1997 Ford Explorer Transfer Case

SK8THETILT

MEMBER
1997 FORD EXPLORER
6 CYL
4WD
AUTOMATIC
125,000 MILES

Last year during winter season I noticed my four wheel drive wasn't helping me out in snow conditions. I took it to a mechanic and they put it on a heist and tried to engage the 4 wheel drive. At driving speed (10-40) it engaged sporadicly and disengaged just as poorly. We couldn't make a connection as to why or when this happens. It almost never engaged into low from a neutral position. They replaced some module and I thought it worked (probably placebo effect). I used 4 low to get out of a muddy situation and when it locked in it made a grinding noise before it finally did. But now driving it in dry weather on a road I definitely feel the gear ratio change but when I turn where there used to be a pulling from the front tires locking in there insn't. How do I know if it really in 4wd? I recently changed the transfer case fluid (which wasn't much) and replaced the vss on it. I'm told that cleaning the transfer case pump solves almost every 4wd problem is there any truth to this? Thanks.

1 Reply

JAMES W.

MECHANIC
2,394 POSTS

The fourwheel drive " on the fly" system will engage, via a clutch pack, when the computer system senses one output shaft is turning faster than the other. This engagement will only last a few seconds and drops out automatically. Fourwheel drive "lock" is an actual gear to gear engagement that is controlled by 2 motors, one for 4wheel in/out-one for high/low. The "lock" position should not engage or be engaged above 4 mph ie. Almost stopped. If it does try to engage above 4 mph, the gears in the transfer case will not have sufficient time to fully engage and they will grind or not mesh at all. If this has been allowed to happen continuosly, the mesh side of the gears may have become worn or chewed up which further restricts their ability to mesh. Bottom line, assuming the shift module has already been replaced, I would look at the internals of the TCase or consider replacing it.
The pump lubricates all of the components on the TC main shaft. If this pump is restricted or has failed, it could cause the problems you have described. But, usually by the time you find this out, the internal damage has already been done. In these TC's the pickup tube for the pump has been known to split, causing little or no fluid supply to the main shaft.