2005, Quad, 4x2, 1500, Hemi, 20", rims 3.92, 15000 miles, ALL STOCK! I only use 89 octane gas.

Here's the deleima...Dodge has been absolutely no help!!!

Got a noise I belive is the engine and not the trans at 1700-1900 Rpm at any speed or pretty much any gear (hard to tell in 1st or 2nd gear). It's not the tires or rims, trust me! At highway speeds when the engine is running in that RPM range, usually about 70mph, I get a moan that resonates through the cabin. It's hard to pin down exactly where it's coming from. It gets louder the more output your asking of the engine, in other world the more the gas pedal is pushed down the louder it gets. This all started out gradually and has been getting worse and worse. I also tow a 7000lbs, actual scale measured filled up weight, travel trailer. When towing that sucker and going through that RPM range it is MUCH louder.

I had the noise before I bought the trailer and the first time my wife and I went on a trip we noticed the noise increased quite a bit at hightway speeds. When we were on our way home there was a slight grade to the road and in 3rd gear it was right in the RPM range and the moan was so loud I pulled over and expected to find pieces of the drivetrain / engine / trans and a oily mess all over the place.

Took it into Dodge and they tried the harmonic weight that gets attached to the exhaust system, didn't do a dang thing. They basically said "yep, we hear it but don't know where it's coming from." Also told me that a few mechanics say their trucks do the same thing but not quite as bad, just one of those things. Basically told me that I just need to drive it and until something gives out they won't have anywhere to start to try to fix it. Great, hope I'm not far from home when it does die.

Since then it has been getting a little louder it seems and now I'm noticing that if I'm cruzing at say 45-50 and I give it a little more input on the gas pedal just to accelerate without downshifting, it's now moaning at 2000-2700 as well. A friend of mine has the exact same truck that I took out to test drive and his sounds absolutely nothing like mine, has none of the symptoms. Got another friend who didn't think he heard it in the beginning but when I showed him the latest his eyes got real big. Another guy asked me when I did the intake and exaust on the truck when we took a spin at lunch, he was totally surprised when I told him it was all stock and not supposed to sound like that.

I've done all the diagnosing I can think of here's the list:

Does not do it if you are in drive, at a stop, and brake torque the engine to the 1700-1900 range
Does not do it if you are going downhill in the RPM range
Does not do it if you rev the engine with the transmission not engaged.

Does do it when cruzing in the RPM range, any gear.
Does do it louder when accelerating through that RPM range
Does it same volume when towing trailer on a flat highway
Does do it even louder when accelerating uphill through the range
Does do it even louder than that when going up a grade towing the trailer

Does it with medium acceleration without towing (not sure if I want to attempt towing right now)
Does it with a 500lbs motorcycle in the bed, not any louder as far as I can tell comparing to empty.

Tires have been rotated and balanced, not an issue. Regular oil changes and all proper maintenance with proper lubricants (got documentation to prove it all). Again, everyting is stock (except the radio). The truck will also hesitate alsmost to stalling out if the engine is "cold" sometimes when I first take off after it sits for a few hours. "Cold" means sitting outside in 80-100 degree weather.

HELP???


Also forgot to add...At idle the engine is noisier than other Hemis I've heard. Gas mileage seems to be going down. Used to average an easy 18 on the highway and now I'm luckey to get 16.

 

From what you've described, I'd take a looooong hard look at the differential. It's the only location that that would be under added stress in the situations you've listed as having the most noise....

Actually. The exhaust would be louder under those cases too.... but I'd still start by going over the diff with a fine toothed comb... if that's not the culprit, look at your cats, resonator and muffler.. None of the above should fail at 15k miles, so it should all be covered.

Try another stealership's disservice department.

 

Arrowman, thanks for the suggestion but I don't think it can be the Differential. If it was it would be speed dependent, trans output, instead it's trans input dependant suggesting it's engine related.

Exhaust is solid and mounted well, don't think it's that.

Although, since it's gotten worse in the 2000-2700 range maybe something is loosening up in the Diff, any suggestions on testing your theory?

 

Two things come to mind immediately - wheel bearings and/or a u joint. I would look at the u joint first. I've had vehicles do this exact same thing and 90% of the time it was one of these two. I could also be axle bearings. These will also have those same symptoms.

 

...it sounds to me like the diff goin bad..if the sound comes only with "stress" placed on it i would look long and hard at the diff or something in the rear axle... I'm only saying this cuz mine did almost the same thing...and it got louder and louder over time...when I would accelerate or put pressure on the diff the whine was deafening.... I changed out my rear for 4.56's and the whine has gone away...

 

Ok, I can see the diff, but the moan is dependant upon engine speed not drive shaft or wheel speed. Any further info I can use to back this up. I want to collect as much information about the problem and possible solutions before taking it back to the Dodge dealer and they "dodge" fixing the vehicle again.