After replacing front differential vehicle is pulling to the left

PINKBRILLOPAD

MEMBER
2002 MERCURY MOUNTAINEER
V8
AWD
AUTOMATIC
85,000 MILES

I have just replace the front differential. One month ago, I had two tires replaced and an oil change on a Saturday, and while I was on the road later that day she broke down on me. Evidently there was a gear oil leak and when too much had leaked the front differential locked up. Now that we have swapped it out, my car is pulling to the left. I took it in to check the alignment but was told that was not the problem, I was told it had something to do with the differential or possibly an axle. I am not sure if it is relevant, but I want to mention that the two front tires had been replaced and were slightly wider than the rear tires. Once I replaced the differential, I rotated the wider tires to the rear and now my car is pulling to the left and it feels like the AWD is struggling. Not to mention I am getting six to seven MPG now. Also, when I make a sharp left turn there is a pop, or what sound likes like possibly a bad bearing or ball joint. Not sure. Can you help?

6 Replies

ADAMWHITMAN

MEMBER
1 POST

I am not an expert but have had front differential problems lately on the same 2002 Mountaineer v8 AWD model (mine is the earliest model). The first thing I would do is change the two old tires with the exact same brand and model tire right away. I have been told these differentials are so sensitive that simply having slight diameter differences can really mess with the differentials. Make sure that circumference of the tires is very close and that may solve the pulling problem.

That pop that you are hearing may be what I just had to replace on my rig which was two of the front differential carrier bushings (the metal encased rubber bushings that mount the differential to the frame. You can get under the car and look at the bushings. It was pretty obvious they were shot in mine but I put a jack under the diff and pushed it up to make sure that the popping noise was coming from that. The two I had to replace were on the drivers side. Here are the part #s: F67Z3A443AA (for the lower one towards the back) and 1L2Z3A443AA (for the upper front) again these were both on the drivers side. I have to remove the entire differential (this involved removing the tires, brakes, brake discs, ABS sensors, pulling the tie rod ends and the upper control arms using a pit-man puller, removing the stabilizer bar, removing the CV joints, disconnecting the driveshaft from the differential, and finally pulling the bolts mounting the differential). I then cut the flared ends off the bushings using a hack saw, and pressed them out and in using a ball joint press I borrowed from O'Reilly Auto Parts (I had to use an 1 1/4 socket to drive out the bushings). Do not confuse the parts when installing them. They are very difficult to press out. Believe me I know. I found the parts on eBay for about $64.00. Just look up the part number. The place I found on eBay showed them only compatible with Explorers, but as I am sure you know they are the same. You will want to drain the differential oil first and that stuff is pretty pricey.

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Friday, February 28th, 2014 AT 1:27 PM

FRMOORE

MEMBER
1 POST
2002 MERCURY MOUNTAINEER
3.8L
V6
AWD
AUTOMATIC
170,000 MILES

I took my mountaineer to a mechanic he said I needed a front differential so I bought one from his scrap yard and paid him to put it on. Two weeks later it went out again he said the transfer case is causing the clips to come out the front differential and I now need a transfer case and its pointless to replace the front diff again without the transfer case even though he said it was the front differential that was messed up and it had a warranty. Can the transfer case cause the front diff to go out and shouldn't he have to refund my money if nothing is fixed.

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Monday, November 19th, 2018 AT 7:29 PM (Merged)

CARADIODOC

MECHANIC
33,912 POSTS

Absolutely. Mechanics like working for free, as I'm sure you do. Try getting a refund from a doctor when they don't cure you on the first visit. For some reason, mechanics are held to higher standards than doctors.

The other problem is supplying your own parts. I understand the reason, which is to save money, but that's like bringing your own food to a restaurant and asking them to cook it for you. When the shop supplies the parts, at a small markup, they assume the responsibility if they prove to be defective. When you provide the parts, the shop can legitimately charge you again to replace them the second time. The parts markup they charge goes, in part, to cover the mechanic's labor when he has to do a job over again when it wasn't his fault.

You didn't say what was wrong with the original differential or why it needed to be replaced, so at this point I can only offer that there are different gear ratios available, and you have to find a replacement differential with the same ratio as the rear unit. Assuming you did that, we would need to analyze the original failure, which isn't common at the mileage you listed, to figure out if something is causing it. One thing to consider is if there's a tire on the vehicle that's has a different outer circumference than the rest. That will put a lot of stress on the transfer case, but only when it's in four-wheel-drive.

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Monday, November 19th, 2018 AT 7:29 PM (Merged)

SUPERSHAFTS

MEMBER
9 POSTS

What exactly is he claiming the tcase is breaking at the front diff.

What clip?

If you have a awd tcase and the vc is locked up, then what can happen is in tight turns the vehicle will go into bind and it'll usually break spider gears, which left gone unoticed will wreck the rest of the diff and ring and pin gears.

Get some specific detail of what he is saying and or pics also

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Monday, November 19th, 2018 AT 7:29 PM (Merged)

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