I noticed lately that my truck makes a rattle/ticking(tough to describe) noise. It is coming from the motor. I hear it when im on flat streches and cresting hills. when im going up hill or accelerating hard it doesnt do it or when im going down hill. I had my valves adjusted and fresh oil change but it still is there.

 

Mine has a hell of a tick too and the motor was just rebuilt. I went back to the dealer and they said that's how they sound. Hopefully somebody else can chime with some help. It doesn't sound right to me either. Could it be injector rattle or valve lash probs.

 

I think I have the same on my 07 5.9. I have asked on here and at the dealer for quite some time. Mine does it only when Accelerating with load. Sometime w/o a load but not as noisy. Tried everything. As soon as you let off accelerator it goes away etc... I think it is just normal for these things.

 

My '05 had 207k on it when I got it. Same symptoms as you just listed. Mine would tick/tap while cursing with no load on it, tapping would increase with rpm's and be most noticeable @65mph & up (1,850 rpm). As the boost would rise the tapping/ticking would decrease until @~15psi boost and up then it couldn't be heard anymore.

I took a Saturday and adjusted my valves myself. I'm just an average DIY'er and it ended up being an easy task. I Googled "cummins ISB valve adjustment" and followed the steps I found. All my clearances were noticeably loose. I adjusted them all back to the recommenced spec's of .10 intake & .20 exhaust.

I know you said you had your valves done... but if you paid someone they might of just "checked" the clearances as technically Cummins says you don't have to adjust them unless they are outside of their very broad range. The problem I have is I don't think one intake should be .15 and others .08, .06, .10, ect... Technically those are all within the spec'ed range... but not right IMHO.

Anyway, adjusting my valves took care of about 60% of the tapping I was hearing... I then added 2-cycle oil as suggested here and that reduced my rattles about another 20% it seems. Truck now sounds like it should.

 

The rattle on light acceleration is very common on 06 -07 trucks. Mine has done it since day one. It did it even after having all 6 injectors replaced and the valves adjusted, I now have 102K miles on her. The rattle is less in the winter time and more when it's warmer out. My guess is it is the ECM playing with injection timing to meet some stupid tree hugger epa rule.

 

About 3 weeks ago i bought a 70,000 mile 2006 Diesel and i also have the problem stated above, it`s driving me crazy. The truck runs perfect but that noise has me thinking i got a lemon.

 

exact same thing with my 07 no tick /rattle in the winter but once it gets hot out it starts up again

 

i have the same tick with my '05 with 57K+ miles on it. I have not tried adjusting my valves and the truck runs great. But I have come to the conclusion that it is common some louder than others but mine does it at idle and varies with rpm.