Heavy 200A alternator hanging off the cylinder head? (6.5L)

[T9000]

Maybe this was discussed before and I couldn't find anything about it...I am not a mechanical engineer, but looking at the way the 200A alternator is attached to the driver side cylinder head (I am talking about the 6.5L, but maybe it's the same on the 6.2L), it doesn't feel right.
Statically the weight distribution could be OK as most of the weight could be taken by the lower bracket (#4), given that the 3 bolts (#9 & #10) on the cylinder head were tighten after bolts #1 and #16 under the alternator, on the bracket attached to the engine block. Either way there will be constant stress if the bracket is made slightly on one extreme of the tolerance, but if the 3 bolts (#9 & #10) are tighten last, any potential play around them will go towards alleviating the bracket push or pull stress instead of adding to it.

And dynamically, things appear a lot worse...if you look at the longer twisted bracket under the alternator, which is almost twice the length of the upper bracket and with only one support point vs three, it seems that it would have a lot more flex than the heavy bracket on the cylinder head, meaning that when driving over bumps and rough terrain, the alternator will try to bounce up and down (let's leave aside any longitudinal and lateral forces during accelerating, stopping and turning and focus just on the Z axis for now) due to its heavy mass and all the flex in the lower bracket (#4) will get transmitted via the 3 bolts (#9 & #10) on the cylinder head and get absorbed mostly by the front TTY bolts closer to the first 2 cylinders and maybe the third.

The stress would increase significantly if the lower bolt(s) #1 and/ or #16 securing the alternator to the block bracket #4 (bracket #3 is not present on my truck serial # over 300k) ) would get even slightly loose as then even more of the alternator mass will get transferred to the front cylinder head bolts trying to pull them upwards everytime when going over bumps.
With the constant up and down (Z axis) vibration, over time, I can see how the front area of that cylinder head TTY bolts could start giving in, making it easier for the gasket to leak in that front corner. Unless I am missing something, I would think that trucks with the heavier 200A alternators (and maybe the 400A too if are secured the same way) are more prone to having this issue and maybe it happens more frequent on those engines/ alternator combinations.
I would prefer for the whole alternator to be supported only by the block without applying any additional stress to the cylinder head, which is already under a lot of pressure at higher RPMs.
Or at a minimum, the 3 bolts (#9 and #10) should be secured with shoulder washers/ spacers that would have some type of sprung play equivalent with the [ lower bracket flex + potentially loose screw #1] combined play.
But ideally, that alternator should be secured directly to the engine block, not via the cylinder head TTY bolts.
Is my thinking in the woods?

 

[Action]

I do not recall the three bolts in front of head being TTY. I dont think the TM even gives a torque spec for those.
Get the correct parts pages for your truck.
put it together and drive.

 

[T9000]

I do not recall the three bolts in front of head being TTY. I dont think the TM even gives a torque spec for those.
Get the correct parts pages for your truck.
put it together and drive.

Yes, the three bolts holding the alternator to the head are not TTY.

What I meant is that the alternator is connected to the block indirectly via the same TTY bolts that hold the head and it applies additional stress to one’s towards the engine front.
Instead, its whole weight, or most of it should be connected directly to the block, not to the head.

 

[Mogman]

Like Action said, you are overthinking this, just make sure everything is good and tight and recheck them after a few hours and during annual maint

 

[T9000]

Like Action said, you are overthinking this, just make sure everything is good and tight and recheck them after a few hours and during annual maint

Ok, let’s set aside bolts #1 & #16 being loose, that’s the worst case situation.

The lower bracket is about 1/3 the mass and twice the length of the upper bracket and it has only one support point vs three, therefore it will flex a lot more during driving, especially over bumps or rough terrain.
When the lower bracket flexes, most of the alternator mass under acceleration will be transferred to the head, putting additional stress on the TTY bolts in the engine front area.
Given the alternator mass, that can be a lot of additional stress when hitting bumps / road cracks / potholes at freeway speeds or when off-road on larger rocks.
I hope I am overthinking it and would feel better if the alternator was connected only or mainly to the block, not to the head.

 

[Mogman]

Thousands of them out there!!!
just put a 60A on if you feel it is going to wreck your head, otherwise what is the purpose of this exercise? are you going to tool up and machine a different mounting bracket? If so I think that is great!
If your assertion is correct about the TTY head bolts then there would be a history of head gasket failures at the #1 cylinder.

 

[Action]

Feel free to reinvent the wheel. This setup works fine for us and AMG. Why do you think your bolts will be coming loose? Improper install?

 

[Coug]

I had the short bracket that went to the exhaust stud.

Because my exhaust manifold wasn't machined flat, it put uneven pressure on the exhaust stud.

My truck sheared that exhaust stud twice in a couple thousand miles.

I replaced the short bracket that went to the exhaust stud with the longer bracket that goes down to the block.
Thousands of miles later it's still doing just fine.

Yes, it is a lot longer than the one that goes to the exhaust. However, it is pulling in a straight line, and doesn't flex. It's pulling against the force of the serpentine belt, so even as it bounces around it's still primarily under tension.

It sounds like you are worried also about the cylinder head bolts having additional stress from the generator weight on them? I've never heard of the cylinder head bolts having issues in just the front corner, even with the 400 amp generator system that's a lot more weight.

It's a non issue, so don't stress about it when there are much better things to stress about

Sheared generator bracket bolts.

When I first got the truck(m1123, 200 amp generator) the stud on the exhaust that holds the rear generator bracket was sheared, and a couple of the front bolts were loose. It started making noise again, so I checked, and the exhaust stud is sheared again, and at least one of the front bracket...

www.steelsoldiers.com

 

[T9000]

Thousands of them out there!!!
just put a 60A on if you feel it is going to wreck your head, otherwise what is the purpose of this exercise? are you going to tool up and machine a different mounting bracket? If so I think that is great!
If your assertion is correct about the TTY head bolts then there would be a history of head gasket failures at the #1 cylinder.

You are exactly right, and I don’t know how many have blown gaskets in that front area. I brought it up just in case it is more common and usually very few try to correlate why a gasket blew in certain area vs another.
From what I read, blown gaskets are relatively common, maybe RWH can comment or others that work on them in higher numbers.

EDIT: in a meeting, will come back with more info

 

[T9000]

I had the short bracket that went to the exhaust stud.

Because my exhaust manifold wasn't machined flat, it put uneven pressure on the exhaust stud.

My truck sheared that exhaust stud twice in a couple thousand miles.

I replaced the short bracket that went to the exhaust stud with the longer bracket that goes down to the block.
Thousands of miles later it's still doing just fine.

Yes, it is a lot longer than the one that goes to the exhaust. However, it is pulling in a straight line, and doesn't flex. It's pulling against the force of the serpentine belt, so even as it bounces around it's still primarily under tension.

It sounds like you are worried also about the cylinder head bolts having additional stress from the generator weight on them? I've never heard of the cylinder head bolts having issues in just the front corner, even with the 400 amp generator system that's a lot more weight.

It's a non issue, so don't stress about it when there are much better things to stress about

Sheared generator bracket bolts.

When I first got the truck(m1123, 200 amp generator) the stud on the exhaust that holds the rear generator bracket was sheared, and a couple of the front bolts were loose. It started making noise again, so I checked, and the exhaust stud is sheared again, and at least one of the front bracket...

www.steelsoldiers.com

Good to hear that it should not be a problem. I was just researching the engine and ways to increase the power and I constantly heard about blown gasket on these engines.

 

[T9000]

Feel free to reinvent the wheel. This setup works fine for us and AMG. Why do you think your bolts will be coming loose? Improper install?

I don’t know why they would come loose, but reading around the forum, found some comments saying to check the alternator bracket as it sometimes gets loose and thought maybe it’s a known problem.