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If you guys haven't seen this already.

 
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Thanks for posting this...I love his teardowns...always fund to watch. Man, he got hosed by his friend on this one. Water in the block, 1 damaged head etc.

I mean, the rods might be salvageable, but I cringe when I see him hammer on fracture surface of the rod. That is really a red flag for using these rods and caps again. I doubt he is going to make his money back on this one. The CP4 has been out in the weather, the block will require serious machining if it can be salvaged.

The break in the crank looks similar to the one posted on another thread several years ago from member Knunn11...that was a 142,000 mile engine but stock. This engine didn't appear to spin any rod bearings, but did have wear. Those crank main bearings near the rear are pretty worn for that mileage and for a person who used an Amsoil filter and probably good oil and maintenance practices. Root cause?-- harmonics, bad batch or cranks?...I guess we wont; really know.
 

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Thanks for posting this...I love his teardowns...always fund to watch. Man, he got hosed by his friend on this one. Water in the block, 1 damaged head etc.
He assessment was partially in error however as some of the water in the block was there as a result of rain. He seemed to make the assumption that some of the water was part of the issue with the oiling, that's not the case however as there was no milky oil.

I mean, the rods might be salvageable, but I cringe when I see him hammer on fracture surface of the rod. That is really a red flag for using these rods and caps again. I doubt he is going to make his money back on this one. The CP4 has been out in the weather, the block will require serious machining if it can be salvaged.

The break in the crank looks similar to the one posted on another thread several years ago from member Knunn11...that was a 142,000 mile engine but stock. This engine didn't appear to spin any rod bearings, but did have wear. Those crank main bearings near the rear are pretty worn for that mileage and for a person who used an Amsoil filter and probably good oil and maintenance practices. Root cause?-- harmonics, bad batch or cranks?...I guess we wont; really know.
Sure nice big rods though...

Something that really stood out to me but I might have missed a part being removed... the oil pump gear seemed to be retained the same way Nissan did it... friction only using the harmonic balancer. It's really really weird to see a gear on a crank that has no key and can free spin if it's not clamped in place.
 

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I rewatched this video. It looks like the exhaust valves on the right bank, rear most cylinder lifted and contacted the piston.

At the kind of rpm these engines can spin, contacting the valves would certainly be a stressful event for the crankshaft. However, I genuinely believe this crankshaft failure is just a symptom of the real cause of failure. If the rotary valve gave up, it's certainly possible the exhaust pressure would go into the triple digits. My observations suggest the ecm relaxes the rotary valve at 61psig of exhaust pressure. Apparently this engine was tuned and there are plenty of ways the turbos could be setup for performance that would cause massive spikes in exhaust pressure that the ecm would not be fast enough to respond to.

The right rear cylinder appears to be closest to the turbocharger and to me, would be the natural first spot for the valves to lift.
 

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Hard to know right?...I wanted to explore the bluing issue. The comments on the YouTube video absolutely slam the engine and the "blue" crank. To the effect of "...this POS just burned itself up..." Emphasis on POS in many comments. Well, from what I can tell, the blue color is there from the factory. Is this a nitriding or other heat treatment? Take a close look at the first picture below. It is from the Columbus plant assembly line during the run of the engine. Sure looks to me like the the rear counterweights (see arrows) are the same blue color. And even a hint of it on the rod fillet.

Now look at the pictures below that. Those I took today of the engine I bought almost a couple years ago from a guy in WV who had the serious bad luck to have a camshaft literally break in half at about 40,000 miles. He just replaced the whole engine. This engine is in fine shape (minus the busted cam, which, really fortuitously didn't cause valve to piston contact and I have the bearing, rings etc. now to rebuild the shortblock) There is a lot of blue on the counterweights as well. All over really. Doe this look much different than the ~120,000 mile engine?.... BTW, this engine is a January 2016 build with the "old" crankshaft part number.

I sure wish there was an answer or refutation to the "blue" = extreme heat and abuse assumption.
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Another totally unscientific opinion. There have been too many cranks break in 17 and 18 model year trucks to have this only be an issue with early 2016 cranks (the old part number). There may be some validity to this in terms of a bad production run, but there is more going on I think as the "new" part has broken as well.

I think, in squeezing this block length into small block territory---and when you look at these things on a bench opened up, they look small frankly--they may have taken too much material out of the crank fillets and counterweight widths. They are just darn thin for the torque this thing produces.

And, another reason I will keep running 5w-40, is when you look at the rod bearings, jeez these things are small with the tiniest retaining indentation I've ever seen. The rod itself is stout, but not wide and the bearing--well, it is just narrow like a small block. The copper in the upper shells in the video is just scary. Oil pressure and quality is the only thing keeping these from spinning.

Having said all that, are the cranks destined to break or spin rod bearings?...probably not, but good to be aware and do the maintenance right. I enjoy the heck out of mine...it is a cool engine. And if it breaks, well hell...it breaks.

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Loved seeing the block tore down- great find on this.

A few observations:
-the discoloration more or less proves that these failures are due to excessive heat. The cause of that heat- I don’t know.
-the engine is very well built- over built in some areas, which is neat to see
-it seems (from pictures I’ve seen) to always be the rear of the crank that fails. Pretty interesting.
-the rod journals have way more wear than I expected.

So, about the heat issue.

Does this engine run too hot, overall?
Does the oil run too hot?
Is there a lack of oiling in the rear of the engine?

I‘d love to have a one of these broken cranks to send to a metallurgist and a pro race engine builder.
 

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@QuikCoastie17 The discolouration is isolated to the one section, that is almost certainly the result of of the friction from skipping over the remainder.

Remember, tuned engines, especially turned up ones, the ecm is trying to increase egt through fueling and increasing the friction in the cylinders via timing.

Looking at the evidence, I’m almost completely certain this failure is from the exhaust valves lifting.
 

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Discussion Starter · #9 ·
Next oil change, I’ll open up the upper oil pan to look at the crankshaft, just for the hell of it. As we speak, my truck is 130,500 miles. The engine is at 70,500 miles. We’ll see about the color at rear end.
 
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I watched again, just facisnated by this and want to understand. I was wrong about the crank, it’s blued all across. Most of the rods are not discolored. So that’s confusing.

The interesting thing, is that the exhaust valves have a significant impact on only one cylinder. There is an outline of the intake valves, but nothing like how the exhaust valves interacted.

The answer is in the metal. It doesn’t lie. Missing part of the picture.
 

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I watched again, just facisnated by this and want to understand. I was wrong about the crank, it’s blued all across. Most of the rods are not discolored. So that’s confusing.

The interesting thing, is that the exhaust valves have a significant impact on only one cylinder. There is an outline of the intake valves, but nothing like how the exhaust valves interacted.

The answer is in the metal. It doesn’t lie. Missing part of the picture.
Maybe that one cylinder was affected because right before (or right after) the break, the broken piece of the crankshaft sent that end to the top and stuck there. It’s the last cylinder on the right bank and that’s where the it broke.
 

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That is the point I was trying to make in my post above--look at pic #1 from the factory....the (visible) crank counterweights are blue at the start.....the violet/blue hue is easily contrasted to the gray of the iron block next to it.
I’ve seen the same as a result of high friction in failed rotating components… so my brain went straight to that.
 

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Yes, I hear you...normally a result of heat. I wish we knew more about that coating and why it is there--assume some sort of crank surface treatment?....
Looks like some kind of heat treatment with such uniformity and color. Heat treatment on the crank would make sense at these power levels.

The isv only has 45mm center to center for crank throw, the duramax is the next closest at 50mm.
 

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I am pretty sure that the coloration on the crank is from an induction heat treat process during manufactoring. The heat is induced in the metal using electro magnets. I have seen other videos that talk about this process discoloring cranks in large industrial diesel engines.
 

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I feel as though the harmonic damper is to blame. On one of the many other crankshaft threads in this forum, someone posted the OEM harmonic balancer specs and it shows a max 240hp. It seems as though Fluidamper isn't going to build one because there isn't much of a demand for this particular application. I did reach out to ATI Performance and they said they needed an order of at least 10 and that there is an extended lead time to build. I am not familiar with ATI parts, but they seem willing to build one for the 5.0 Cummins. Any thoughts.
 

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I feel as though the harmonic damper is to blame. On one of the many other crankshaft threads in this forum, someone posted the OEM harmonic balancer specs and it shows a max 240hp. It seems as though Fluidamper isn't going to build one because there isn't much of a demand for this particular application. I did reach out to ATI Performance and they said they needed an order of at least 10 and that there is an extended lead time to build. I am not familiar with ATI parts, but they seem willing to build one for the 5.0 Cummins. Any thoughts.
The fluidamper is the only one worth getting, since there is nothing to actually fail in it.

There is a couple of things that compound this:

The AC compressor, it’s a very capable compressor and puts significant load on the engine and can produce a fairly noticable shock everytime it cycles.

The transmission, due to the way the engine is tuned the tranmission can shift harder than it really needs to.

Being an oversquare v8. One of the issues with old cummins over square v8s is that they beat up crankshafts. The lower piston velocity coupled with the additional stresses caused by the power pulse being contained over a shorter period of time. This is somewhat alleviated by the way multi shot injections smooth the combustion process.

The emissions, have the engine wound up so tight it’s constantly under load no matter what it’s doing.

Being a v8, means less main bearings to keep everything in check.

I wouldn’t scoff at a 245hp rating on the balancer either. That might still be more than the amount of counteraction that’s actually required.

The crankshaft failures that have occurred are likely a combination of factors that the small sample size still obscures.
 

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The crankshaft failures that have occurred are likely a combination of factors that the small sample size still obscures.
I'd agree...all of your points are good ones. In an effort to reduce weight and size, they (Cummins) squeezed a ton of horsepower and torque into the size of a small block--and then increased the HP and torque even more at Nissan's request. The concept of being "overbuilt" like the Cummins straight 6 engines is pretty tenuous with the ISV....it is on the ragged edge I think.

Think about the 7.3 International Power Stroke V-8 from 1999. A hugely heavy large block iron beast with ridiculously small HP and torque compared to today. And no emissions of course. That engine and the ISV are like the difference between a Clydesdale and a Thoroughbred horse. The thoroughbred is more fluid, graceful--dare I say artful--and faster off the blocks. But more subject to wear and tear and unpredictable broken bones (in its skinny legs) that usually end its working career long before the draft horse peters out. It sure is fun to watch them run while they are healthy though--sort of like the 5.0.
 
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