[tkemo648]

Yesterday on my drive to work I noticed my 2006 GMC 2500HD with the LBZ had a ticking/knocking sound at speed. When you are coasting you cannot hear it, slightly noticeable at idle. The truck seems to have more vibration at idle than before as well. Wanting to rule out the possibility of a broken crank i took the video below:

When I looked at the balance rates this morning after the truck was warm they were as follows:

Cylinder #	In Park	In Drive
1	0.3	1.1
2	-0.1	-0.6
3	0.4	0.1
4	0.3	0.5
5	2.5	4.5
6	-0.0	-0.4
7	-0.8	-1.7
8	-2.4	-3.2

I am looking to get it into a shop soon but I am hoping its one, or more, bad injectors.

The CP3 was replaced at 238k in August of last year. The truck currently has 256k on it.

Anyone else had a similar issue and care to share the outcome? I have saw several posts with similar issues but most all never have the diagnosis or outcome posted as a follow-up.

 

[tkemo648]

I finally go to look at it some this morning. I have the knock, no smoke, balancer had no play in it. I started in hooking injectors on the driver's side bank and when I got to #8 the noise was gone when it was unhooked. That should indicate that #8 is the culprit.


I'm gonna try a healthy dose of cleaner. If that doesn't help I'll be ordering a replacement injector.

 

[tkemo648]

Follow Up: The strong dose of injector cleaner didn't help. The knock persisted and I ordered a Bosch reman and just finished the installation (solid two thumbs down). The knock is now gone and the truck seems to have a little more pep in it's step. The #8 injector must have been on a slow decline and finally started hammering. Hopefully this helps someone in the future with a similar issue.

 

[OkDually]

Follow Up: The strong dose of injector cleaner didn't help. The knock persisted and I ordered a Bosch reman and just finished the installation (solid two thumbs down). The knock is now gone and the truck seems to have a little more pep in it's step. The #8 injector must have been on a slow decline and finally started hammering. Hopefully this helps someone in the future with a similar issue.

Glad that you got the issue resolved.
Thanks for giving us an update!