Transfer Case Question | Ford Explorer Forums - Serious Explorations

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Transfer Case Question


Well-Known Member
April 11, 2009
Reaction score
City, State
N. Andover Massachusetts
Year, Model & Trim Level
99 Mercury Mountaineer
Thank you for taking the time to read this thread.
I have a 1999 Mercury Mountaineer with a 5.0L engine and auto trans.

I think my transfer case is getty ready to fry up on me.

When I was at the junk yard poking around I stumbled across a 1999 Explorer.

Almost everything on a Mountaineer is interchangeable within certain years of Explorers.
This particular 1999 Explorer has a 4.0L six cyl. engine w/auto trans.

Could one of you "Pro's" tell me if the transfer case is interchangeable. I am wondering about this because of the torque of a 4.0L six cyl. versus my 5.0L eight cyl.
Any information will be much appreciated.
Thank you.

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no, that transfer case will not work, you will need an awd transfer case out of another v8 explorer/mountaineer. What leads you to believe yours is about to give out?

Hi Techieman,
Thank you for your reply to my post, I appreciate it.

When I back up or pull forward (especially with the wheels turned) I get a chattering/vibration. It goes away when I get moving and the wheels straighten out.

One day with my wheels straight I drove by a row of side by side garages and I could hear a random "thump" noise going forward and a clicking noise in reverse as I slowly drove by.

At 170,000 miles I replaced the front "DANA" drive shaft.
A few months later @ 174,000 miles I noticed this strange chattering/vibration.

Any information will be very much appreciated.
Thank you.

Welcome Rick, it is hard to diagnose the AWD TC, many other parts can have similar symptoms. What is the condition of the tires, are they identical all around? AWD's have to have the same diameter at all four tires.

I'd have a harder look at the front suspension and axles/hubs up there first. You are listening and hunting for the problem, that is a great first step to finding it ahead of time. Regards,

The quick simple way to pin this one down will be to drop the front shaft and see if the problem persists. If it goes away, then I would agree that the viscous coupling inside the t-case is likely going bad. If the problem persists, then I'd be looking at the rear differential (especially if it's a limited slip).

Out of curiosity, did you have the rear diff serviced at the same time as replacing the front shaft?


Hi Joe,
Thank you for your reply...I appreciate it.
I have been lazy and did not change the rear differential lube at all.
The 10 - 20 degree winter weather here made the front "DANA" driveshaft a rush a get it done job.

I am going to disconnect the front drive like you advised and see what is going on.
I am going to inspect the differential lube to see if I can see any signs of problems... it is way over due for a change.
Thank you Joe.