Chatter under light/no load

[2013megacab]

When driving around town, towing or not, when I unload the drive train by matching engine output with drive train speed, i.e. neither accelerating or decelerating, I hear a relatively soft but detectable chattering sound. Best guess is it is u-joint slop. Is this normal, or something I should have looked at?

Thanks,

Al

 

[Newsa]

How many miles? Do you have 4x4 & annually lube your front drive shaft?

Get it looked at before a drive shaft comes up through your floor board.

 

[2013megacab]

Thanks.
Yes I have a 4x4. I bought it used with 22K on the odometer. Carfax said it had recently been serviced at the original selling dealer. I have owned it for about a year and put 24K on it. I read the service chart but somehow missed the annual lube requirement.

Al

 

[LarryM]

2013megacab, My 2011 does the same thing, your description is spot on. I asked a neighbor who works at an independent shop and he said that it is a rattle from the torque converter/transmission interface when they float with engine and driveline at no load conditions. I also asked a diesel rep at one of the sorry dealers here and he said "That's normal". That reply is listed on page one paragraph one in their excuse book. Anyway, mine has been doing it since new. There's a guy in our Chevelle club who has a Laramie dually CTD with Aisin and his does it also. I don't know what to think about it, maybe one of the techs here can shed some light on it, it is curious........

Larry

 

[Bob4x4]

Are you sure it is a mechanical noise and not just a different engine sound from a timing change due to load or lack of load

 

[LarryM]

Bob4x4, It sure sounds mechanical to me. What does the engine sound like when the timing changes? It really sounds like a metallic rattle, only happens at low speed "float" not loaded or unloaded. So far nothing bad has come from it, it's just there and begs the question, hoping that it is not a forewarning of impending issues. Maybe it's just the "nature of the beast" and the dealer was right, "it's normal".

 

[2013megacab]

+1 what Larry said. I'm reasonably sure it is a mechanical noise. Only a very slight change in accelerator, up or down, makes it go away. No significant change in load or RPM. It sounds like bearing chatter to me.

Al