Rear End Gear Howl

[Mike Wenrich]

Just came back from a 1000 mile camping trip and noticed my 2004.5 2500 4x4, 150K, has a noticeable howl between 72 and 75 MPH. Goes away after that and it only howls on torque or when you are leveled out on cruise. Let off and it goes away. So a little more background, I have complained since the truck was new because I could hear a low (35-55) howl. Under warranty bearings were replaced and after no improvement a one piece drive shaft was installed. Slight improvement after that but still made a slight noise. Over the years my hearing worsened and I now live in a mountainous area where speeds of 70+ are not possible. And for several years I had a 3500 RAM for camping use.

So I'm thinking that maybe the howl is from a ring gear or some other problem in the rear end. It's a limited slip axle BTW. Over to course of the 400 mile trip one way it became very annoying. Any ideas on what may be going on? Just got new tires too so it's not them. There is a distinct howl that I believe is coming from the transmission when cold that has been there for years but it does not sound the same. I figured I would address that when the trans was rebuilt. Otherwise shifts fine and no clunking from the rear.

 

[Ozymandias]

Mine howls for 100K now, it will howl another 100K I think.
I got used to it.

 

[Jim W]

When was the fluid last changed in the rear axle, take a sample of the oil and see what debris are in the oil? it could be several things from a BRG going bad, to a thrust washer that is wearing out or some other item in the differential? Could it be the one-piece drive shaft u-joint at the rear differential also making noise?

Sound (noise) is funny it is very hard to place exactly where this is coming from when you sit in the driver's seat. So, this sound could even be a wheel BRG going bad and it is more notable at the higher speeds.

So, these are just thoughts as where to look and it could be something totally different.

 

[Mike Wenrich]

I did get used to mine at the lower speeds and this one might be something to work around since I don't often travel at the higher speeds. Maybe earplugs??? It's not terrible. Just annoying and maybe the forbearer of something that will need a repair. I don't believe it is a bearing though. Likely would make noise at all speeds. And this is the first time I have had a vehicle that howled on torque. Had others that howled when letting off the accelerator. As in a pinion bearing.

 

[sag2]

It is more than likely a ring and pinion problem. I would do an oil sample and see what that tells you, but I would lean toward just leaving it alone. A new R&P is expensive and there are not many shops that actually know how to set one up properly. Bearings should be addressed, but gears will last a long while making noise.

 

[Mike Wenrich]

Thanks all for the replies. I agree Sag. Ring and pinion did cross my mind. I have always believed that was the earlier problem at lower speeds which still remains, but my hearing has degraded more than the increase in noise. Until now at higher speeds. I turned the radio sound up and it went away. Cheap fix.

 

[p-Bar]

My 04.5 howled also. Took it in under warranty and there was a TSB for it but they said it didnt . Sold the truck at 220k on the clock and never changed the rear end oil cause I was pissed about it.