Turbo whine or Differential whine?

[JERRYKAM]

Guys,



I have a 06 CTD auto 4x4. At approx 50-60mph under very light acceleration I hear a very distinctive whine, especially if the rear sliding window is open. I have, at least to this point assumed it was turbo whine. However, the whining seems like it is coming from the rear of the truck. On a smooth straight road when the whine is present I have engaged 4 wheel drive to see what affect it would have thinking that if the whine was being caused by the rear differential it would quiet down. This seems to be the case sort of. I can't convince myself one way or the other.



Can one of you folks characterize turbo whine for me. In particular where does the whine seem to come from?

 

[DBoggs]

Yours is doing the exact same thing mine is. It is the rear diff. Turbo whine is a higher pitch than the sound from the rear end. I looked mine over real close when I changed my diff. cover and saw no evidence of anything wrong, I guess some of them just do it. I don't even pay any attention to mine anymore, especially since it goes away above 60mph.



Turbo whine tends to sound more like a jet engine spooling up and comes from the front of the truck. Before I removed my silencer ring and modified my airbox I could barely hear my turbo whine.



If you are too concerned about the rear end take it back to the dealer and have them check it, though I bet they won't find anything out of the ordinary.



Duane

 

[JERRYKAM]

Thanks Duane,



After searching the forums I've concluded that differential whine is not isolated. In some cases the whine was the prelude to failure. In others it was simply "the way it is", like yours and hopefully mine. I suspect the cause can be attributed to the individual machining variations and adjustments between each differential as they come off the assembly line. However, it does make one wonder where the line is between normal whine and whine related to an impending failure.



I'm going to change the diff gear oil, inspect for "metal" and see if the whine changes in any way. As you suggest a trip to the dealer for a "warm and fuzzy" check out is also a good idea.



Jerry

 

[DPKetchum]

Its a BIG differantial. Some whine is normal and with the slider open is a more pronounced noise. The AAM axels seem much more quiet then the Danas did. Just my 02 worth.

 

[GaryCarter]

Man, I'm sure glad I didn't get a slider... don't need any more worries.



I would characterize a diff whine as sounding somewhat like a power drill; the turbo just like a jet engine as someone said.



The turbo does whistle nicely at light throttle acceleration, a fact that keeps interfering with me getting better mileage. Sometimes I put my foot in it just to hear the sound.



Gary