Front end rumble/shudder

[upandattem]

Hi all. I've got a '08 3500HD 4x4 crew cab, long bed with about 52,000 miles on it that has a recent issue I am unsure on how to diagnose. The problem is worse in 2wd. If I cruise along at 60 mph and let my foot off the pedal I hear a very loud groan or roar, and if I start to use the brakes I feel a shudder. The shudder isn't felt in the brake pedal.
If I put the truck in 4wd the noise and shudder sensation are not heard or felt. This noise and sensation can be felt when the brakes are applied at 30 mph on down. Again, none of this occurs when in 4wd only 2wd.

Any thoughts?

Thanks,

[DmaxMaverick]

First things first....Welcome aboard!

Your problem sounds like a failed wheel bearing. You can check this by jacking up a front wheel. Try to move the wheel in/out, pushing/pulling at the top of the tire (don't rotate the wheel while pushing/pulling). Rotate the wheel to several positions, repeating the push/pull. If it moves at all, at any position, the bearing is bad.

A less likely suspect is a CV joint. Check this by grabbing the joint and try to move it in any/all directions. It's best to do this with the wheel jacked up by the control arm, keeping the shaft as horizontal as possible, with all stress off of it. If it moves (other than rotation), it's bad. The usual first indicator of a bad CV joint is a ruptured boot. Cause and effect goes both ways, with this one. A bad boot will cause a joint to fail. A failed joint can cause the boot to fail.

It is normal to be felt less in 4x4, due to the drivetrain winding (stress), which tightens up everything.

"Normal" lifespan of the CV's and hubs vary between 30K and forever. It all depends on the initial quality of the individual parts.

[upandattem]

Thanks Dmax for the welcome and input. I will check this tomorrow and post back what I find.

[upandattem]

Just an update. I jacked it up this morning and no play in either front wheel when I pushed/pulled at top or bottom of tire. If I grabbed the sides of the tire, say the 3:00 and 9:00 position it will move, but am guessing this is normal based on your reply.

Cv boots look good.

In driving around today, I could not reproduce the roar as loud as it was yesterday. It did occur, but not consistently nor as dramatically.

I think that I will wait till it happens all the time and hopefully then the cause will be more obvious. I did read on here that it could be a bearing even if there was no slop in the tire.

It reminds me of a dump trailer I have that one day no longer registered that it was connected to the truck. I probed, replaced this and that, and finally it dawned on me to pull out the breakaway switch pin on the trailer and push it back in. Voila, it worked, but I couldn't tell you why.

[DmaxMaverick]

Check those bearings periodically. Sometimes, they'll be noisy before they get loose, and they behave differently loaded vs. unloaded.

A couple other things:

Tires. Jack up (again) the wheel and give it a good spin. If the tread moves around, relative to the wheel, you may have a separation. Symptoms can vary, noise, vibration, or front end wandering or "darting" (feels like you hit a groove in the road).

If you had significant movement, left/right at the wheel, check your steering joints. Pitman, idler, tie rod and ends. Loose here can contribute to the symptoms you have.

Also check the axle nut (under the dust cap, 36mm). These are self-locking, and very high torque (130+ ft/lb). 4x4 models REQUIRE the nut to support the bearing (clamps it together). A loose nut will destroy the bearing in a hurry. GM recommends these not be reused due to loosening.

I haven't checked, but axle components may be covered under your powertrain warranty. It's free to ask you dealer.

[upandattem]

Dmax thanks again for following up. Short work week this week will give me more time to drill down and try and pin point the issue. When I do finally have a definitive cause and solution will post back a follow up.