Rear Differential

[Merc2003]

I have a 2003 Mercury Mountaineer Premier AWD with the 4.6 V8. Had the rear differential replaced by a local dealer in June of 2009. The rear differential seal started to leak and there is noise coming from the rear end again. I have less than 20,000 miles on the new differential. The dealer basically told me to get f**ked. They said its past the warranty we won't help you. Any suggestions what to do if / when it goes? Are there other options for a more dependable rear end? I don't want to keep replacing this P.O.S. rear end Ford has in these vehicles. My vehicle only has 85,000 miles on it and I enjoy no car payments. Overall it has been a very good vehicle.

 

[imp]

I have a 2003 Mercury Mountaineer Premier AWD with the 4.6 V8. Had the rear differential replaced by a local dealer in June of 2009. The rear differential seal started to leak and there is noise coming from the rear end again. I have less than 20,000 miles on the new differential. The dealer basically told me to get f**ked. They said its past the warranty we won't help you. Any suggestions what to do if / when it goes? Are there other options for a more dependable rear end? I don't want to keep replacing this P.O.S. rear end Ford has in these vehicles. My vehicle only has 85,000 miles on it and I enjoy no car payments. Overall it has been a very good vehicle.

Your key statement is the last sentence-- they are very good vehicles, IMO. The rear diff. is not particularly troublesome generally, as it is adequately sized to do the job. It IS, however, aluminum-cased, and as such is not a hot-rodder's type of carrier. There are scads of Explorers/Mountaineers lying wrecked in bone-yards with considerably more miles on them than yours, and most will have still-functional rear diffs. This might be one way to solve your dilemma. It is not a particularly difficult change-out job, and you could proly find a reasonably adept repair guy needing some bread to install another...imp

 

[Merc2003]

Your key statement is the last sentence-- they are very good vehicles, IMO. The rear diff. is not particularly troublesome generally, as it is adequately sized to do the job. It IS, however, aluminum-cased, and as such is not a hot-rodder's type of carrier. There are scads of Explorers/Mountaineers lying wrecked in bone-yards with considerably more miles on them than yours, and most will have still-functional rear diffs. This might be one way to solve your dilemma. It is not a particularly difficult change-out job, and you could proly find a reasonably adept repair guy needing some bread to install another...imp

The only concern I have with a used one is you don't really know what you're getting as far as how long it may last. I figured if I have to replace it again it would be nice for it to last. I don't drive it like a sports car nor do I tow much. My mechanic said it's about a 7 hr job to replace the rear end due to the independent suspension.

 

[imp]

Understood and agreed. I suspect rebuilding the present center section cannot be done without removing it from the vehicle, as all the "guts" come out through the rear, so that route would involve even more labor than just replacement.

Should you decide to consider used, it is simple enough to manually check out the used one being considered for purchase, if it is out of the vehicle.

Rotating the pinion, in BOTH directions, by grasping by hand the companion (U-Joint) flange should produce very smooth feeling, no feel of roughness whatsoever; backlash between the gears should be barely feelable. Look for signs of wetness at the pinion flange and both axle-shaft seals. Wetness elsewhere on the case casting should be viewed as coming from a possible crack. Also most important, the gear ratio must match that of the front differential. I personally would have no qualms about installing a used unit, if it passes these tests......but, that's only me. The final decision has to rest with you. imp

 

[sethmorgan]

I personally would have no qualms about installing a used unit, if it passes these tests......but, that's only me. The final decision has to rest with you. imp

Agreed. I had a differential put in mine at 75,000 miles from a donor vehicle. Mine now has 140,000 and still no problems. I had an ABS issue that was fixed as well, as the new rear end came with ABS sensors too.

 

[ShanehSMP]

Not trying to hyjack this thread....but I'm in a similar situation

I know our rear diffs are similar to the ones in the Mustang....

Can we not used a beefier unit (see below) in our trucks?

http://www.iwerearendsonly.com/products.php?DC=FORD+8.8+Solid+axle+&+Independent

 

[mountaineer dew]

I don't want to ask on your thread but the answers would help us
Both. I have the same thing my rear end is making noises what all vehicles
Could I use the rear end from? I have the 97 mountaineer v8 awd I can get a free
Rear end from a 96 ranger 4x4

 

[imp]

In my estimation, an 8.8 Ford rear is an 8.8 Ford rear, basically all the same from a structural strength standpoint---EXCEPTING, of course, the aluminum housing job which is much less rigid, and therefore, less structurally strong.

No doubt, use of premium parts--ring & pinion, most importantly, bearings second, no cheap ****, good seals, will add life to these units. Gears are proly available at discount prices cut from inferior grade steel, maybe overseas. The BEST gears are LAPPED after heat-treatment to obtain best finish, and are coated with a special treatment to prevent scoring/scuffing during initial break-in.

The 8.8's used in 5.0L Mustangs have worked under rough useage for years sometimes. They may STILL be in use in today's Shelbys, not sure on that one. I believe properly set up, an 8.8 is pretty damn near as strong as the old 9-inch. imp

 

[mountaineer dew]

I need my rear end to match my front end because I'm awd how would I use mustang?

 

[joecrna]

Do the independent rear suspension vehicles still use the 8.8? If so, strength and longevity are not concerns. In fact our 8.8's are 31 spline units often sought after by the mustang drag guys. This differential can be "beefed Up" but it really isn't necessary in a street driven vehicle. If the center section in the independent rear vehicles is not the same as those of us with solid axle rear ends, there still haven't been many complaints of early failure.

 

[imp]

I need my rear end to match my front end because I'm awd how would I use mustang?

You could not use Mustang, as it uses a solid axle in older versions, but newer ones had independent suspension. Those might be adaptable. Casnnot tell you for sure, sorry. It IS possible that Mustang used a STEEL center section instead of aluminum. imp