Front differential and drive shaft

JESSICARBY

MEMBER
2004 MERCURY MOUNTAINEER
V8
AWD
AUTOMATIC
220,000 MILES

I started hearing a loud pop noise after being stopped, the pop noise would accurate when I went to go then go away. Did it one time one day then a few days later a few more times to nothing for four days, then one day was driving and it did it like six times. After the third pop sound that day a bad smell arouse and slit what looked to be oil was under vehicle. Kept driving, then smell got worse, and a little smoke and a few more popular sounds. Finally in sixth pop sound car shook and tires would move, lots of smoke and horrible smell. Pulled over immediately.

Had it towed to a mechanic where he told me my front differential needs replaced. So had it replaced, while in repair he said the u joints on the drive shaft are bad so he had to replace that. After a week I get my vehicle back, after driving forty five minutes I get five minutes from my home and same pop sound, smell and fluid appears again. What is going on? This by all means was not a cheap fix and seems like I wasted my money.

5 Replies

HMAC300

MECHANIC
48,601 POSTS

If you are seeing fluid try to see if it is a differential or an axle shaft, it may be the shaft and may have not been installed all the way or the joint is failing/breaking. I would take it back to where it was fixed and have him look it over once more his work should be guaranteed. It may be a broken bracket when axle mounts as well. Also because of this system make sure both front tires are of same size, a 1/2" difference on outside can cause problems for this vehicle.

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Sunday, January 8th, 2017 AT 10:42 AM

JESSICARBY

MEMBER
3 POSTS

I cannot tell where the fluid is from. It is in front and back. Had a friend who is a diesel mechanic work on it. Probably my first mistake there. But fluid looks more on the front and back of shaft.

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Sunday, January 8th, 2017 AT 10:48 AM

HMAC300

MECHANIC
48,601 POSTS

Was this a used unit that was put in like the whole axle assembly? If there is fluid the bearing may be gone on both the differential and tcase I am assuming it is the driveshaft you are talking about and not the axles shafts. Also is there a lot of fluid leaking out like a puddle on both ends or just wet? If it is just wet then it may need a seal in both spots but if a puddle goes out like the diameter of a large can then it is a problem.

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Sunday, January 8th, 2017 AT 11:49 AM

JESSICARBY

MEMBER
3 POSTS

The front differential and drive shaft were both used parts that were put on no puddles on ground but really wet with some dripping.

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Sunday, January 8th, 2017 AT 12:01 PM

HMAC300

MECHANIC
48,601 POSTS

That could be just a seal then try a new one or see if driveshaft has a lot of movement up and down at differential, if it does it may be the bearing. Or the area where the seal rides may have a deep score in it and cannot seal, they may have a ring to put on it with a larger seal to fix it. Make sure when new seal goes in you use oil/grease/Vaseline on seal surface so it is not dry.