Extremely Hard Clunking When turning on any surface in 4hi or 4lo

[mcfixstuff]

I've been just not using 4x4, so it hasn't been that big of an issue, but with the weather getting colder, I'm gonna want to off-road and camp, which will requite my 4hi and 4lo. It engages fine, no issue, goes into 4hi, and 4lo, then back to 4hi no issues. Going in a straight line...no issues, reversing....no issues. Any time I make any turn on any surface, slippery, or solid, it clunks extremely bad, like something broke, but then it keeps working. Another issue I have is it having a tough time going back into 2hi. I'll reverse, and then when I start going forward, it'll make a really rough grinding noise, like its still making contact with the splines on the auto hub. Sometimes I can get it to eventually come out 4wd by constantly engaging and disengaging it, going into reverse and forward, but other time's I just cant, and have to drive and turn the wheels sharply until I hear one more extremely violent clunk, then it's finally out of 4wd.
This makes my 4wd feature essentially useless, and a big pain in the ass.
I've taken off the hubs and cleaned everything with brake cleaner, then had everything sit in a tub of ATF overnight, and reinstalled everything, but it made zero difference. The inside of the hubs look completely fine. I'm 99% sure the owners before me never used the 4wd function on it. I have also changed the fluid in the front differential, and replaced the front driveshaft u-joints.
I really don't have the money to get manual locking hubs, and I don't off-road serious enough to warrant them. I use my 4wd function only if I'm stuck, or on loose terrain, I don't really do crawling or anything with it.
It also didn't do this when I first got the Explorer.

Any tips on how to diagnose the issue, or is there anyone who has had this issue, and feels like they know what the issue is?

 

[RangerX]

Auto hubs don’t last forever, and most died 10-20 years ago.
That said, a possible cause is driving in 4wd on pavement. You will get binding and popping of the driveline, especially with slow sharp turns which you describe doing to try to get it out of 4wd.
Try doing the procedure on grass, dirt, etc, and see if that helps. Wet pavement is not good enough, IMO.

 

[mcfixstuff]

Auto hubs don’t last forever, and most died 10-20 years ago.
That said, a possible cause is driving in 4wd on pavement. You will get binding and popping of the driveline, especially with slow sharp turns which you describe doing to try to get it out of 4wd.
Try doing the procedure on grass, dirt, etc, and see if that helps. Wet pavement is not good enough, IMO.

This happens in mud

 

[~X~]

Have you checked your axle U joints? Still sounds like hubs, theres a 10mm bearing in there that wears out. I'd still look at the axle U joints.

 

[RangerX]

Welp, then it’s the hubs.

 

[mcfixstuff]

Oh yep. One side is definitely ****ed, however this isn't the side that's making noise. This side wont engage, and is quiet.

This side however would only grind when I put it into 4wd.

I think I'll just save up for manual hubs because they honestly don't look that expensive anymore. Do I just buy the manual hubs off rock auto for $100 a piece?
RockAuto part I'm referring to

 

[92exp4x4]

Oh yep. One side is definitely ****ed, however this isn't the side that's making noise. This side wont engage, and is quiet.
View attachment 425180View attachment 425181
This side however would only grind when I put it into 4wd.
View attachment 425184

I think I'll just save up for manual hubs because they honestly don't look that expensive anymore. Do I just buy the manual hubs off rock auto for $100 a piece?
RockAuto part I'm referring to View attachment 425182 View attachment 425183

I recently bought a set of hubs off eBay for $90. They included the spindle nut conversion but i found the threads to be weird and i didn't want to damage the spindles. I ordered mile marker spindle nut kit as well as i wasn't sure if the hubs came with the nuts or not. Im glad i did, It fit perfectly. The whole thing cost about $165.

The hubs seem to be half way decent quality. Certainly good enough for the use you described. I just did this a couple weeks ago.

 

[mcfixstuff]

I recently bought a set of hubs off eBay for $90. They included the spindle nut conversion but i found the threads to be weird and i didn't want to damage the spindles. I ordered mile marker spindle nut kit as well as i wasn't sure if the hubs came with the nuts or not. Im glad i did, It fit perfectly. The whole thing cost about $165.

The hubs seem to be half way decent quality. Certainly good enough for the use you described. I just did this a couple weeks ago.

I actually bought a set of mile marker's off amazon. They had a returned set of hubs that I was able to get for like $40 off. In total, I paid $135 for everything. Fixed my issues

 

[92exp4x4]

I actually bought a set of mile marker's off amazon. They had a returned set of hubs that I was able to get for like $40 off. In total, I paid $135 for everything. Fixed my issues

Even better! Im glad it fixed your problem. Mine weren't bad, but I suspected the u joints to be seizing up. I wanted the manuals so i could lock in the axle and let it rotate while driving around normal to loosen up the joints. I had a drive line noise issue and minor steering feedback. It wound up being inner wheel bearings on both sides.