Transfer case or Front DS?

First to let everyone know I have a 2003 Ford Explorer 4.0L 4dr. I have a borg warner 4411 transfer case 2 speed elec shift. The transfer case is a reman unit from Transmission Authority which is a company that sells reman units through rock auto. The transfer case is a little under a year old so its leading me to believe that it is not the problem. The problem I am having is when only in 4WD and when you are turning the wheels does a very loud cracking noise/banging noise happen. This happened on a very slippery surface so it is not axle bind or w/e you call it. I thought maybe it was the CV axles so I replaced them since they were under the lifetime warranty. Turns out that was not the problem. Next I checked the front differential. I thought maybe something happened with the ring and pinion its been about 6 months since i had 4.11's installed. Turns out everything checked out 100% in there. Next I pulled the front driveshaft. No more cracking/banging noise in 4wd but I saw that coming since it seems like its only under a load with the front tires. I checked the propeller joint it seems ok i guess? I really don't know how to tell if its bad it seemed fine. No cracked boot and grease inside no contamination. I spun the transfer case flange that powers the front and it spins freely in 2wd. Once i put it in 4wd it locks up since the rear DS is not moving but then if i rotate the opposite direction it will unlock then lock up so i'm wondering is that normal? could the transfer case be at fault here? How do i diagnose this 4wd works fine just makes that crazy loud noise sounds like something is going to break! Could it be the front driveshaft propeller joint? I eliminated the front axles and diff what else could it be?

did you check the hubs?

The hubs have no play in them and make no noise when turned by hand. I checked them when taking the axles out.

I would drain the fluid out of the transfer case into a clean container and check for any metal. It's only a few qts of fluid. If that checks out good I would look at the front driveshaft a little more.

Or the front diff

Ok I will check transfercase fluid when I get home. The front diff has already been checked. I drained it and spun the wheels to check the ring and pinion. All looks fine.

Changed the fluid in the transfer case and the old fluid looked good. No bits of metal in there. Had a little bit of metallic dust but nothing out of the ordinary. That was the 2nd drain I have done since I got the transfer case. First one was the break in procedure a while ago then I just did that drain right now.

Ok so I changed the cv joint and the ujoint in the front driveshaft as they were very loose. Turns out the problem still persists. I think the next step is to pull the transfercase as I can't see it being anything else. I did notice playing around in 4wd low on loose gravel that the truck bucks and jerks when accelerating as if the front driveshaft is intermittently catching up the rear driveshaft. Is it correct that when locked in 4x4 the front is suppose to spin the same speed as the rear driveshaft? It would make sense that something is broken inside of it because the only time it would make that loud cracking noise is if the front was moving at a different speed that the back ex. around a turn. Is there a specific part that locks the front and rear driveshaft together in the transfercase? someone said it could be a range fork? Not sure what they even do. Any help would be appreciated Thank You

Have you tried it without front shaft installed?

Yeah there's no symptoms without the front driveshaft. Makes sense because there is no load on it without it. So it was either the front driveshaft was binding or something in the TC. I'm going to have to pull the transfercase and open it up.

Yesterday I went on the beach with the truck. The noise is so loud that it turns heads! I had my friend stick his head near the bottom of the truck and the noise is in fact coming from the middle near the transfercase. Nowhere near the front is it making the noise. So I called the company I got the transfer-case from, ETE Reman. I told them the problem that I am having and surprisingly they are sending me a new unit no questions asked. I will report back once the new one is in.

So I put the new transfer case in and problem still persists....going to pull the front differential out and give it another look. Not sure what else this could be. Also getting a squeaking that gets worse with speed and is noticeable loud. Seems to get louder the longer you drive the truck. Greased all u joints so it's not them. Any other ideas would be greatly appreciated.

If your transfer case has hall effect sensors, make sure they are evenly pressed in the case. Tap gently all round the edge with a small drift. I rebuilt my transfer case and it made a horrendous noise. Read on this forum to make sure they were all the way in, and no more noise. Couldn't believe it!!!