CDD injection line issues

Clb · May 18, 2026

I am 100,000 +% sure that they
will " work" on a mock up engine...
But are they going to "fit "an asymbled and running engine?
:sorry:

This chimerica crap kills me.

offroad-anarchy · May 19, 2026

Just a side note to this exact issue. I purchased a set of the china lines off amazon for $38 or so.

They were so badly formed that I couldn't even get them attached to my rebuilt IP out of the truck.

I ended up using paint stripper and polished up my old lines then clear coated them with high temp paint. They look pretty good and went right back in first try.

So, for those wondering about the cheap china ones available out there, I'd take a hard pass.

Here's what a set of originals stripped, polished and clear coated look like. Yeah my two best friends are Moe and Ron. Put those two together and you'll get, kinda, who I be's some times

Cheers, Pete

asmith · May 19, 2026

Those look great!! I really like how they turned out. hopefully the clear holds up.

Brian VT · May 20, 2026

Am I reading this right? That these lines will throw off the timing because of the lengths being wrong?

ROCK HARVEY · May 20, 2026

Brian VT said:
Am I reading this right? That these lines will throw off the timing because of the lengths being wrong?

That’s right, you need them all to be the same length because the high pressure pulse from the injection pump takes time to travel down the line to the injector. Depending on the year and application, some IDIs have the timing adapter on the #1 or #4 line so the line with the adapter will be shorter to compensate. That’s why I measured my new lines in the first place, to find out whether I needed to re-use my adapter or if the new lines were all the same length.

Olds64 · May 20, 2026

You can get a temporary injection line that you could keep in your glovebox.

Emergency Fuel Injection Line | Fix Engine Problems Fast

Never get stranded with a broken pipe again. Keep a durable emergency fuel injection line in your toolbox to handle unexpected breakdowns wherever you are.

www.accuratediesel.com

I suppose if you had the crimping tool and access to hose rated for that pressure you could even make an entire set of injection lines for your IDI.

DougBoy66 · May 21, 2026

They also are supposed to each have the same degree total of bends (90 degrees = 2x45 degree bends) in addition to same length

MasterChiefIDI · May 21, 2026

I would imagine that if all the lines had increased length by the same percentage, timing should be just fine. You just might have to adjust base timing a little but after that, be just fine. But if not all are increased by the same percentage, I could see problems.. Maybe CDD has corrected this issue with their supplier since. Won't know w/o receiver a set and verifying. That said I have enough OE sets to make a good set so I think I will go that route instead of gambling. Thanks for the post.

Curious, I'm probably just measuring with fishing string away from determining this, but does anyone know if I can use a 6.9 passenger bank injection line set with a 7.3 driver's bank injection set? Reason I ask is I wouldn't mine riding myself of the timing adapter if I can and have a good 6.9 pass side set.

Thanks

Clb · May 21, 2026

MasterChiefIDI said:
I would imagine that if all the lines had increased length by the same percentage, timing should be just fine. You just might have to adjust base timing a little but after that, be just fine. But if not all are increased by the same percentage, I could see problems..

Absolutely

MasterChiefIDI said:
Maybe CDD has corrected this issue with their supplier since. Won't know w/o receiver a set and verifying.

Hopefully

MasterChiefIDI said:
That said I have enough OE sets to make a good set so I think I will go that route instead of gambling. Thanks for the post.

Curious, I'm probably just measuring with fishing string away from determining this, but does anyone know if I can use a 6.9 passenger bank injection line set with a 7.3 driver's bank injection set? Reason I ask is I wouldn't mine riding myself of the timing adapter if I can and have a good 6.9 pass side set.

Thanks

I've never seen that addressed nor tried it. I don't know if deleting the timing adapter has been addressed yet, but there's mentions of removing it...

MasterChiefIDI · May 21, 2026

I think I'll try the fishing string method and report back for both sets

ROCK HARVEY · May 22, 2026

MasterChiefIDI said:
I think I'll try the fishing string method and report back for both sets

80lb line worked well for me. It needs to be thick so it doesn’t have too much extra space inside the line, plus you have to be able to push it. Let us know what you find!

Brian VT · May 22, 2026

I decided to put new (China) lines on (not fun getting them to fit) when I replaced my pump and injectors. Now I'm thinking about putting the old ones back on. I was never happy with the fit and now I'm wondering if I can get it tuned better with the original lines. I get some smoke at startup and after coasting and then back on the pedal. That may not be due to the lines and tuning but now I'm curious.

Olds64 · May 22, 2026

Brian VT said:
I decided to put new (China) lines on (not fun getting them to fit) when I replaced my pump and injectors. Now I'm thinking about putting the old ones back on. I was never happy with the fit and now I'm wondering if I can get it tuned better with the original lines. I get some smoke at startup and after coasting and then back on the pedal. That may not be due to the lines and tuning but now I'm curious.

Did you time your IP with a luminosity probe or piezoelectric spark adapter after installing the China injection lines?

Brian VT · May 22, 2026

Olds64 said:
Did you time your IP with a luminosity probe or piezoelectric spark adapter after installing the China injection lines?

Spark adapter on #1 and set to what's recommended (-8, I think).

MasterBruh · May 28, 2026

Brian VT said:
Am I reading this right? That these lines will throw off the timing because of the lengths being wrong?

Yes, from an engineering standpoint lines under pressure will always swell between fluctuating flow. Each time the Injection Pump pushes fuel through every line, they will swell just a little bit. Think of putting your thumb on the end of a garden hose, it will swell up as the water pressure builds up. This happens every single time diesel flows through these steel lines until the injectors pop releasing the pressure, even if the swelling is miniscule, it is enough to mess with timing. That's why everyone here is concerned about the varying lengths.

If the line is shorter than the rest, it will swell less so your timing is essentially "advanced" in that cylinder.
If the line is longer than the rest, it will swell more so your timing is "retarded" for that cylinder.

That's how I understand it. I hope that makes sense :yell:

CDD injection line issues

Clb

Another old truck

offroad-anarchy

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asmith

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Brian VT

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ROCK HARVEY

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Olds64

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Emergency Fuel Injection Line | Fix Engine Problems Fast

DougBoy66

That is a HORRIBLE idea!!!!!! What time?

MasterChiefIDI

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Clb

Another old truck

MasterChiefIDI

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ROCK HARVEY

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Brian VT

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Olds64

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Brian VT

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MasterBruh

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