Hey everyone. I really do hope this is not a major problem, but I noticed that the metal part of the driver side CV Axle (that goes into the differential) is wet with some kind of oil. Passenger side is clean. I also get a "groan" sound when I turn the wheel when the truck is in 4WD as soon as the "bind" starts. I think the 4WD is working because I would test it by jacking up the front left wheel and get only about 2-3" of rotation when it is in 4HI before it moves the opposite CV shaft and the driveshaft a bit. Same thing as the rear wheels. No restriction in 2HI.
Last night, for the first time, the 4WD was slow to disengage. I pressed the 2HI button and then tried to turn into a parking lot after using the 4WD. For the first couple turns, it still felt like it was in 4WD, but then it disengaged. I tried to reproduce the problem, but it worked fine. I confirmed this by looking at the actuator. The electronic parts are working fine and engage/disengage in the blink of an eye.

It has been "wet" for a while (maybe a year or two?), but when I put things together, I thought that I could have a problem here. I DO have an engine oil leak, probably through the oil pan gasket since the entire oil pan is covered in oil. I have also had both oil cooler line sets replaced in the past 2 years. It is not bad enough to have to add oil, though. Most of the oil is old. Other parts of the front axle, like the part where the actuator cable goes into the differential is also wet. I CANNOT tell if it is motor oil or gear oil. This is the repair history of items related to this:
-3 years ago, a GM dealer replaced a destroyed shift fork. Took 2 weeks over the Christmas holiday.
-About a year and a half ago, the driver's side CV shaft was replaced. I did notice that the front differential fluid leaked out when they replaced it (they showed me the car when the part I brought to them was defective and there was a drain pan under it).
-I did have both diff fluids and the transfer case checked over the summer and they said that everything was fine. I could not remove the fill plug last night to check because it was too tight.

Do I have a real problem here? Could this be differential fluid? If it is, wouldn't the axle have been destroyed just from the car moving in 2 or 4WD?

Thanks for the advice.

 

Could oil from the oil pan have reached the CV axle and I am worrying for nothing since it is not a new problem and I would have much bigger problems (noise whenever the car is moving? No 4WD?) if the diff was leaking for this long? I did notice that the axle tube that goes to the passenger side is covered in oil up until where the oil pan ends. Then it is clean and partially rusty. The ENTIRE oil pan is also covered in oil. However, as I probably said before, I rarely ever have to add oil to this truck to keep it near the full mark. I check my oil often. I wiped some of the oil off the CV axle and the differential and it was light brown and smelled like an oil product (aka It's not water), but not very strong. Didn't seem as strong as what ATF smells like with low miles on it with Lucas in it. Given the repair history of the diff and related components, could I have a major leak in the front diff that has to be dealt with before the winter?

UPDATE: I managed to finally remove the front axle fill plug and a small amount of fluid started to come out and leave a thin trail along the outside where it dripped from the bottom of the differential. Left a spot on the garage floor. This may be a dumb question, but does that mean that the axle is full and there are no problems and no leaks?
By the way, I did wipe up the axle grease with a paper towel and compared it to the suspect liquid I was talking about. They do smell different. The axle grease smelled like sewage and I couldn't keep it near my nose for more than a couple seconds. It was the same color as new motor oil, so I didn't think anything was wrong. The suspect liquid was not nearly as strong and was darker. I am beginning to think that it is just oil.