(Sorry ahead of time for the long read, I believe in trying to give as much info as possible.)

vehicle: 98 Explorer XLT 4.0 4wd (4405 T/C)

I need a little help finding this problem. I havent owned this truck for very long and this problem has existed since I got it. I cant quite pin it down and was hoping someone with more drivetrain experience could help me.


In 4WD mode, under load, such as going up an incline or at low speeds with the steering way over to either direction, There is a very hard clunk accompanied by a sort of a hollow metallic ping. This happens under extreme load (very steep incline like my driveway) in "4WD Auto" mode, but it happens more obviously, and regularly in 4WD high/lo modes, and doesnt require as much load to cause it. It does NOT clunk under very light load like flat ground/minimal throttle.

I figured it was the spiders in the front diff, so I replaced the front diff with a low mile one. While I had them both on the bench I compared them. They were the same in all ways. I put the new one in anyway but as I suspected by that point, no fix. no improvement, problem did not get worse.

When I had the front drive apart I inspected the half shafts. The boots were still intact and the joints felt ok. I obviously couldnt put them under enough stress to see what they really do under load, but they dont make noise turning or at speed under any other conditions.


Ive recently had my transfer case apart (while repairing my transmission) and it looked good inside. The only that concerned me at all was it seemed the chain was kind of loose, but I didnt see any signs that it was jumping teeth.



Questions:
Could the CV's still be the problem?
I didnt want to remove the boot clamps to look at the joints, and I didnt wan to just throw $100 worth of axles at it at this point (I already feel stupid enough for the front carrier).
Could the driveshaft be the problem?
I dont feel play in it and the front U-joint felt fine but the rear joint is the cup style mount. Do those fail? what about the slip yoke? maybe the splines?


Im almost ready to just go put her in low and romp on her until something fails completely to find the issue, but this 'ol rig has 300K miles on her, and I dont want to tear something else up.


Suggestions?

 

decided to just swap in a junkyard T/C and go from there.

 

NOOOOOOO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! its the cv axles the money you will waste on the t-case u can buy new cv axels my eddie bauer explorer did this its the joints in the rubber boots after a period of time the grease wears out thats whats wrong

 

Already picked up a t/c for $125. If it turns out to be the halfshafts no big deal to do those too.

 

awe man i wish i could have stopped you atleast you have a back up t-case but i suggest you rebuild that one throw it in then rebuild the other one thats what im gdoing atm i have a 83 bronce that was givin to me and i have a BG 1345 or 1346 t-case out of a parts truck im rebuilding atm and man is it fun and easy lol

 

Im going to bet you $10 that its the T/C anyway.

 

where do u live cause ill take that bet but i want to be there when we find out lol

 

probably not worth the drive to Oregon, lol

 

probly not but after you do the t-case i want to see a video and hear it if it works ill send you a monmey order if it dont and the cv axles work then you send me one and if neither works you can keep both halves of the broken part how does that sound LMFAO

 

So, I would have actually sent you $10 in the mail if you had been right, but thankfully Thats not the case!

WOOT! I fixed it with the junkyard T/C.

It was fairly obvious to me after I took one of the hall sensors out and checked the tension on the chain that the new case was in FAR better shape. Just with my finger through the hole I could slap the chain in the old case up enough to hit to the outer case. The chain in the new case was FAR FAR tighter.

The whole swap took me no more than 3 hours start to finish and with that, I can say my $500 explorer no longer has an major mechanical issues. (well, ok aside from a little timing chain noise when cold. But what do you expect with 303K miles).

Total investment in the rig so far: $900
Im stoked!


edit: I'll do a post mortem on the old T/C here in a day or two, and take some pictures of it inside. I may still rebuild it and resell it to recoup some of my investment.
p.s. This was the cheaper XL24 4405 unit.

 

damn when do you want me to send you the ten bucks

 

naa dude, Im just happy I was right and didnt waste the cash for stuff I didnt need....again!

 

lol ok im good for it of you change your mind lol

 

I had the same clunking noise in 4WD going up a hill and it turned out to be that chain was too loose like yours. They put a new chain on ($200 just for the chain) and no more clunking. It was a NASTY sound!