Transfer case not working properly

UNIMATRIX13

MEMBER
1998 FORD EXPEDITION
5.4L
V8
4WD
AUTOMATIC
204,000 MILES

Hello everybody, I hate to ask questions but I've searched all over and can't seem to find an answer. As stated, in 2wd, when I can get it to go into 2wd, I can drive for about a mile and it pops out of 2wd and grinds like crazy. I stop, shut off the engine, put it in park, switch to 4lo, start it back up, put it in gear and it drops in with a nice clunk. Drives just fine in 4lo. Before you ask, I keep it 2nd, below 10 miles an hour, and off the dry pavement as much as possible.
So in the beginning it was just the 4wd was not engaging. Lights came on but no engagement. I made a smoke machine and found some vacuum leaks, fixed those but didn't fix the problem. It did run better though so that's good. I replaced the transfer case shift motor with a new one transferring all the wires correctly, but didn't fix it.
Let me back up real quick, this is the vehicle my daughter drives and after explicitly telling her to never put it in 4lo, she did it one night because she was trying to turn around on the icy street. Don't get me started. That was the start of the problem. After it going into 2wd just fine by using the switch, it left her on the side of the highway the next day with the current issue. Had it towed home on a flatbed. I was able to push it, jump in and popped it into drive getting it back into 2wd. Since then it has left her on the side of road 2 more times and now it will only work in 4lo.
I drained and refilled the transfer case oil thinking it might be low, didn't fix it.
Appear to have vacuum at all the proper places. Seems like the issue is in the transfer case to me. I assume that's where the grinding is coming from. I'm considering removing the transfer case shift motor, manually moving it to 2wd, and taking it for a spin. Anyone see a problem with that? I'm concerned that if it pops out again though I can't get it back home.
Sorry so long, trying to be thorough.

5 Replies

ASEMASTER6371

MECHANIC
52,797 POSTS

Good morning,

I believe you have a transfer case issue with an internal failure. Something happened when your daughter had it in 4 wheel low when she was stuck on the ice. There most likely is more to that story.

I believe you will be replacing the transfer case with either a rebuilt unit or a used one.I attached the procedure for you below/

Roy

1. Warning: the electrical power to the air suspension system must be shut off prior to hoisting, jacking or towing an air suspension vehicle. This can be accomplished by turning off the air suspension switch located in the rh kick panel area. Failure to do so can result in unexpected inflation or deflation of the air springs, which can result in shifting of the vehicle during these operations.

Raise and support the vehicle.

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2. NOTE: Drain the transfer case if disassembly is required.

Drain the transfer case.
- Remove the drain plug.

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3. NOTE: To maintain initial driveshaft balance, index-mark the rear driveshaft yoke and axle flange so they can be installed in their original positions.

Remove the rear driveshaft.
1 Remove the four bolts.
2 Remove the rear driveshaft.

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4. Remove the front driveshaft shield.
1 Remove the nuts.
2 Remove the front driveshaft shield.
5. Remove the No. 3 and 4 crossmembers.

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6. Disconnect the front driveshaft.
1 Remove the four front driveshaft flange bolts.
2 Disconnect the front driveshaft.
7. Remove the torsion bars and rear torsion bar support.

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8. Remove the transfer case skid plate.
1 Remove the four bolts (two each side).
2 Remove the transfer case skid plate.

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9. Disconnect the Vehicle Speed Sensor (VSS) electrical connector.

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10. Disconnect the electric shift motor electrical connector.
11. Support the transfer case.
- Use a hi-lift jack.
- Secure the transfer case to the jack with a safety strap.

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12. Remove the six transfer case to transmission bolts (three each side).
13. Lower the transfer case.

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