Mysterious grease around front-passenger axle (2002, 4WD, 2-Door)
 

I was doing some routine checks under my vehicle and I noticed there is some serious grease build up around the front-passenger axle.
I have some comparison photo between the left and right side of my front axle to show.

I also noticed that the front differential is also slowly dripping grease. I rarely use 4WD if not at all, but I have recently engaged it a couple weeks ago.
I'll engage 4WD from time to time off the pavement just to get the gear turning once in a while so nothing could seize up.

I'm still relatively new to this and I'm not sure what kind of maintance a 4WD system needs.

Front Passenger
https://cimg6.ibsrv.net/gimg/blazerf...8358fb1efe.jpg


Front Driver
https://cimg0.ibsrv.net/gimg/blazerf...93f6a0b4b7.jpg

Front Differential
https://cimg1.ibsrv.net/gimg/blazerf...9b05f97f50.jpg

The green grease found in the picture of the passenger side very well could be CV shaft grease leaking from a tear in the boot. The grease used in the CV shafts usually is green in color while other chassis grease is red or dark gray (depending on the preferences of the person squeezing the grease gun). The picture on the driver side looks more like you may have a slow leak in front differential output seal that has caused gear oil to sling out & collect dirt. Not necessarily an issue requiring immediate service, but you'll at least want to check the front diff level.

Your last picture could be a leak in the front differential engagement bracket, but also could be a leaking oil cooler line which is located right above the front differential; a leaking oil cooler line could also be the cause of the dirt/oil buildup on and around the driver CV shaft as well. Again, not necessarily something that requires immediate service if the levels of both the engine oil & front differential do not drop appreciably over time and/or there isn't a oil slick under the truck after it sits.

Ditto on what swartlkk said. To fix the boot, you can get nice new neoprene boot kits. I replaced the inner boot on one of my front axles and it was not too bad at all. What was the only hassle was getting to it because you have to take the front suspension partly apart to get the axle out. If you are already in there and are mechanically inclined it would be a good time to replace the output shaft seal on the drivers side. When I did my output shaft seal on the drivers side I also replaced the output bearing.