Hello. I've been hearing a hum under my truck for a while now. I thought it was tire noise but it seems to be getting louder. While i was under it changing the oil I noticed some oil where the axle goes into the front diff. See the pic. This is on the right side.



Not sure if that can cause the hum. I also noticed the front driveshaft has play in it. I can rotate it about a quarter inch either way.

Should i replace the axle or is it internal to the diff tube it's in? The boots are fine it's only leaking in that one spot.

 

Anyone? Bueller...Bueller?

 

Just your seal leaking. If it is not major I wouldn't worry about it. Go ahead and check the diff fluid level though. Should be able to open the fill plug and touch the fluid with your finger.

Driveshaft will have movement. Sounds like the normal amount.

 

Thanks, I checked the level. A little trickles out when I take off the plug, so that's OK.

Still, the hum is getting louder. Fluid levels in the tranny, transfer case and front diff are all OK; no burnt smell or discoloration. The U joint on the front driveshaft is looking a little rusty, can that cause it? Is there a way to check the joint at the rear of the shaft?

 

I forgot to follow up on this. I took it to a mechanic, one I've gone to many times before with an old Kia I had. A road test and inspection later I found out the hum was due to me not rotating my tires in the two years I've had the truck. D'OH!

Didn't cost anything and they performed an inspection as well. The mech was surprised at how good of shape it's in for being an 05.

Anyhow, rotate your tires regularly or they will make serious noise!