Upon acceleration from a stop in 2nd gear I get this growling noise. It seems the slower I accelerate the louder it is and it's just the opposite when I accelerate faster. What causes this and how do I get rid of it? I just bought the truck several mounths ago from a friend and I noticed it when he drove it also. It's got an nv5600 with 35,000 mi. on it.

Thanks for the help.

 

If the growl is at lower RPM's and quits at about 1200 RPM then this is normal with the NV5600. It is gear growl caused by the engine as it slows and then excellerates with each compression stroke, at least that is what I think.

I replaced the harmonic balancer with a fluid damper and it reduced the growl a lot but did not completly eliminate it. The fluid damper for the 6.7L is less expensive than an after market damper but requires more work to install.

 

Thanks again for the help. Strange that a different harmonic balancer is the fix for that.

 

On later models they added a dual mass clutch which smooths out the engine output. That clutch doesn't last as long and winds up causing vibrations.