Are your nuts dry???

[Mark Rinker]

As part of my recent spate of injector issues, I have been informed by my dealer that the root cause (and reason for their warranty) is the design of the early injector lines. They pointed out how water can pool at the flare nut, making its way to the threads on the injector, causing corrosion and eventually making its way into the injector body.

After the injectors and lines are replaced, they use sealant to cover the exposed flare nut to injector area, making it impossible for any water to seep into the threads. On my 2001, at least two of my injectors were 'wet', or showed signs of dust attraction to diesel that was making its way outside the injector top before the injector failed.

On my 2002, everything is visibly dry and tight, but I still have at least one failed injector from the signs of all the grey smoke its belching.

Thought I would pass this along for early LB7 owners. You might want to take a look sooner than later. If your flare nuts are wet/attracting dust, corroded or if you're starting to smoke at idle, get to your dealer sooner than later. Also, if you need lines I have a source that has >50 sets and is selling them for $50 per set. GM gets over $800...

[Kennedy]

I would have liked to see some form of umbrella seal on these myself. That and fill the cavity with dielectric grease or similar. The injector lines are left exposed to the outside so that in the event of a leak at this high pressure joint, they leak externally rather than fill the crankcase.

Suffice to say, if they aren't leaking externaly, they are sealed well, and the debris/trash is not in the injector until you loosen the nut. Before they leak in, they'll leak out with 23,000 psi inside...

[DmaxMaverick]

While I know what your dealer is talking about, it has nothing to do with the reason for the 2001/2002 injector failures, and the campaign. John is right. The problem with crud and/or moisture collecting at the injector nut can cause a problem of corrosion at the nut and line, but does not effect the injector internally. Long before you'd have crud and moisture leaking in, you'd have high pressure fuel leaking out, of the fuel line/nut. The other part of that issue is the possibility of any crud that collects there can fall into the injector during removal. The instructions for preparation to prevent this is very specific.

The cause of failure pertaining to the injector campaign is 100% related to internal failure. Ball seat erosion, specifically.

My thoughts are of a redesigned upper valve cover. Surely we can come up with a cover that isolates the injector and fuel lines from the head internals. In any case, the nut/line point needs to be protected from the elements, with grease, RTV, putty, etc. I like the idea of a rubber umbrella seal, but unless it were really tight, any moisture that does make it in, would cause issues at a quicker rate.

[More Power]

It's important to bring the engine up to operating temperature after washing the engine - to evaporate whatever settles into the injector fuel line nut area. I like the idea of silicone sealant. I wonder what mechanics think of servicing the injectors that have been previously sealed with a bead of RTV?

Jim

[Mark Rinker]

I had the tech explain this to me again today (truck number two in for warranty injectors) and it was my misunderstanding of the information that lead to my erroneous posting.

Anyway, the if any lines are showing corrosion, they too must be replaced to keep contamination out of the NEW injector during re-assembly.

If anyone wants a set of new OEM LB7 lines just in case, email me at mark_rinker@hotmail.com.