RiataAg

2001 dodge 3500 dually - 6 speed - 206k miles

Couldn't find anything exactly like my issue using search, hope you guys can help narrow it down based on your experiences -

The noise: sounds almost like exhaust drone but it is NOT constant - the howl/whine has a rhythm to it

When: as far as I can tell it only does it in 6th gear, but the noise doesn't start until about 62 mph - If it makes the sound in 5th its drowned out by the engine turning 2600 : )
Driving up an incline on the fuel in 6th gear at 60 mph absolutely no noise, starts at 62mph and gets louder the faster you go.

Noise quits as soon as you let off the fuel - it's only under power/load.

I was thinking maybe 6th gear bearing, but why at 62 and not at 60.

Replaced carrier bearing and u joints about 45k miles ago -

Replaced front bearing assemblies about 25k ago

Thanks in advance for any help -
ra

RiataAg

Or maybe it's something in the transfer case?

- I forgot to include its 4wd

The rear end is full of schaeffers - tranny is 6 qts I think of factory oil last changed about 20k ago -

With 206k and to be safe befor a case gets busted on the T case or before a mainshaft gets broken would anyone suggest I pull them both and have them rebuilt?


Any thoughts?

SIXSLUG

I'd start by draining and inspecting fluids, check u joints and axle bearings, pinion bearing and driveshaft center bearing if it has one..

Does it still whine as you let off the fuel and come down past 62 mph or just under acceleration??

RiataAg

All the fluids is full and all have been changed in the last 25-30k miles

It only does it under acceleration and only starts at 62mph, the faster you go the louder it gets but at 60 mph and under acceleration there is no moaning - just purring along like it should.

There is not any vibration, no loss of power, no drivability issues.

The noise stops as soon as you let off the fuel regardless of speed.

Here is the scenario:

Driving along at 60mph in 6th gear and all is normal, accelerate and and 62 the rhythm moaning/droning/howling starts as you keep accelerating toward 70 the noise gets louder but stays in a slow rhythm - let off the fuel to coast and it stops immediately.

Last night I checked the u-joints and carrier bearing and they all seem fine.

Hoping someone has had this problem before and already figured it out ?

I'm leaning toward a bearing somewhere in the drive train except I would think the bearings would have more load at 55 and 60 after just shifting into 6th gear as opposed to the "magic number" of 62 mph

johnh

sounds like a bearing in the trans

1-5-3-6-2-4

nv5600 have a tendency to take out the od bearing. they need over fill by a liter for sure to help lube that back end. probably too late for yours at this point though. it'll start to howl at whatever speed the harmonics dictate. and I'll bet as it deteriorates further, the speed and load that it makes the sound at will change with it. if it doesn't do it in 5th only 6th. sounds like the countershaft actually. the path of power doesn't go through the countershaft in 5th. its direct. but might be the 6th gear itself. no way to know really until you pull it apart though. might have a look in the pto ports through first, see what you can see.

I had a 5600 apart that had a failure like that. spun the bearings destroyed the housing. not even good for a core. don't let it get away on you.

RiataAg

Thanks for the replies - I was expecting tranny -

I'm sure some have, but I personally have never had a truck need rear wheel bearings nor the ring and pinion or carrier bearings a courses I've never run one low on diff fluid

I bought this truck with about 150k on it and I've run the tranny with an extra qt in it since then - has 205k on it

I'm sure it's different for everyone but tranny failure on most of my other dodges was around 220k-250k - but none of those had the 5600 so they had other problems and didn't sound like this.

I leave this truck hooked to a trailer so its towing 90% of the time, but I unhooked it today and drove it about 100 miles and never could get that sound again.

Gonna hook the trailer back up Friday and pull it just to see if it happens again -

Either way I'm going to start looking for a shop in N TX to go ahead and rebuild before something breaks.

Guess ill post another thread about that -