Loud "rumble" when towing

[Dalmus]

Hi all,

Frequent reader, but a new poster. You folks have helped me figure out quite a few issues with my truck, from tire selection to the dreaded rear diff whine.

I've searched the forums, and don't know if I'm just not using the right phrase, but I haven't been able to find any references to my particular problem.... here goes!

I occasionally (4 -5 times per year) tow a pair of ATV's up north, about a 200 mile trek. The combined weight of the trailer and ATV's is about 2,400 pounds. I've got a factory class II receiver on a 6 cyl 4.0 so I should be good for 3,500 pounds, even if you include me, my dog, and my Stuff.

Intermittently, while towing this load at speeds above 40mph, there will be a loud "rumble" sound. Its akin to the frequency that a bad muffler produces in that it is very low-pitched, it drowns out normal radio and conversation. This noise can be present while traveling uphill, downhill, or on a level section of road. It doesn't seem to be related to acceleration; when I take my foot off the gas and coast, the sound does not diminish.

Any suggestions as to what might be causing this? Could this be a highly exaggerated chatter from the rear diff? Would a diff oil change possibly address this? Is this symptomatic of the larger ring and pinion failure?

Or am I on the completely wrong track?

Thanks for any advice!

Ryan

 

[Minivek]

when my wheel bearings were on their way out it was making a noise very similar to a prop plane, it didn't vibrate much, but the noise was definately a low rumble.

 

[peteypie]

I also had the same problem, it again ended up being the wheel bearings. It might do it when you are trailering b/c the drive train is under a heavier than normal load, stress, strain whatever you want to call it. If this is the case your bearings are only going to get louder, even under normal driving condition, however this is not one of the "bigger" issues with these trucks.

 

[Dalmus]

I'm well aware of some of the other problems! I bought the truck used with 42,000 miles, luckily I got an aftermarket warranty, (anybody buying a car from EVS should invest in one...) and within about 10 days of driving off the lot I had to have about $2,000 worth of warranty work done... clutch pack, two front bearings, and a few other odds and ends. Since then, no problems except a strange whistle from the engine that only appears in the winter, and only occasionally while maintaining a speed.

Of course, now that I'm about to hit 100,000, the Michelins need to be replaced, I just spent an afternoon doing brakes and rotors for the fronts, and I just swapped out the rear diff oil (filthy!) hoping to eliminate the dreaded Acceleration Whine (about 50% effective). I'm really hoping I'm one of the statistical few that don't have to have the diff rebuilt!

I'm getting a new set of Michelin Cross Terrain SUV's mounted on Saturday... I'll have them check the bearings as long as the truck is in the air.

Thanks for the suggestion!