I'm putting this here hoping to help you. Once again, due to the complexities with this problem and the lack of being able to get in front of every single manufacturer and person involved, this MAY NOT BE FACTUAL but I've exhausted every effort I can at the moment to get to the root cause of the LB7 Injector failure.

I've been through 3 sets now all done at the dealership by quality people that I know personally so trust and work ethics have not been a concern thus far.

After speaking with Cody at http://industrialinjection.com/

It seems that Bosch did actually "fix" their early problem a long time ago.

However, the LB7 has something that none of the other versions have... Corrosive fuel lines -

The "bent" high-pressure fuel lines going through the valve covers (8 of them that look like brake lines) are the "real" problem according to Industrial Injection.

They claim that the 2 inch area below the retainer nut and lock corrodes and flakes off not only as it's pulled out but also drops small debris as the tech reinstalls the lines into the newly installed injectors.

According to Cody, this can and often times does begin a brand new failure within minutes, days, weeks etc.

They have a machine and a treatment process that goes way beyond "blowing out the fuel lines with an air hose". They have a chemical that cleans and treats the ends of the fuel lines so that they may be reused versus having to be replaced.

He states that if the dealer isn't cleaning them properly, they are re-introducing the issue all over again as a very small 4 micron particle will bounce around inside the injector and begin premature wear and failure along with helping to clog the injector. This is symptomatic with hard-to-start problems.

He further adds that if the correct methods of installation are followed, you should only need to replace the injectors once which equates to an expected wear life of about 200K miles.

Apparently, it's common expectation to replace fuel injectors of this type at or around 200K. That makes a little more sense to me but I somehow expected to pay this type of money for a truck and not have any "real" major repair for well over 200K.

Obviously, that's my feeling or opinion and it isn't based on having this ongoing problem with fuel delivery on any other truck in the past.

So - take it for whatever you think it's worth. I'd like to hear from anyone who disagrees or has any info to prove this theory wrong.

In this instance, I'm merely re-hashing what I was told and I truly don't know if it's right or wrong. It sure seems to make sense though when you realize that many, many of my techs customers have had more than 3 sets replaced on their respective LB7's.

I emailed this to my buddy who works on the Dmax program, will let you know if he has any input.

Awesome!

Wouldn't you think that the sharp minds at GM, ISUZU, Bosch would have found this if it were true? Let's see....

In the beginning, I would suggest the answer to be "no".

But, after knowing how many sets of injectors Chevy has paid for along with the labor to remove and reinstall them, I have to believe that someone, some engineer, some tech at a dealership etc would have caught on to this.

They have spent a FORTUNE on this recall. I'm talking a lot of money. They don't like it when this type of thing happens.

Wouldn't the shear cost of the job drive them to take a closer look at those fuel lines especially when some of the small pieces would wind up in your hand while working on it?

I don't know. Industrial Injection claims this to be a constant "unknown" or "overlooked" and that the alloy those lines are made of is different than fuel lines on models later than the LB7.

Seems to be a bit of a stretch in my mind but what do i know?

Here's his response. Looks like he put some time into it so help it gives you some idea.

This is kind of a vague problem, but here is my feedback...

I've gone through many diesel injectors on the dyno for various reasons and I've actually personally rebuilt diesel injectors to swap to different nozzle geometries. I've also failed some of the high pressure diesel pumps due to misuse on dyno. So, I definitely do have some experience with diesel fuel systems.

Current Piezo injectors operate at 2000 bar (~29,000 psi) and even the older common rail systems with solenoid injectors operated at about 1600 bar fuel pressure. They open and close very fast compared to conventional gasoline injectors. We often use as much as five seperate injections in one combustion event. Knowing this, you'd expect that there is a lot that can go wrong operating at such high pressure and such high needle opening speeds if the component is not used properly.

I am not personally aware of this issue with the fuel lines. However, I am aware of a few things that can cause failed injectors.

1) You can re-use the fuel lines, but it is not recommended, and I think it is mandated by GM to replace them if you take apart the fuel system. You risk having a burr from the threads chipping off and flowing into the injector. The injectors I have worked with do have an internal filter, but you're still better off avoiding this situation.
2) Coking is a fundamental problem with diesel injectors that can cause flow dispersion and eventually pre-mature failure, but I'm not sure if there is anything the customer can do to help prevent this. Running near peak power for extend periods of time (heavy hauling or marine use) will definitely reduce the life of the injector.
3) Bad fuel. There's always the risk of getting bad fuel and I personally would avoid biodiesel, it's nasty stuff.
4) Too much temperature - if you "chip" your Duramax and go to higher exhaust temperatures, you "can" over-temp the fuel nozzle and seize the needle. I've done it before on dyno.
5) Improper installation. Installation of the common rail fuel system is tricky. When you install the fuel system, you introduce a lot of air into the system and it's difficult to purge all of the air. The installation needs to be done exactly as the GM instructions indicate. If you run the injectors dry for any amount of time, their life will definitely be shortened.
6) Don't run out of fuel.
7) Improper sealing. This is critical. The technician who installs your injector needs to make sure the mating surface in the cylinder head and the shim are completely clean and free of debris and tar. It is very common to have a bad seal if you don't check the sealing surfaces. Hot in-cylinder gases can pass by the injector shim and into the injector bore and overheat the injector. If you pull out an injector and it's covered in black tar that seems to be as hard as epoxy, this is what happened.

Long story short... the injectors "should" last their advertised lifetime as long as they are installed properly and not abused. You have to look at these things case-by-case, but I would attribute most injector problems to those two categories. Good diesel techs are hard to find. You need to find someone that will follow the GM installation instructions line-by-line.

I have a common rail test stand to test these injectors, we do a couple sets a week of LB7's... we run them up to 1700-1800 bar if needed and we vary the pulsewidth and pilot injection pulse widths as needed... a lot said above is true, however I have not seen the internal pipe corrosion problem, but I have seen the effects of biodiesel on an LB7 and it's NOT very pretty... i'll try and help if I can

Hi,

What is your price to rebuild them (8)? Do you have the ability to install different nozzles etc and do you guys agree with a claim that simply modifying the injectors makes additional power with ZERO changes to any other part of the truck?