Whats the story on #4 injector line cracking due to loose support clamp?
 

I watched some youtube videos and some websites say #4 is redesigned for the clamp (is now rolled, longer support with a black insert). Now I decided to look at all of mine. Injector lines 2-6 have all the blue clamps, all the same. I took a small 5/16" ( I am sure its metric but it worked anyway) box end wrench and they were all snug, but I was able to tighten all the clamps a little more on all 5 lines.
I dont understand this claim that #4 is most likely to crack than the others, seeing they all use the same blue clamp and number 1 has no clamp at all.
I am glad I did tighten up all 5 clamps.
Is tightening the clamps going to solve a loose clamp, it seems like by how it is made, that it can be tightened, as if the central plastic hole wears loose over time, but as tight and stiff as the little bolt is, I cant imagine it coming loose.
I have 160,000 miles on the engine.
My clamps do have a small bolt and they can be tightened.
Anyone care to comment?
Example videos

I found the same and did the same as you. But I then ordered Cummins #4 updated fuel line and replaced mine. Convenience/insurance for $40. These lines could break for any number of reasons: metal or insulation inconsistencies, tube design, supplier location....most things have a lifecycle anyway. The lines have tails of fuel at 5-20k+ psi flowing thru them, so that has an effect I think.


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Yes, they do. But no sense the #4 is going to fail sooner to me anyway. Several are about the same length. Notice #1 has no clamp. Does not need a clamp, why is that... since its longer?

The reason for them breaking from the googling I did, was the clamp gets loose because the bolt backs off, the line vibrates and metal fatigues. So if the clamp is not loose, all of them should stay ok.
The new design for #4 has better longer support, no bolt used. But did they redesign all the clamps on the other 4 lines?
I would be curious as to what % actually have failed.
Seems to me oddly strange.

This line is something everyone with a 5.9 24v needs to consider attending to one way or another.

A guy I work with has a 04.5 and he has had #4 injector line fail twice on him. He has around 265k on the truck.

Put small dabs of red permanent locktite on clamp bolt and nut threads. Torque and let set overnight for locktite to cure

I have fixed quite a few third gens with the failed #4 line.

Lots of highway shop vultures out there charging to save a HPCR diesel owners butt on lonely deserted freeways and the back country remote roads by charging $250++ to change out a broken HPCR feed line.

Always carry a spare #4 new upgrade style in truck parts + tools if one still have the OEM factory POS #4 in or travels far from home and doesn't like getting wallet raped.

Running high RP, high RP duty cycle tunes or pressure box will kill even the new upgrade HD injector lines. Even blows out RPRVs.