Straight Skinney on Injectors

[dually2002]

Does injector failure relate to fuel filter design (OEM) and poor fuel quality, lack and lubracation properties in the fuel or is more of a design failure. Are the OE replacement injectors rehab turn ins, modded turn ins or new with design fix? Only have 70K on my 02 use Donaldson fuel filter (Every 15K) and Amsoil fuel additive and no signs of injector problems yet. Don't want to fix something that ain't broke.

[OC_DMAX]

The following is my opinion:

First, there have been several versions or tweaks of the LB7 injectors.

The original injector design (2001 to mid-2002) had several flaws.

1) First, they suffered cracked injector bodies which caused fuel to spray outside the injector and subsequently into the valve train. This fuel eventually worked its way to the oil pan and mixed with the oil (lowering the viscosity). Thus you hear about fuel coming out of the oil breather tube on the front of the motor. As I understand it, the crack injector bodies were from either flaws or mis-calculation in the original treatment of the metal that created the injector body itself.

2) Second, they suffered from "ball seat erosion" which allowed excess fuel to flow in the return line. The net effect was that the injector was not completely shut off (my understanding, someone correct if wrong). Ball seat erosion could be caused by improper fuel filter design (among other things),,,,, and surprising enough, GM changed the design and went to a dual pleat filter. I suspect there are other parameters besides fuel cleanliness that can cause ball seat erosion, others can comment.


So to answer your question: The failures are partially related to fuel quality and partially related to sub-standard (or defective) design (my opinion once again). The fuel quality part we can deal with (added filtration) while some of the design issues are out of our hands.

As time marches on, I suspect that Bosch has redesigned the internals at least once (pure speculation on my part). You seldom hear of massive fuel leaks from the cracked injector bodies anymore (most of those have already occurred - if they were going to happen). I suspect they have fixed this in the 2003 and beyond trucks. The injectors themselves though are still not lasting the intended 200,000 mile interval that was the original design goal (whether remanufactured or new). I also suspect that GM/Bosch is not spending serious money going forward trying to resolve the remaining issues. The LB7 has been out of production now for 3+ years, it is long ago history for them. Interesting enough though, you do not hear about too many injector failures with the LLY version of the motor. So it is possible to make things work. This is what I would really be interested in: why do the LB7 injectors still seem to have a higher failure rate than the LLY injectors?


Thats my input, others can correct, comment or add.

[More Power]

why do the LB7 injectors still seem to have a higher failure rate than the LLY injectors?

Just my opinion.... Bosch likely said, we can correct the problems experienced by the LB7 injectors while the LLY injector is still on the drawing board, and make servicing the injectors a lot easier. It's harder to make major changes to an already designed part once it's been in production for a while.

Jim

[OC_DMAX]

Probably so. Its always easier to engineer a product the second time around after you know what your mistakes (or weakness) are on the first generation. Been there,,, done that.

[Kennedy]

Does injector failure relate to fuel filter design (OEM) and poor fuel quality, lack and lubracation properties in the fuel or is more of a design failure. Are the OE replacement injectors rehab turn ins, modded turn ins or new with design fix? Only have 70K on my 02 use Donaldson fuel filter (Every 15K) and Amsoil fuel additive and no signs of injector problems yet. Don't want to fix something that ain't broke.

The answer is: Yes


As for the replacements, that varies. Used to be all new, but now lots of remans being used. I believe they only reman certain vintage/series injector cores.