Your exhaust manifolds may be leaking. The studs normally break off due to the engine moving on the rubber mounts. I believe people even have had their flange bolts break.

 

I wished that what i am hearing is a turbo. I wouldnt mind it at all then. Heck id love to drop a 6.7 or even a 5.9 CTD in this thing. Just wishing, back to reality now...

I am not really noticing any exhaust leak, but that being said, I have 2 broken exhaust manifold bolts. My smelling is kinda messed up right now, so i cant smell any exhaust fumes. But that may be a good angle to look at this, as an exhaust leak could make a whistling sound at higher exhaust pressures, i.e. when on the accellerator. (sorry grammer wasnt my favorite class in school)

When i contacted the dealer for the first time, they told me that it could be the motor fan. But today they did say that the front ring and pinion is bad, and they wont have it fixed till wednesday or thursday when the part gets in, and i am stuck drivin a fricken neon on snow and ice till i can get her back.

 

Yeah wasnt it like mostly the 05s and 06s?

 

So I've been working on this issue with my 6.7 cummins, you know, about the exhaust pressure thing?

One of the guys in the Cummins forum finally got his into the shop and they said he had 3 leaking exhaust ports. A new gasket solved his problem completely. We were worried it was our turbos. whew!

Like I said. I know they're different systems but, the same exact sound should come from the same place right? Just under slightly different circumstances.

Exhaust pressure is high for both the 4.7 and the 6.7 under acceleration. But high aswell only for the 6.7 under deceleration due to the turbo and exhaust brake.

Shouldn't be to hard to diagnose at a shop. They have those super smeller dohickies that detect tiny amounts of exhaust gasses.

 

So i finally got my truck back today! They got rid of the humming/whining noise. They said that they fixed the exhaust bolts first, and took it for a test drive, then they lifted the truck, and stuck a stethascope to the front differential, and it was the cause of the whine from the front. It made the noise the most between 45 and 60 mph. THey found that the orrigional ring and pinion had 0 backlash, while specs call out .005 to .008 backlash. FrenicX, I deffenately do believe what you were saying about the exhaust pressures. I dont know which did it, but its not making the noise any more. Maybe something else to consider.

 

Whats the verdict Frank?

 

Is there any 2wd guys with this problem? If so, that might just narrow it down for ya a little bit.

I guess that the easiest thing to do is to check out the exhaust manifold bolts, IMO. Then if you have access to a lift, raise it up and check out the front diff. Id start with the "cheaper" and "easier" thing to fix/diagnose first.

 

The cummins I told you about is 2wd.

Is the front drivetrain always moving on the Dakotas up to the transfer case or do they have some kind of auto-lockout? If it doesn't move it can't make noise.

 

My current truck is full-time 4x4 (awd, 4lock, 4lo) but i had an 06 that was part-time, and somewhere, i read (maybe in my jeep book) that you have to back up for everything to "unlock" when in 4x4 goin into 2wd. I noticed that when i went into 4lock, the truck shuttered, like it had posi-trac, but when i reversed, it went back to "normal." What was wierd was that it didnt sound like any "gear whine" that i have heard before.