Mine was not mag'd. It would have been seen if it had been mag'd, it was my original 125k mile crank so I assumed it was good.
Cranks
- Thread starter Fingers
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IMO these very minor flaws are not the root cause.
Back to the original graphic I posted.
It does show the stressed area rather clearly, but is not an accurate representation of the forces on the crank. Some of that is because of the limitations of my FEA software. For instance, I can only do static force analysis. Bounded motion and harmonics are not possible nor are multi-element models. We will have to work around those limitations.
Back to the original graphic I posted.
It does show the stressed area rather clearly, but is not an accurate representation of the forces on the crank. Some of that is because of the limitations of my FEA software. For instance, I can only do static force analysis. Bounded motion and harmonics are not possible nor are multi-element models. We will have to work around those limitations.
Has anyone ever X-rayed a crank shaft to see if there are flaws? if it can be done for welds it should be able to be done on cranks. could it be induced from high timing in lower rpm's? probly not since some fail in stock motors. just throwing it out there.......ok so i'm subscribing haha
Not that you could fix it, but I do know they had issues with high stress flight hardware that was forged in the presence of nitrogen, oxygen, or hydrogen. Switching to a vacuum process during mfr fixed it.
The most notable case was that DC-10 that blew the engine rotor disk in the #2 engine and crashed because the rotor explosion cut the hydraulics. It was titanium though. It was fixed by changing the mfr process, not by redesign.
The most notable case was that DC-10 that blew the engine rotor disk in the #2 engine and crashed because the rotor explosion cut the hydraulics. It was titanium though. It was fixed by changing the mfr process, not by redesign.
Lets stick some numbers in here instead of going on conjecture.
A chamber pressure of 3500 PSI produces a load on the crank from a single cylinder of about 45,000 lbs. This happens between 7°-14° ATDC.
A 10 gram swinging weight 4" from the center produces a 22.542 lb radial force on the crank.
I'm looking for the loading from the accessory belt and the loadings from the water and oil pumps. Need the loading for the CAM too.
With those, I can calc the radial and thrust loadings on the crank.
A chamber pressure of 3500 PSI produces a load on the crank from a single cylinder of about 45,000 lbs. This happens between 7°-14° ATDC.
A 10 gram swinging weight 4" from the center produces a 22.542 lb radial force on the crank.
I'm looking for the loading from the accessory belt and the loadings from the water and oil pumps. Need the loading for the CAM too.
With those, I can calc the radial and thrust loadings on the crank.
My boss and mentor for many years was an expert witness in the investigation of that one....I can tell you more about that than you ever wanted to know
Good information. Does this 45,000 psi take into acount the compression from the next cylinder in the firing order? 40psi of boost being compressed down 16 or so times multiplied by the surface are of the piston would add alot of stress on the crank wouldn't it? not that anything can be done about that.....LOL might have just made myself look like a dumbass but oh well.
gm isuzu doesnt build them... why not switch firing orders empire diesel has had great luck with a powerstroke(i think) firing order
Where are the aftermarket cranks letting go in relative to stock cranks or are they just a different subject?
I could be wrong, but I believe Winberg is the only company to not have a failure in a duramax. I understand they are fairly new to our market, but they are probably worth their premium if that is in fact true.
1500 bucks is one reason... If that is the true fix then it would be worth it but I don't think they have enough of them out there to prove it is the fix. I'm not sure how you could, when one breaks at stock power and another holds 1000+ hp.
billet grinds are about that much, our billet 6.4 cams are 1200 fwiw. I dont care if they are proven time and time again i wont ever run an empire product.
Won't different valve springs change the cam loading?
Do you think the cranks and or blocks could be flexing and the deflection under load affecting the structure?
The cranks are twist forged correct? If so would that align the molecules in a certain order or direction in the area the crank was twisted hot?
The failures are from flex fatigue, not twist.
Don't forget that as soon as the crank breaks, the journals lose their oil supply through the broken passage way in the crank. So crashed bearings will be seen on at least some cranks.
Don't forget that as soon as the crank breaks, the journals lose their oil supply through the broken passage way in the crank. So crashed bearings will be seen on at least some cranks.
How so? Mine broke enough to start slapping the piston skirt, but not break completely apart. Oil supply was still sound, mains 1, 2, and 3 had bearing wear but had not spun. The mains all the way back to 5 were later found to be about .0035" off from center at their worst and main bearing clearance had supposedly been set to .0030"-.0035"
How so what?
The bearings in the dmax will hold out fairly well when the oil supply goes away, but not forever. So you will see crashed bearings on some broken cranks, but not all cranks that break will have bearing issues.
My point is, from what I can tell, spun bearing are NOT the cause of the crank breaking.
Also, from what I can tell, the support from the #1 main is inadequate.
The bearings in the dmax will hold out fairly well when the oil supply goes away, but not forever. So you will see crashed bearings on some broken cranks, but not all cranks that break will have bearing issues.
My point is, from what I can tell, spun bearing are NOT the cause of the crank breaking.
Also, from what I can tell, the support from the #1 main is inadequate.
To (somewhat) support that theory, I had a LMM I pulled apart that had a spun rod bearing that was bad enough to take a considerable amount of material out of the crank journal and it did not break the crank.
I say somewhat supports because it was at the rod location a spot forward of where the cranks always break.
Not sure if that helps any or not.
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I was asking how every broken crank causes oil supply to be lost through the broken passageway in the crank.
I agree with you, obviously, that spun bearings are not the main cause and that they are not even always a result, but I was giving an example of a broken crank that did NOT lose oil supply to the journals.
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