Fixing AWD, Putting Driveshaft back in.

[Ahorvat46]

I bought a used 2004 Mercury Mountaineer 4.0 AWD, at the time I didn't realize it was so common to remove the front driveshaft on these. A couple months later I found out the AWD Mountaineer I had just bought is RWD. The front drive shaft is missing. At the time, when i bought it, the car did not have 4 matching tires. I then replaced all four tires with new matching ones and replaced all four wheel bearings. Over the next few days I drove the car from Kentucky to California and back so it runs quite well. It still sucks that I do not have AWD, I suspect the previous owner removed the front drive shaft because all four tires did not match, this could be an easy fix, However, I am afraid if i put a new driveshaft in I will find out the viscous coupling is bad and I need a new transfer case or the front driveshaft is bad. Does anyone have experience fixing this problem? I am driving to Big Bend National Park in Texas next week and would really like AWD. Please help, thanks.

 

[lincolnshibuya]

there's a reason why it was taken out in the first place, putting it back without knowing what it was is like playing russian roulette.

it could be front differential and/or transfer case issue.

 

[Ahorvat46]

Do you have any experience with this? is there any way to determine which one is the problem?
It would be very fortunate if tire size alone was the issue and the previous owner removed the driveshaft before the other components were damaged.

 

[extra-medium]

I second the probability with a front differential or transfer case issue. It would be too hard to blindly diagnose without getting into either of them and seeing if they are all there and don't have any issues.

 

[lincolnshibuya]

Do you have any experience with this? is there any way to determine which one is the problem?
It would be very fortunate if tire size alone was the issue and the previous owner removed the driveshaft before the other components were damaged.

No experience on buying a 4x4 with missing front driveshaft (all the 4x4/AWD vehicles I have has working front drive shaft.. mounty,jeep,navigator and bmw) but I could tell if the front is binding or transfer case is shot.

One of the main reasons why the transfer case is shot (or the 4x4) is because of uneven tire size or leaks (low fluid), putting in new tires doesn't fix it (unless the PO just decided that he'll just buy rear tires and do with RWD).

You could install the driveshaft back and test to see where's the issue. Here's a reference for you, it's common for AWD viscous coupler to fail on Mountys.. http://www.explorerforum.com/forums...e-and-you-on-viscous-couplings-bw4404.225515/

 

[Ahorvat46]

Thanks for the link that pretty helpful, it's most likely the cause but I'm trying to be optimistic. do you think I could tell if the front diff is binding by manually turning it? I could also open it pretty easily, what should I look for inside? missing teeth or cracked parts?

 

[lincolnshibuya]

drain the oil on the front and check the condition, if there are large metal particles maybe time to replace or need to open the cover and visually check the gears. put fresh fluid in if you find it ok. Chances are it's the transfer case that locked up and you will be hearing a lot of noise when it runs. just put it in jackstands first, in neutral and rotate the tires manually and check for noise (or if you are confident enough, start the engine and put in "D" but be safe).

 

[CDW6212R]

The issue could be anything mentioned, but installing a front driveshaft should not be a bad thing.

The real question immediately should be how much fluid is in each, the front diff, and the TC, plus the condition of them. Without enough gear oil in front the differential is likely ruined, whether that was a problem before or not.

I bought a 98 AWD Limited last year, with a mild growl in the front(my guess a front hub). I knew it had no drive shaft, and also hoped it hadn't hurt the TC. It turned out that one of the front axle seals leaked out most of the gear oil, the differential was shot. My TC had black fluid in it, obviously that was neglected too.

Check your fluids first, know what level they are now and replaced them. Do the front shaft, it needs it and if the tires are equal, will cause no harm. If the TC or diff is bad, you need to know it so you can work on it. Good luck,

 

[Ahorvat46]

I did have a front axle leaking, which I fixed but there's no telling how long that was empty, I had at least put 4K miles on it before I realized it was leaking. I'll start with opening up the front diff then move to the TC. thanks for the help.

 

[CDW6212R]

The whole front right side under my engine bay was covered completely with grime. I took the whole set of parts out of mine to swap with my known good Mountaineer parts. I was surprised when I tipped the front housing on it's end, only about six ounces of grease came out.

I don't know if you can get the front cover off from a 2002+ model, but you can remove the fill plug and see how much it takes to fill it up . If it doesn't need more than about 24 ounces or so, the differential may be fine. I think most take about 1.5 quarts from empty. You have to remove a wheel to get access to the fill plug on the side.

The AWD is easy to R&R the fluid, one plug for the drain, and one for the fill. That's about a 10 minute job given a hand pump made for quart bottles.