I apologize if this should be in the suspension forum, but it seems to be in the axle somewhere.

On slow turns, particularly those that are off-camber where the rear is jostled a little (such as when I enter my driveway), I hear a knocking sound from the right rear area. The sound is 1 solid knock, maybe 2 if the truck is bouncing around, that is clearly heard. It is not a series of knocks or anything that occurs based on the wheel rotation nor does it occur when driving straight or taking a long curve such as an interstate on ramp.

I've stood on the back bumper and jumped up and down and cannot reproduce the noise. However, if I grab the bed rail and push and pull the rear to get some lateral movement I can reproduce that sound. It sounds as though it's coming from the axle almost like the axle has some lateral play. Before I start tearing things apart I figured I'd check here and see if I can get enough info to at least make an educated guess as to where to start.

I think that it is unrelated, but I'll add that I recently replaced my pinion seal. It also appears as though I may be leaking a little axle fluid as the round metal shield so to speak at the outer edges of the axle is a little oily. It is not oily to the touch, but you can clearly see that at some time something oily had been there. This is present on both the driver and passenger side. I don't know if it's remnants of excessive brake cleaner or what. I do have new axle seals that I want to install soon, but I'll wait until I can isolate the knocking noise first. I recently put my pinky finger into the fill hole and can feel fluid so it doesn't seem like I am low.

Any guidance is appreciated.

Thanks,
Michael

 

Oh, i meant to add that the knocking occured before the pinion seal was replaced.

 

OK, I did some more searching and found another post with a similar issue and the answer to that guy was that this is normal and necessary. There should be some lateral play in the axle because of the c-clips. That makes total sense, however, why has this gotten worse in recent months? It seems like something is wearing out and needs servicing to restore it to its normal level of lateral play. It started almost a year ago and has been increasing in its noise level. I can hear it over the radio so it's fairly loud and if it happens in a parking lot it draws attention so it seems a little more than what would be considered normal. My truck has 156,000 miles on it so it's definitely in its senior years and starting to wear down in certain areas.