, but again, we'll see for certain tomorrow.

Didn't superman have A1 alternator kits... I wonder if that included the bracket, as in if I wind up needing one, I wonder if I shouldn't just do that. What's a few more days in this lovely town. Although I have seahawk tickets for NY eve. Overall I really just need to get to Seattle and then I have all the time in the world to fuss over it.

 

[expeditionnw]

Ive got the proper bolts and brackets in washougal if you want to get here. Im the mean time why not just put two small ones in place of the large one. Its not rocket science to bolt the alt down, contrary to what you may hear.

 

[aleigh]

I need to look at the TM again but I recalled it went through the bracket, but the bracket itself wasn't threaded. Isn't it the pivot or the tension? If two can go in from the ends and are threaded, great. I also am kind of figuring that an 8.8 would last a few hundred more miles.

I may take you up on the parts though if it goes south tomorrow, we'll see. Maybe I'll just move here. Settle down... Raise llamas maybe. Later when people ask I can just say, well you know my army truck broke down.

 

[Awesomeness]

The long bolt goes through the front ear on the alternator, then the whole length of the curved casting bracket, then the rear ear on the alternator. None of those parts are threaded. The bolt then gets a washer and locking nut on the back. The whole alternator is bolted in place with no adjustability - the tensioning for the belt is accomplished by a separate tensioner located further down on the front of the block, below the alternator.

As for whether an 8.8 bolt would last, that's a good question. It's a little strange that they used a 12.9 bolt, as the bolt is only in shear, not used as a tension component. It seems unlikely that vibration could shear an 8.8 bolt, so I would think you'd be ok. The bigger potential issue that I see with the bolt from McMaster is the coarse thread, which will back off easier under vibration.

 

[aleigh]

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.

 

[Awesomeness]

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.

I don't think it's possible.

What might be more likely possible is getting a 1/2" Grade-8 bolt that long, and having it fit. Or if 1/2" is too big (e.g. the holes aren't big enough clearance), drop down to a 7/16" bolt. 12mm = 0.472", but a standard tolerance clearance hole for a 12mm bolt is 13.5mm = 0.531", so I think chances are good you can get a 1/2" bolt in there, and finding an 8" long 1/2" bolt will be way easier. That will at least get you moving, and can be replaced later with the proper metric hardware.

 

[aleigh]

I don't think it's possible.

What might be more likely possible is getting a 1/2" Grade-8 bolt that long, and having it fit. Or if 1/2" is too big (e.g. the holes aren't big enough clearance), drop down to a 7/16" bolt. 12mm = 0.472", but a standard tolerance clearance hole for a 12mm bolt is 13.5mm = 0.531", so I think chances are good you can get a 1/2" bolt in there, and finding an 8" long 1/2" bolt will be way easier. That will at least get you moving, and can be replaced later with the proper metric hardware.

Yeah I agree with all that. Just something to get going. Well we'll see. Thanks everyone for the replies. I'll keep the updates coming.

 

[expeditionnw]

It would suck to get two short bolts in, but im confident it could be done. Necessity is the mother of invention and all that.

 

[aleigh]

Ok so popped the cab this morning had took a good long sober look. The alt bracket is intact and still on the engine - I was wrong before. The L angle bracket went with the alt. I think what probably happened is the long bolt worked out, the alt flopped around, and snapped off the other two. It wore a nice bright spot on the engine. Just a guess but that's my hunch.

So if they get out the two snapped bolts, find replacements, belts, I am on the road. The bad news is we pulled in after close and the guy figured we weren't coming at all, so he filled up with more jobs, and it's Friday, in Baker City... This sucks because I have Seahawks tickets w/ the gf's family for Sunday. But we'll see! Could have been much worse.

 

[expeditionnw]

Grab a pick and see if you can turn out the two snapped bolts by hand. I think you might be suprised to find they have no tension on them. A small screwdriver can be tapped to create a slot in the top of the bolt, and can be turned out that way too. No sense in waiting around for someone else to get to it, you can handle this no problem.

i think your theory is spot on for what happened. Nearly every truck ive seen has had the large bolt hand tight.

 

[aleigh]

Ugh so tip the cab down. Works fine. Pull it into the shop. No air to the manifold all of a sudden (pulled the line to check). Just done. I mean I know, put a fitting on the power pack and run it that way off the shop air, but yeesh. My luck.

 

[NDT]

Ugh so tip the cab down. Works fine. Pull it into the shop. No air to the manifold all of a sudden (pulled the line to check). Just done. I mean I know, put a fitting on the power pack and run it that way off the shop air, but yeesh. My luck.

Apply parking brake!

 

[aleigh]

Apply parking brake!

I'm going to LOL.

 

[expeditionnw]

There is a manual baclup of course....

 

[aleigh]

There is a manual baclup of course....

Not mine. It blew a seal a few days before I was supposed to take this trip so I capped the lines. I do have a spare power pack with me though if the first one gives up. The power pack on the truck is in good condition though.

 

[Awesomeness]

A small screwdriver can be tapped to create a slot in the top of the bolt, and can be turned out that way too. No sense in waiting around for someone else to get to it, you can handle this no problem.

Or get a Dremel and carve a slot in it.

My luck.

I feel you. This is how my luck always goes too.

 

[aleigh]

Judging by the fact they are welding I don't think the bolts just backed right out. Got a couple of hours here before I hit O/T. Looks like I am going to need a ujoint in the very near term though. R279X seems to be the deal, anyone get these through normal places like NAPA or is it some bizarre meritor thing? I do see them online.

And the alt holes are rounded out. Hoping I can take it to some place and get them to press in bushings or something rather than get a new unit. Probably better in the long run anyways.