03' XLS 2wd 'popping' noise from rear when towing

[PC]

Hi all!

When I tow my 6x12 trailer (tongue weight approx 250#) I am getting a popping sound coming from the rear end. The noise only shows itself when towing, so it certainly has something do do with the downward pressure being applied from the trailer weight.

I haven't noticed it at hwy speeds. I hear it from starts and low speed driving.... it does it both in a straight line and turns. And whenever I apply the brakes the noise immediately stops. Any suggestions as to where to start hunting? I've pulled the wheels and checked the brake assemblies and they check out okay although I have not checked the e-brake assembly.

Thanks!

Edit: just looked and have axle code 45. 3.55 non LSD.

 

[PC]

I swapped the rear u joint today in hopes it was the culprit. The OEM didn't look too bad, but it was showing wear (97k miles), so it got swapped. I also changed the diff lube.

I'll know on Sunday if this was the culprit as I have some towing to do.....

 

[storlied]

CV axle?

 

[clarks2001]

CV Axle would be my guess. My front passenger side pops when its in 4 wheel drive (so now dont put it in 4 wheel drive) and it lightly pops in 2 wheel drive. I need to search for a write up on replacing the front CV axle now... hmmm. lol