Does anyone know why my 2003 3500 Duramax with 23,000mi would be making a knocking sound at about 1800- 1900rpms. I know about the fuel knock at 2600rpms, but this is a little concerning. I have towed a two horse trailer with my dually and it has labored with about 6000 lbs of weight. Plus it has been going thru fuel more than it should. I changed the fuel filter, air filter, oil, and added diesel Kleen (which is a great product), and although it runs a lot better, it still has a knocking going on that simply doesn't sound right.


Need some help to tackle the dealership to fix the problem.


DuraBachhttp://www.dieselplace.com/forum/smileys/smiley5.gif

pilot injection maybe..........


Thttp://www.dieselplace.com/forum/smileys/smiley4.gifNY

My guess would be injectors.

Injector messed up causing fuel knock. Same problem, had to wait until I had a hard start problem before dealer could do something about it. Even with that noise it didnn't throw a code and the balance rates were within spec. New set of injectors fixed the problem.

Keep an eye on your oil, incase it starts to dump fuel into it.

Mine had the same noise until I got the injectors replaced.

My truck started that noise at 7000 miles, it was never something I could find on the tech 2 either, I took plenty of snapshots trying to see what was going on, and I finally replaced my injectors last week (7900) and the noise is gone. Go figure.

Sounds like the injectors are the winner!


I will take on the dealership tomorrow. They have a few other things to fix as well. Like the ball joints, that instead of replacing they tightened up. They gave me new tires because the tires it came with were worn, due to the alignment out. I put the new tires on, come to find out they were 'el cheapo'. It rained the day I put them on and found myself hydroplanning on every puddle. New tires will coming my way too. I run my own business and would never do any of my clients this way.


Stay tuned!


Durabach, out to get one back for the customers!