Broken Crankshaft Count?

[Leadfoot]

It would be interesting to see %

How many 01-04.5 were sold vs cracked
How many 06-10 were sold vs cracked
+10 etc.

Obviously they crack/fatique over time so I'm sure the +10's will start to increase.

Also in the poll, what happens with 04.5+ and 05 cranks? Where are people voting with those?

 

[DieselmafiaLLY]

It would be interesting to see %

How many 01-04.5 were sold vs cracked
How many 06-10 were sold vs cracked
+10 etc.

Obviously they crack/fatique over time so I'm sure the +10's will start to increase.

Also in the poll, what happens with 04.5+ and 05 cranks? Where are people voting with those?

This would be some interesting info but I believe too many variables to make any correlations

 

[09duramaxP.O.S]

09 duramax 10100 miles junk

09 duramax completely stock just turned 101000 miles crank broke this thing has been a piece of junk since 30000 miles it's on its third set of injectors third transmission on its time for a new motor haven't pulled it apart yet to se where it broke but will repost as soon as I find out

 

[schulte]

Mine:

2004 LLY, 1,000whp with big twins and big fuel. Socal 3388 regular firing order cam.

Good crank was magged and balanced, no polishing required. Billet main caps, girdle, and studs. About 3 years and 50,000 miles on this build with no issues up until now. Done a few dozen hooks, 10-15 dyno events, and lots of street driving.

 

[ScreaminDuramax]

Bummer!

 

[ScreaminDuramax]

 

[LBZ]

Mine:

2004 LLY, 1,000whp with big twins and big fuel. Socal 3388 regular firing order cam.

Good crank was magged and balanced, no polishing required. Billet main caps, girdle, and studs. About 3 years and 50,000 miles on this build with no issues up until now. Done a few dozen hooks, 10-15 dyno events, and lots of street driving.

Dual fueler?

 

[LBZ]

I've done the vibration sensing. Doesn't tell the source per se. Only that the engine is shaking in time with the crank rotation. (duh) Sensing on the block is decoupled from the crank enough that you are not getting a good correlation between the crank event and the block movement.

So, only when the crank vibration is in harmony with the block's harmonic do you see the block shake violently. The Crank itself could be vibrating at several points, or through the whole spectrum and you would only see the block shake when they align.

Where did you have the sensors? Just mounted on the block or on the crank itself?

 

[schulte]

Dual fueler?

Yes

 

[LBZ]

Yes

I'm still believing that the extra load from dual fuelers or other accessories running off the front are contributing factors to crank failure behind #1 main. Ones that break in the middle I believe are harmonic induced IMO.

 

[Harbin_22]

Bone stock trucks break cranks too though.

 

[schulte]

I'm still believing that the extra load from dual fuelers or other accessories running off the front are contributing factors to crank failure behind #1 main. Ones that break in the middle I believe are harmonic induced IMO.

May be related, maybe not. For the first 40,000 miles on this build, I did have the dual fueler but the belt length wasn't right for my routing (a bit too long, not enough tension) and it would often get thrown off when sled pulling.

About 9 months ago, I completely reworked my accessory belt system (different idlers, tensioner pulley, belt length, routing) as well as switching over to the more powerful LML power steering pump and a 250a aftermarket alternator. This belt configuration was definitely under more tension and probably pulling more power off the crank. Last month I broke the crank.

Definitely possible that adding more load to the crank contributed to breaking it (after it ran fine without breaking for 40,000mi at 1,000hp for 3 years)...

 

[Fingers]

Where did you have the sensors? Just mounted on the block or on the crank itself?

Hard mounted to the block.

 

[LBZ]

Hard mounted to the block.

Would one that mounts to the end of the crank to measure vibration, rpm and shock be of assistance?

 

[LBZ]

Bone stock trucks break cranks too though.

True.
But if I recollect most of them broke in the middle, not at the snout. I believe most that break at #1 main are running extra accessories on the belt.
I could be wrong though. There have been so many used in so many different applications that it may just be a crap shoot if yours goes or not.

 

[wrcknkrw]

Some of the trucks come factory with a dual alternator in the place that the second pumps go. That just like a second pump would add stress and GM did it originally.

 

[LBZ]

Some of the trucks come factory with a dual alternator in the place that the second pumps go. That just like a second pump would add stress and GM did it originally.

I'm willing to bet a pump loads the belt a lot more than an alternator does.

 

[Harbin_22]

I kind of see the extra load thing but my OEM tensioner is still lined up between the correct tension marks. Wouldn't that be the same amount of lateral pull on the crank pulley? I could see if the tensioner was pulled way tighter maybe

 

[Harbin_22]

I don't have the clutch fan either. I would think the fan pulls more load on the crank than my injection pump does

 

[Fingers]

Would one that mounts to the end of the crank to measure vibration, rpm and shock be of assistance?

Sure, let me know what you discover.