I think I'm stuck in 4wd

[FNFAL]

Hey guys, I would appreciate your input here. I just picked my '99 sport up from the mechanic. He replaced the front left wheel bearing. While driving home I noticed wheel chatter when turning, felt like it was in 4wd.

I can hear it clunk into 4lo and and back out when I switch it. So the switch and dash lights seems to be working. The wheel chatter is not always the full on hard like when its switched to 4hi on dry pavement, except for a couple times. Usually just notice some grabbing and vibration.

I tried disconnecting the battery to reset the computer, still chatters. Tried unplugging the harness to the transfer case shift motor, still chatters.

So does that mean it's a mechanical issue if the problem persists with the harness unplugged? Something came apart in the transfer case?

The wheel bearing replacement would not be involved in this would it? Seems odd that is when the problem started.

 

[IZwack]

Remove the front driveshaft and see if it still exhibits the same behavior. If not, then the transfer case is likely stuck in 4wd as you stated. If the behavior still persists, then this is probably not a 4wd issue.

 

[FNFAL]

Thanks for the tips. I tried your suggestion and was unable to free the bolts on the front end, the rear bolts I was able to loosen. The torx socket was just starting to tweak, probably would have broke, it needs heat or an impact gun probably.

I did take it for another short test drive today. On a wash-boarded gravel road it was all but uncontrollable at anything more than 20mph. I drive that road everyday and normally go 40mph with no problem. The front end was bouncing around like crazy. Shifting between "auto" to "4HI" and making tight turns in the gravel i could detect no difference in handling. Felt like it was in 4wd. It went into and back out of 4LO without issue.

So anyway I decided that even if I got the shaft off and diagnosed the problem further I really don't have the time to work on it. Or the skills, or a heated garage, and it's cold out!

I'm taking it back to the shop tomorrow. I'll post back with the resolution. thanks!

 

[rickybobby]

spounds like maybe they damaged a wheel speed sensor. If the sensor on the new bearing is reading slower than the others it will stay in 4wd

 

[FNFAL]

Hey thanks! I will ask them about the sensor.

Would a bad front speed sensor still cause the 4wd to engage even with the 16 pin harness disconnected from the transfer case shift motor? Because yesterday when I was messing with it, during the test drive with the harness unplugged, it still behaved as if it were in 4wd.

 

[my98nnj]

Air in the power steering, very typical after work is performed on the front end.
Moving slowly, turn the steering lock to lock several times to purge the ps system.
That should fix it.

 

[FNFAL]

Thanks for the steering idea, wish it were that easy but it turns out to be the transfer case.

I dropped the Explorer off at the the shop on Sunday afternoon. He looked at it today, said he put it on the lift, engine off, spin the wheels and it's in 4wd.

So he is going to open the case up and take a look, he suspects broken plates or discs rather than broken chains?

He said he rebuilt one last week and the cost ended up being $600. Sound reasonable?

 

[FNFAL]

So I didn't need a transfer case rebuild after all. Shop called me today and said they drained the case and the fluid was really black and nasty but had no metal shavings in it. So he filled it with fresh fluid and the problems disappeared!

This fluid change also had the added benefit of fixing my overdrive that would keep kicking in out at highway speeds. Now it happily rides along at 2000rpm instead of sea sawing up and down from 2.5k to 2k. And the very slight shimmy it had on smooth highways, that I thought was a bad tire, is gone also. I guess the drag of the 4wd kicking in caused both of those problems.

My Ex has 140k miles on it, I put 60k on it, bought it used with 80k. I never changed the transfer case fluid. It was probably the original stuff in there. I know, I'm an idiot, but lesson learned! Change your fluids!