Front Differential Issue

[Rahmein]

4WD was engage without ANY oil in the front diff. Took it to a mechanic and was told the bearing and everything inside had burnt up and had to either be rebuilt or replaced. I went to a wrecking yard and got a used front diff with the same exact gear ratio. My mechanic installed it for me this morning. When I took it home i noticed that 4WD High is perfectly fine but when I try to engage 4WD Low I hear a loud clunking noise when it shifts into Low. Also, I noticed its slips if I try to drive in Low. Also when I try to get out of Low you can hear the clunking noise again. Now, ever since I tested it in Low, even while in Drive, i hear a whistling coming from the front diff. It seems to get louder when I accelerate.

I already know that there is a possibility that the differential could have already been messed up before I put it in but my question is what exactly could be causing it to shift the way it is. And also why would it slip while in Low but not High?

 

[IZwack]

When in 4LO, the shifts become really harsh and jerky because of the lower gear ratio. From your description, the transfer case is working just fine.

As for the whistling, could be anything at this point-- even the intake (which is known for "whistling").

Try not to use 4LO again, 99.999% of the time, its not needed.

 

[Rahmein]

well i do have a k&n air intake which does whistle but this is definitely coming from the front diff. I'm not sure whether it was whistling before i tried to put in low and got the loud clunk, or after. I'm hoping the one i bought is not messed up. I'm going to take it to my mechanic today and let you know what he comes up with.