I've f'n had it with custom lines. PLEASE HELP!

m880cummins

m880cummins

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Apr 29, 2013
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So I built this 12v this spring and did my own intake and bent my own lines. Lines were from columbus. I bought 7 originally (1 as a spare) and in the 14000 miles I have put on the truck, it just broke a 4th line tonight. The lines run me $60 each and every time, they have cracked right between the collar and the flare. Can't even really see the crack but it is there. Going to magnaflux them friday to get pics. I'm just fed up with this. Plenty of clamps, no sharp bends and the lines sit properly before being torqued and clamped. Could it be poor quality? They are mild steel .084 36" long lines.

Thanks for any help in advance.

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Charlie
 
I had the same problem, except it only took me about 500 miles to crack 4 lines.

All my lines are tied together in two diff spots. I noticed that when the truck was running they were vibrating up and down ALOT, like about 1/4". I made a bracket that bolted to one of the center bolts that holds the intake manifold on. The bracket runs up and is bolted to the bottom of my line clamp that is in that area. You may have to make two brackets the way yours is set up.
 
Also pay close attention when torquing them that the line isn't twisting with the nut. You may try a lube under the nut and on top of the ferrel to allow the nut to slide and not twist the line
 
Thanks guys. Idk im careful how much i torque them and they dont vibrate at all
 
I cannot help, BUT do you have a build thread going with that super sexy work of art I just looked at???!??
 
Sorry to hear about the bad luck man. I've been told or read somewhere that at Cummins factory lines are stress relieved after the bending process by bead blasting them. I want to say it was internally? Is there a site sponsor or anyone know of where a guy could ship their lines to have this done? Not trying to derail m880 just see if I can help provide a solution fer ye. :Cheer:
 
Those look like stock line clamps? How about trying the rubber isolated ones from haisley machine. They look like they would soak up more vibration then the plastic stock ones.
 
Mooner1 said:
Sorry to hear about the bad luck man. I've been told or read somewhere that at Cummins factory lines are stress relieved after the bending process by bead blasting them. I want to say it was internally? Is there a site sponsor or anyone know of where a guy could ship their lines to have this done? Not trying to derail m880 just see if I can help provide a solution fer ye. :Cheer:
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You could anneal them. Anyone know what grade SS they are? You can look up a chart and see what temp and how long they need to be there to relieve all stresses. Shot peening actually puts in more stresses which makes materials harder but more brittle, so I don't think that's what you want in this situation. Also, for isolation, you want the base mount to be ~50 times stiffer than the thing it's isolating (the lines in this case), and then your rubber will be effective. Otherwise, it's not really a shock absorber, it'll just change the natural frequency which would take you a lot more trial and error to get right, and would most likely just give you more mass and more force on the lines.

I'd start with building a mount that grabs onto the engine personally. Annealing could be a very good thing too.
 
Is the flare formed right on the end of the tube, or is it a separate press on end?

Formed flares should be illegal, 5/16 OD lines solve a lot of problems.
 
Yeah, make riser/brackets coming off the intake runner bolts. That's a lot of weight sitting in the middle transferring putting stress and vibrations onto the line ends.
 
CorneliusRox said:
You could anneal them. Anyone know what grade SS they are? You can look up a chart and see what temp and how long they need to be there to relieve all stresses. Shot peening actually puts in more stresses which makes materials harder but more brittle, so I don't think that's what you want in this situation. Also, for isolation, you want the base mount to be ~50 times stiffer than the thing it's isolating (the lines in this case), and then your rubber will be effective. Otherwise, it's not really a shock absorber, it'll just change the natural frequency which would take you a lot more trial and error to get right, and would most likely just give you more mass and more force on the lines.

I'd start with building a mount that grabs onto the engine personally. Annealing could be a very good thing too.
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Sounds like credible stuff here. I guarantee the factory has processes for their engine specific lines that these straight lines don't have done to them.
 
9724VF350 said:
Is the flare formed right on the end of the tube, or is it a separate press on end?

Formed flares should be illegal, 5/16 OD lines solve a lot of problems.
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Can you elaborate? I don't think I've ever noticed if they were one way or the other.
Do you have pictures of both ways?
 
So a local shop gave me a new stock line to get me up and running. Rebent it to fit and it runs again and will get me home tonight.

One thing i noted is the OEM line is MUCH stiffer than the columbus diesel line. Also, the collar on the cummins line does not move freely like the columbus line.

More clamps will help but i would like to find a way to stress relieve them. They ALWAYS break under the collar by the flare. So I would assume that columbus needs to stress relieve the swedge they make on the line.
 
Formed flares are pretty much always going to be the weak link in any hard line. I use them all the time in mobile refrigeration applications. There are a huge amount of applications that use flares in a mobile environment. The one thing that you will always see in any OEM application is a good sturdy mount right near the flare. If I fail to secure one of the copper refrigeration lines near the flare I will probably end up having to fix a leak there at some point down the road. If you build a good mounting setup to keep those lines steady it WILL improve their reliability. Although I'm pretty sure that the OEM lines are probably the toughest out there for our motors. Good luck bud.
 
Back from magnaflux. All lines had the same kind of crack right at the base of the formed flare. 6 lines total :bang I think the sliding collar on the lines does not aid in strength being a different meta (stainless on mild steel lines). Cummins lines have the collar as part of the flare.

Stock 12v lines are tempered mild steel. I have a friend with a P7100 24v who is having trouble cracking scheid lines. He said he is reaching out to a guy named John Pezan of JP diesel. Anybody know of him?

I just want a set of lines and it be my last set of lines for the truck....

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Charlie
 
I'm running JP diesel lines, no problems here on either of my 24 ppump trucks. The half a dozen I've ppumped I've used his lines and haven't had any breaks, leaks or cracks yet. Mild steel and there good lines and cheaper if I remember correctly. Never ran stainless but reviews and complaints have steered me away. People think you need big size lines......,.078 and .084 is the biggest most need to go. Leaves some more Meat and strength from what I can figure than using the bigger lines.


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Last edited:
Thank you for the info! Are his lines very difficult to bend by hand like an OEM cummins line? Also, does he use a sliding collar between the flare and the nut? Is the nut and collar (if applicable) stainless or mild steel?

Charlie


Johndeere60 said:
I'm running JP diesel lines, no problems here on either of my 24 ppump trucks. The half a dozen I've ppumped I've used his lines and haven't had any breaks, leaks or cracks yet. Mild steel and there good lines and cheaper if I remember correctly. Never ran stainless but reviews and complaints have steered me away. People think you need big size lines......,.078 and .084 is the biggest most need to go. Leaves some more Meat and strength from what I can figure than using the bigger lines.


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Click to expand...
 
Make sure when you install the lines, leave one end off while torquing the other end on. If the line jumps up or down you can then see it and re-bend as necessary, so it drops in place at both ends with one end tighten in place.
 
Has a sliding collar, and there easier to bend than the OEM lines from my experience. I'm sure the nut and collar are mild steel but don't take as gospel. I thought they were chinnsy to be honest but the more I hear they are better than other lines.


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